LU~
UN
IVERSITY OF
UNIVERSITY
OFWWISCONSIN-EXTENSION
IS CO NS IN -E XT EN
SI ON
GE OL OG
IC AL AN
D NA
GEOLOGICAL
AND
NATURAL
HISTORY
SURVEY
TU RA L HI
ST
OR Y SU RV EY
M er ed ith E. Os
tro m I St
Meredith E. Ostrom,
State
and
Director
at e Geologist
Ge ol og ist an
d Di re ct or
PRECAMBRIAN INLIERS
PRECAMBRIAN
INliERS IN
IN
SOUTH-CENTRAL W
SOUTH—CENTRAL
WISCONSIN
ISCONSIN
Prepared
Pr ep ar ed for:
fo r:
TW EN TY -F OU RT ANNUAL MEETING
TWENTY-FOURTH
H AN NU AL ME ET
IN G
IN ST IT UT E ON
ON LAKE
INSTITUTE
LA KE SUPERIOR
SU PE RI OR GEOLOGY
GE OL OG Y
UN IV ER SI TY OF
UNIVERSITY
OF WISCONSIN-MILWAUKEE
W IS CO NS IN -M IL
W AU KE E
MI LW AU KE E, WISCONSIN
MILWAUKEE,
W iS CO NS IN
M AY9—14,
MAY
1978
9_ 14 ,1
97 8
FI
ELD TR
IP
FIELD
TRIP
GU
ID
E
BO
OK
GUIDE BOOK
NU
M BE R 22
NUMBER
19
78
1978
Field Trip
Trip Guide
Guide Book
Book
Number
Number 22
University of Wisconsin-Extension
Wisconsin—Extension
GEOLOGICAL
GEOLOGICAL AND
AND NATURAL
NATURAL HISTORY
HISTORY SURVEY
SURVEY
Meredith E. Ostrom,
Ostrom, State Geologist
Geologist and
and Director
Director
PRECAMBRIAN
PRECAMBRIAN INLIERS
INLIERS IN
IN SOUTH-CENTRAL
SOUTH-CENTRAL WISCONSIN
WISCONSIN
(companion volume
volume to Geoscience Wisconsin
Wisconsin Volume
Volume 2)
2)
With
With contributions
contributions by
by
Rachel K.
A. Paull,
K. Paull,
Paull, Richard A.
Paull, and Eugene I.
I. Smith
Edited by
by
Eugene I.
I. Smith,
Smith, University of Wisconsin-Parkside
of of
Wisconsin-Milwaukee
A. Paull,
Paull,University
University
Wisconsin-Milwaukee
Richard A.
G. Mudrey,
Mudrey, Jr.,
Jr., Geological and Natural History Survey
M. G.
for
Prepared for
Twenty—Fourth
Twenty-Fourth Annual Meeting
INSTITUTE ON LAKE SUPERIOR
SUPERIOR GEOLOGY
GEOLOGY
University of Wisconsin, Milwaukee
Milwaukee
Milwaukee,
Milwaukee, Wisconsin
May 9—14,
9-14:, 1978
A. Paull,
Paull, Chairman,
Chairman, Field Trip Committee
Richard A.
University of Wisconsin—Milwaukee
Wisconsin-Milwaukee
Available from the Wisconsin Geological and Natural History Survey,
Survey,
of Wisconsin—Extension,
1815 University
University Avenue,
University of
Wisconsin-Extension, 1815
Avenue, Madison,
Madison,
Wisconsin 53706
1978
CONTE
NrS
CONTENTS
Page
Page
INTRODUCTION by Eugene I.
I. Smith
Smith. • • • • • • • • • • • • • • • • • • • • •
11
FRIDAY,
FRIDAY, MAY
MAY 12,
12, 1978
1978
Geologic
Geologic Road
Road Log
Log for
for U.S.
U.S. 41
41 from
from the
the Intersection
Intersection of
of Wisconsin
Wisconsin 74
74
Menomonee
Menomonee Falls
Falls at
at the
the North
North Edge
Edge of
of Waukesha
Waukesha County
County to
to Oshkosh,
Oshkosh,
Wisconsin
Wisconsin (junction
(junction Wisconsin
Wisconsin 21)
21) by
by Richard
Richard A.
A. Paull
Paull and
and Rachel
Rachel
K. Paull
Paull
K •
. .
.
.
.
.
. .
• • • . . • • . .
• .
.
.
.
.
5
.
SATURDAY, MAY 13,
13, 1978
1978
SATURDAY,
to Precambrian Rhyolite and
and
Geologic Road Log for aa Field Excursion to
Granite Inliers
Inliers of South—Central
South-Central Wisconsin by Rachel K.
K. Paull
Paull
A. Paull • • •
• • • • • • • • • •
and Richard A.
11
11
GEOLOGICAL STOP
STOP DESCRIPTIONS by Eugene I.
I. Smith
Stop 11 —- Granite
Granite at Flynn's Quarry
Quarry County Park.
Park • • •
Stop
Stop 2 —- Rhyolite
Rhyolite at Observatory Hill
Stop 33 —- Rhyolite at Marcellon
Marcellon.• • • • •
Stop 4 -- Rhyolite at Marquette • • • • •
.
. •
. •
• •
. ••
Supplemental Stop —- Rhyolite
•
Rhyolite at Ingall's Knob •
Stop 5 —- Quartzite
Portland.
Quartzite at Portland
.
•
.
33
49
49
57
68
76
83
88
REFERENCES
REFERENCESCITED.
CITED. • •• .
.
ILLUSTRATIONS
Figure 1.
1.
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
2.
2.
3.
3.
4.
4.
5.
5.
6.
6.
7.
7.
8.
8.
9.
9.
10.
10.
11.
11.
12.
12.
13.
13.
14.
14.
15.
15.
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
16.
16.
17.
17.
18.
18.
19.
for the Lake Superior Institute field
Route for
field trip to the south—
southcentral Wisconsin Precambrian rhyolite and granite inliers •.
•
Flynn's Quarry County Park • •
compass map of
of Flynn's
Pace and compass
Contact between granite porphyry dike and granite • •
•
Metabasalt dike cutting
cutting granite.
granite. • • • • • • • • •
Route map from Redgranite to
to Montello.
Montello. ~ • •. •. • . . • • .
Elemental concentrations for
for rhyolite
rhyolite groupings
groupings • •
•
Geologic map of Observatory
Observatory Hill
Hill • •. • • • • • • •
•
sandstone outcrops on Observatory Hill.
Cambrian sandstone
Hill. • . . . •
•
in Cambrian
Cambrian sandstone
Conglomerate in
sandstone • • • • • • • • • • . .
.
Contact between rhyolite dike and rhyolite
•
of contact of
Close-up
of rhyolite dike and
and rhyolite.
rhyolite.
Close—up of
•
Route map for
for traverses on the Marcellon exposures • • • • •
Geologic map
map of
of the
the Marcellon
Marcellon inlier
inlier • • • • • • •
Geologic
Photomicrograph of
of Marcellon
Marcellon rhyolite
rhyolite ash-flow
ash—flow tuff
tuff • • • • • • •
Photomicrograph
Stratigraphic variation in
in elemental
elemental concentrations
concentrations for
for
Stratigraphic
the Marcellon
Marcellon rhyolite
rhyolite • • • • • • • • • • • • • • • • • •
the
• •
. •. •• . ..
Weathered spherulites in the Marcellon rhyolite.
rhyolite • •
of spherulitic
spherulitic texture
texture in Marcellon
Marcellon rhyolite
Photomicrograph of
of spheroid
spheroid with
with concentric
concentric bands
bands • • • • •
Photomicrograph of
Photomicrograph of
of spheroid
spheroid with
with aa core
core of
of coarse
coarse quartz
quartz
Photomicrograph
and epidote.
and
•
.
.
.
.
.
.
•
•
.
•
.
.
•
.
•
.
.
.
• . . .
epidote.
•
•.
•
.
•
.
.
•
•
i1
22
32
32
33
35
35
36
37
48
49
49
50
50
53
53
56
56
58
58
59
59
59
59
60
62
62
62
63
63
Page
Figure 20.
20. Pumice
Pumice and
and shard
shard fragments
fragments in Marcellon
Marcellon rhyolite
rhyolite • •
Figure
Figure 21.
21. Lineation formed
formed by
by stretched
stretched pumice
pumice in
in the
the Tertiary A.
A. L.
L.
Figure
Tuff, San
San Mateo
Mateo Mountains,
Mountains, New
New Mexico
Mexico • •
. •
. •
Peak Tuff,
. •••••••
Figure 22.
22. Folds in the Marcellon rhyolite
rhyolite. • • • • • • • • • •
• •••
Figure 23.
23. Sketches
Sketches of
of folds
folds in the
the Marcellon
Marcellon rhyolite
rhyolite• • • • • •
. •
. •. •
Figure
Figure 24.
24. Route
Route map
map for
for traverses
traverses at
at the
the Marquette
Marquette exposures
exposures • •. •. •. •
Figure
Figure 25.
25. Geologic map of the Marquette inlier • • • • • • • •
Figure 26.
26. Rb/Sr-Na
Rb/Sr—Na20/K20
plot for
for Marquette
Marquette rhyolite
rhyolite • • •
.
•
. . •
Figure
0/K 0 plot
2
2
Figure 27.
27. Photomicrograph
Photomicrograph of
of shards
shards in
in Marquette
Marquette rhyolite
rhyolite • •
Figure
.
Figure 28.
28. Photomicrograph of shards in Marquette rhyolite.
rhyolite • • • • • • •
Figure 29.
29. Sketch map of breccia on Ingall's
Ingall's Knob • •
.
. •••
Figure 30.
30. Detailed map of
of the Portland quartzite quarries.
quarries • • . . . . . . .
Figure 31.
31. Photomicrograph of
of the Waterloo Quartzite • • • • •
Figure 32.
32. Detailed route map through the Waterloo Quartzite area
area.
Figure 33.
33. View of phyllite layer in quartzite
quartzite. • • • •
• •••
Close—up of foliated
Figure 34.
34. Close-up
foliated Waterloo Quartzite • • • • • • • •.
.
.
.
.
65
65
66
67
68
6969
70
76
77
79
82
84
85
87
87
TABLES
TABLES
Table 1.
Table
1.
for Central Wisconsin inliers and igneous
Chemical analyses
analyses for
rocks in
in the
the Baraboo area
area. • • • • • • • • • • • • • • • • •
39
INTRODUCT
ION
INTRODUCTION
Eugene I.
Smith1l
Eugene
I. Smith
v
years very little attention has
has been paid to the
For the
the past seventy years
At the
well known
igneous rock in
in the
the Fox
Fox River
River Valley.
Valley. At
the turn of the
the century well
geologists
Chamberlin, Weidman.
Weidman. Leith and
Hobbs described
geologists such as
as Irving,
Irving, Chamberlin,
and Hobbs
these isolated
these
isolated exposures of Precambrian rock.
rock. Between 1907 and 1972 few
The last
geological studies
studies were
were initiated.
initiated. The
last major field
field trip to visit these
was conducted by A.
A. Leith in 1935 for
Precambrian rocks
rocks was
for the
the Kansas
Kansas Geological
While the
will be
be shown to you on this
Society. While
the geology that
that will
this Lake Superior
Institute
field trip is based for
Institute field
for the
the most part
part on
on geological
geological studies
studies comcom1972, descriptions
descriptions of the
Hill rhyolite
pleted since 1972,
the Observatory Hill
rhyolite and
and the
Waterloo
This field trip
Waterloo Quartzite
Quartzite rely
rely considerably
considerably on
on the
the earlier
earlier work.
work.
This
trip
is intended
intended to
to introduce
introduce you
you to
to the
the rock
rock types
types and
and the
the rock
rock fabric
fabric formed
formed
is
post—Penokean igneous
event (1765
m.y. ago)
ago) and
during a
a major post-Penokean
igneous event
(1765 m.y.
and to demonstrate
the structural
structural style of a post—Penokian
The
the
post-Penokian deformation
deformation (1650
(1650 m.y.
m.y. ago?).
ago?).
field trip stops
oldest to youngest
field
stops are
are arranged
arranged in stratigraphic
stratigraphic order from
from oldest
youngest
(fig. 1).
1). Since the
the exposures are
are on
on the
the flank
flank of
of the
the Wisconsin
Wisconsin Arch,
Arch,
(fig.
travelling to the
travelling
the southeast off the
the crest of
of the
the arch
arch conveniently
conveniently exposes
exposes
younger units.
units.
Here fine—grained
The first
first stop is
is at
at the
the Flynn's Granite
Granite Quarry.
Quarry. Here
fine-grained
granophyric granite is
is cut
cut by
by granite
granite porphyry
porphyry and
and metabasalt
metabasalt dikes.
dikes. The
granite probably is the
equivalent of
of the
rhyolites to be
the subvolcanic
subvolcanic equivalent
the rhyolites
3, and
viewed at
at stops
stops 2,
2, 3,
and 4.
4.
Hill (stop
by a
sequence of
of steeply dipping
Observatory Hill
(stop 2)
2) is
is formed
formed by
a sequence
porphyritic rhyolite
which erupted
erupted from
from source
source chambers
chambers now
porphyritic
rhyolite ash—flow
ash-flow tuffs
tuffs which
represented by granite cropping out to
represented
to the
the northwest
northwest (Flynn's
(Flynn's Quarry,
Quarry,
The rhyolite
rhyolite is
cut by
by finefine— and
coarse—grained
Montello and
and Redgranite).
Redgranite). The
is cut
and coarse-grained
rhyolite dikes and
and is
is surrounded
surrounded by
by exposures
exposures of
of Cambrian
Cambrian sandstone.
sandstone.
Stops 33 and
Marcellon and
and Marquette
Marquette rhyolites)
rhyolites) display the
fabric
Stops
and 44 (The
(The Marcellon
the fabric
and
and mineralogy of the
the texturally
texturally variable
variable rhyolites.
rhyolites.
In
In the
the volcanic
volcanic section
sparsely-porphyritic
sparsely—porphyritic plagioclase-bearing
plagioclase—bearing rhyolite
rhyolite commonly alternates
alternates with
with
quartz, plagioclase,
porphyritic quartz,
plagioclase, alkali
alkali feldspar
feldspar rhyolite.
rhyolite. The rocks
rocks show
show
fabrics common
common to ash-flow
ash—flow tuffs
have undergone
undergone compaction,
compaction, welding
welding and
and
fabrics
tuffs that
that have
late—stage primary laminar
flowage (eutaxitic
and spheruloidal
spheruloidal textures
late-stage
laminar flowage
(eutaxitic and
textures and
and
large flow folds).
folds).
The Waterloo Quartzite
Quartzite (stop
5), the
youngest exposed
exposed Precambrian
Precambrian rock
The
(stop 5),
the youngest
in south-central
south—central Wisconsin,
Wisconsin, is
is folded
folded into
into a
broad eastward
eastward plunging synsyn—
a broad
dine. The
The nose
nose of
of the
structure lies
lies in
the Portland
Portland area
area near
near the
quarry
cline.
the structure
in the
the quarry
visited during Stop
stop 5.
5.
1'Division
Division of
of Science,
Science, University
University of
of Wisconsin—Parkside,
Wisconsin-Parkside, Kenosha,
Kenosha, Wisconsin
Wisconsin
53141
53141
1
1
Red granite
Redgranite
S TO p'1)!e!.---.oE::-----I
CD
Flynn's
Quarry
County Park
STOP
Du Lac
@) Marquette
Rhyolife
Rhyolite
Hill
Marcellon
R hy o life
/
z
C,
Waterloo
Quart zite
I
\
'::')"""----~+--~I
Mllwaukee\
o
o
0
10
20
30
30
C-)
w
uJ
~
<t
-J
...J
40 MIles
40
Miles
SCALE
Figure 1.
1.
Route for
the Lake
Lake Superior
Superior Institute
the south—
Route
for the
Institute field
field trip to
to the
southcentral
Wisconsin
Precambrian
rhyolite
and
granite
inliers.
central
rhyolite and granite inliers.
2
I
thank Pattie
Pattie Fields-Troha
Fields—Troha for
for typing
typing draft
draft copies
copies of
I thank
of these
these stop descriptions and Jill Ann Hartnell for
for drafting
drafting the
the figures.
figures.
Diane Pyper made
many useful
editorial corrections
corrections that
that helped
helped smooth
smooth out
out the rough spots.
many
useful editorial
spots.
also thank
thank Frank
Frank Luthur
Luthur (University
(University of
of Wisconsin-Whitewater)
Wisconsin—Whitewater) for
for an
an
II also
informative discussion on
on the
the metamorphic
metamorphic rocks
rocks from
from Waterloo.
Waterloo.
Participants on this trip
will traverse
Participants
trip will
traverse the
the scenic,
scenic, glaciated countryside
side of southeastern and
and south—central
south-central Wisconsin to study isolated exposures
of Precambrian granite,
granite, rhyolite,
quartzite that
rhyolite, and
and quartzite
that project through a cover
of Paleozoic rocks
of
rocks and Pleistocene drift (Fig.
(Fig. 1).
1).
Board bus at 6:30 P.M.
P.M. sharp on Friday May 12,
12, 1978 in
in the front of the
the
Pfister Hotel (Headquarters
(Headquarters for
for the
the 24th
24th Annual
Annual Lake
Lake Superior
Superior Institute).
Institute).
of travel
will follow U.S.
Our route
route of
travel will
U.S. 41
41 to
to Oshkosh,
Oshkosh, Wisconsin.
Wisconsin. A
A geological
roadguide for
for this
this part
part of
of the
the trip
trip is
is provided.
provided. Overnight accommodations
accommodations
will
will be at
at the Pioneer Inn,
Inn, on the west shore of Lake Winnebago in
in Oshkosh
8:00
trip
This
6:30
On Saturday
Saturday May
May 13,
13, 1978,
1978, board
board the
the bus
bus in
front of
of the
the Pioneer
Pioneer at
at
On
in front
A.M.
A.M. sharp.
sharp. The guidebook includes
includes a
a geologic roadguide for the field
field
route,
route, as well as
as detailed information
information on
on each
each of
of the
the geologic
geologic stops.
stops.
field
field excursion will terminate at the Pfister Hotel in
in Milwaukee about
about
P.M.
P.M.
A companion volume to this Geoscience Wisconsin Volume 2,
2, contains papers
papers
by Smith (1978c),
Van Schmus (1978)
(1978c), Van
(1978) and Haimson (1978)
(1978) on the
the geology,
geology, ages,
ages,
and
and engineering properties of
of the
the granites,
granites, rhyolites
rhyolites and
and quartzites.
quartzites.
3
Friday,
Friday, May
May 12,
12, 1978
1978
Geologic
Geologic Road
Road Log
Log for
for U. S.
S. 41
41 from
from the
the Intersection
Intersection of
of Wisconsin
Wisconsin 74
74
Menomonee
Menomonee Falls
Falls at
at the
the North
North Edge
Edge of
of Waukesha
Waukesha County
County
to
to
Oshkosh,
Oshkosh, Wisconsin
Wisconsin (junction
(junction Wisconsin
Wisconsin 21)
21)
1
2
Richard
Richard A.
A. Paull1
Paull and
and Rachel
Rachel K.
K. Paull2
Paull
U.
U. S.
S. 41
41 trends
trends north—northwesterly
north-northwesterly through
through the
the glaciated
glaciated Eastern
Eastern Ridges
Ridges
and Lowlands
Lowlands Province
Province of
of Wisconsin.
Wisconsin. The
The orientation of this
this route
route is
is such
such
and
that
that it
it cuts
cuts obliquely
obliquely across
across the
the strike
strike of
of the
the Paleozoic
Paleozoic formations.
formations. From
From
south—southeast
south-southeast to
to the
the north—northwest,
north-northwest, these
these units
units include
include Silurian
Silurian dolomite,
dolomite,
Tipper
Ordovician Maquoketa
Maquoketa Shale,
Shale, and
and the Middle Ordovician
Upper Ordovician
Ordovician Platteville—
PlattevilleGalena formations.
formations. However,
However, the
the bedrock
bedrock along
along the
the highway
highway is
is largely
largely obobGalena
scured
scured by
by Wisconsinan (Woodfordian
(Woodfordian and
and the
the younger
younger Valderan)
Valderan) glacial
glacial deposits.
deposits.
exception exists
exists along
along the
the crest
crest of
of the
the prominent
prominent Niagaran
Niagaran (Silurian)
(Silurian)
An exception
escarpment, where
where glacial
glacial deposits
deposits are
are thin.
thin.
escarpment,
Included
Woodfordian glacial
glacial features
features are
are well—displayed
well-displayed along
along U.
U. S.
S. 41.
41.
Included
are a
a recessional moraine related to retreat of the Lake Michigan lobe,
lobe, kames
kames
and kettles
kettles associated with the spectacular Kettle Interlobate
Interlobate Moraine,
Moraine, and
and
well—formed
well-formed drumlins
drumlins within the area occupied by the
the Green Bay lobe.
lobe. Deposits
Deposits
that accumulated
accumulated in
in Glacial
Glacial Lake
Lake Oshkosh
Oshkosh when
when retreat
retreat of
of the
that
the last
last Wisconsinan
(Valderan) ice
ice tongue
tongue blocked northeastward drainage
(Valderan)
drainage into
into Green
Green Bay
Bay are
are also
also
traversed.
Details on the
the geology
geology encountered
encountered along
along U.
U. S.
S. 41
are provided
provided in the
Details
41 are
the
geologic road log that
that follows.
follows. We hope this
this will help to make your
your
enjoyable. Mileages in
in the
the road
road log
log are
are cumulative,
cumulative, with
journey more enjoyable.
mileage increments between each
each entry
entry included
included in
in brackets.
brackets.
Mileages
o
0
(2.0)
(2.0)
Con—
74 exit
exit from U.
U. S.
S. 41
Wisconsin 74
41 to
to downtown Menomonee Falls.
Falls.
Continue
northwest on U.
U. S.
S. 41
Oshkosh, the
tinue northwest
41 and
and 45 toward
toward Oshkosh,
the location of
tt
our "watering
our
watering hole"
hole " for
for this
this evening.
evening.
Lime Kiln Village
Village Park is
mile west
west in the
Lime
is about
about one mile
the heart
heart of
Here,
the
the business
business district
district of Menomonee Falls.
the
Falls. Here, the Silurian
Dolomite
dolomite
forms
a
small
falls
on
the
dolomite forms a small falls
the Menomonee River.
River.
was
quarried
here
for
lime
production
as
early
as
the
1850's,
was quarried
for lime
as
as the 1850's, and
Glacial
three historic
historic kilns
three
kilns are preserved within the
the park.
park.
striae on
on the
the Silurian bedrock in
striae
in the
the vicinity
vicinity of
of the
the kilns
kilns
establish an
an east-west
east—west flow
flow direction
direction for
for advance
advance of
of the
the Lake
Lake
establish
Michigan glacial
glacial lobe during the
Michigan
the Woodfordian.
2.0
2.0
(5.0)
(5.0)
Enter Washington
Washington county
county in an
Waukesha/Washington county line.
Waukesha/Washington
line.
Enter
area of
of foIling
folling countryside,
countryside, on
on the
the northwestern
northwestern edge
edge of
of the
the intensely
intensely
area
lThe
1The University
University of
of Wisconsin-Milwaukee,
Wisconsin—Milwaukee, Milwaukee,
Milwaukee, Wisconsin
Wisconsin
University of
of Wisconsin-Madison,
Wisconsin—Madison, Madison,
22The
The University
Madison, Wisconsin;
Wisconsin; and
and Alverno
Alverno College,
College,
Milwaukee,
Milwaukee, Wisconsin
Wisconsin
55
Mileages
Mileages
urbanized, greater
greater Milwaukee
Milwaukee area.
area. This
urbanized,
This region
region was
was last
last glaciated
glaciated
during the
the Woodfordian
Woodfordian by
by the
the advance
advance of
of the
the Lake
during
Michigan
Lake Michigan lobe.
lobe.
The outermost
outermost (oldest)
(oldest) of
of a a series
series of
of three,
three, major
major ridgeridge—
The
forming recessional
recessional moraines
moraines (Lake
Border Moraines),
Moraines), which
forming
(Lake Border
which parallel
parallel
the
shore
of
Lake
Michigan
in
the
Milwaukee
the shore of Lake Michigan in the Milwaukee area,
area, trends
trends through
through
this area.
area.
this
To the
the west,
west, one
one catches
catches glimpses
glimpses of
of the
the irregular
irregular hills
To
hills of
of the
the
Woodfordian
interlobate
moraine
that
developed
Woodfordian interlobate moraine that developed between
between the
the Lake
Lake
Michigan lobe
lobe on
on the
the east
east and
and the
the Green
Green Bay
Michigan
Bay lobe
lobe on the west. This
This
is
the
Kettle
Interlobate
Moraine,
which trends
is the Kettle Interlobate Moraine, which
trends north-northeast
from Walworth
Walworth County
County to
to Kewaunee
Kewaunee County
County to
from
to form
form the
the glacial
glacial backbone
of
eastern
Wisconsin.
bone of eastern Wisconsin. Northwest-trending
Northwest—trending u.s.
U.s. 41
41 is
is on
on aa
collision course
course with
with this
this prominent
prominent topographic
topographic feature.
collision
feature.
7.0
7.0
(1.0)
(1.
0)
8.0
8.0
Wisconsin 167
167 (Holy
Hill Road)
Road) exit;
exit; continue
continue on
Wisconsin
(Holy Hill
and 45.
45.
on u.s.
U.S. 41
41 and
Holy
Hill,
aprominentkame
topped
by
Holy Hill, a prominent kame
by aa picturesque
picturesque church,
church, is
located about
about 77 miles
miles west
west of
of here
here within
within the
the heart of the Kettle
located
Interlobate Moraine.
U.S.
u.s.
45 exit
exit to
to West
West Bend;
Bend; continue
continue north
north on U.S.
45
u.s. 41.
41.
(4.0)
(4.0)
12.0
12.0
(1.0)
(1.
0)
13.0
13.0
(lO)
(1. 0)
14.0
14.0
(0.4)
(0.4)
14.4
14.4
(0.9)
(0.9)
The highway
highway ascends
ascends the
the eastern
eastern edge
edge of the
the Kettle
The
Kettle Interlobate
Moraine,
and
leaves
the
lowland
occupied
by the Lake Michigan lobe
Moraine,
during the Woodfordian advance.
advance. This
This country is
is higher and more
more
irregular,with
with kettles
kettles and
and abundant
abundant locally
locally derived
derived erratics
irregular,
of
erratics of
light—colored Silurian
light-colored
Silurian dolomite.
dolomite.
Wisconsin 60 exit to Slinger and Hartford within the Kettle Inter—
Interlobate Moraine.
Moraine ..
The Hilltop Restaurant on the west side of the highway is
is well
well
named,
named, for
for it
it occupies
occupies the
the crest
crest of
of the
the Kettle
Kettle Interlobate
Interlobate Moraine.
Moraine.
The
The scenic
scenic kettle
kettle and
and kame
kame topography
topography that
that characterizes
characterizes this
this region
region
formed
formed when the Green Bay and Lake Michigan glacial lobes
lobes stagnated
stagnated
along
along their
their junction
junction during
during the
the Woodfordian.
Woodfordian. As
As the
the ice
ice at
at the
the
melting edges
edges of
of these
these juxtaposed
juxtaposed lobes
lobes began
began to
to thin,
thin, sedimentsedimentladen meltwater
meltwater •flowed
flowed down
in the
the ice
ice to
to provide
provide
laden
down cracks
cracks and holes in
aa source
source for
for subglacial
subglacial streams.
streams. Meltwater
Meltwater also
also cascaded
cascaded over
over the
the
ice
ice surface
surface into
into the
the widening abyss
abyss between the
the tongues.
tongues. Here,
Here,
large
large chunks
chunks of
of ice
ice were buried in
in the
the outwash
outwash sands
sands and
and gravels.
gravels.
The
The resulting
resulting maze
maze of
of crevasse
crevasse fills,
fills, moulin
moulin kames,
kames, eskers,
eskers, outwash
outwash
fans,
fans, and
and kettles
kettles is
is superimposed
superimposed on
on aa dual
dual complex
complex of
of ridges
ridges which
which had
had
previously
previously formed
formed as
as lateral
lateral moraines.
moraines.
Little Switzerland
Switzerland Ski
Ski Hill,
Hill, to
to the
the west
west of
of the
the highway
highway at
at the
the edge
edge
Little
of
of Slinger,
Slinger, utilizes
utilizes aa prominent
prominent moulin
moulin kame.
kame. The
The internal
internal makeup
makeup
of
of aa similar
similar kame
kame is
is revealed
revealed in
in an
an abandoned
abandoned sand
sand and
and gravel
gravel
operation
operation about
about 0.1
0.1 mile
mile north
north of
of the
the ski
ski hill.
hill. The
The gravel
gravel in
in this
this
kame
kame is
is well—stratified,
well-stratified, and
and it
it includes
includes an
an abundance
abundance of
of lightlightcolored Silurian
Silurian dolomite
dolomite cobbles
cobbles and
and aa few
few large
large boulders.
boulders. Other
Other
colored
well-formed
well-formed kames
kames are
are present
present east
east of
of the
the highway.
highway.
66
Mileages
Mileages
15.3
15.3
Junction
Junction U.S.
u.s. 41
41 and
and Wisconsin
Wisconsin 144.
144.
Continue
Continue north
north on
on U.S.
u.s. 41.
41.
(1.7)
(1.7)
17.0
17.0
(0.8)
(0.8)
17.8
17.8
(3.5)
(3.5)
Junction
Junction U.S.
u.s. 41
41 and
and County
County K.
K. The
The highway
highway descends
descends from
from the
the
Interlobate
Interlobate Moraine toward
toward the
the lowland
lowland area
area occupied
occupied by
by the
the Green
Green
Bay lobe
lobe during
during the
the Woodfordian
Woodfordian ice
ice advance.
advance.
Bay
The sand
sand and
and gravel
gravel pit
pit west of
of the
the highway
highway is
is on
on the
the northnorthwestern
western edge
edge of
of the
the Kettle
Kettle Interlobate
Interlobate Moraine.
Moraine. This
This is
is one
one of
of
many
many such
such operations
operations that
that exploit
exploit the
the abundant
abundant resource
resource of
of waterwaterwashed
washed sand
sand and
and gravel
gravel within
within this
this unique
unique morainal
morainal complex.
complex.
The route
poorly—drained ground
route ahead
ahead traverses
traverses gently
gently rolling,,
rolling, poorly-drained
moraine. Tamaracks
Tamaracks flourish
flourish in
in some
some of
of the
the wetter
wetter areas.
areas.
moraine.
21.3
21.3
(1.7)
(1.7)
23.0
23.0
Junction
Junction U.S.
u.s. 41
41 and
and Wisconsin 33;
33; continue
continue north
north on
on U.S.
u.s. 41.
41. The
The
route
route crosses
crosses aa recessional
recessional moraine that
that formed
formed as
as the
the Woodfordian
Woodfordian
Green Bay
Bay lobe
lobe paused
paused during
during its
its retreat.
retreat.
Green
Wayside east
east of
of the
the highway is
is in
in an
an area
area of
of swampy,
swampy, rolling
rolling ground
ground
(4.0)
(4.0)
moraine.
moraine.
27.0
27.0
(2.5)
(2.5)
This high area provides an excellent overview of scenic,
scenic, irregular
irregular
abundance of
of erratics
erratics in
in the
the till
till here
here is
is documented
documented
countryside. An abundance
by
by stone
stone fences
fences that
that line
line some
some fields,
fields, and
and by
by rock
rock piles
piles in
in others.
others.
29.5
(0.6)
(0.6)
u.s. 41
41 and
and Wisconsin
Wisconsin 28.
28.
Junction U.S.
30.1
(1.9)
(1.9)
county line.
line. Enter Dodge County in
in an
an area
area dominated
dominated
Dodge/Washington county
large, well—formed
well-formed druinlins.
drumlins. Erratics in
in fence
fence rows
rows and
and farmyards
farmyards
by large,
the stony
stony nature
nature of
of this
this till.
till.
testify to the
32.0
(0.4)
(0.4)
Wayside east of
of the
the highway.
highway.
32.4
(1.6)
(1.6)
Wayside west of
of the
the highway.
highway.
34.0
34.0
(2.4)
(2.4)
The
Junction
67.
Continue north on U.S.
u.s. 41.
41.
The
Junction u.s.
U.S. 41 and Wisconsin 67.
route ahead
ahead gradually
gradually climbs
climbs the
the gentle
gentle (2°-5°),
route
(2°-5°), easterly dipslope
However, the
the bedrock in this
of
resistant Silurian
Silurian dolomite.
dolomite.
However,
of the
theresistant
region is
is covered
covered by
by aa swarm of broad,
broad, low drumlins
drumlins that create
region
aa gently
gently rolling landscape.
36.4
36.4
(1.0)
(1.0)
Junction
49.
Junction u.s.
U.S. 41
41 and
and Wisconsin 49.
37.4
37.4
(1.4)
(1.4)
Fond
line.
Fond du
du Lac/Dodge
Lac/Dodge county line.
38.8
38.8
(0.5)
(0.5)
highway utilize
utilize a
Sand and
and gravel
gravel operations
operations on
on both
both sides
sides of
of the
the highway
Sand
a
local
local area
area of outwash deposits.
39.3
39.3
(2.7)
(2.7)
Roadcut on
on the
the west
west side
side of
of the
the highway
highway exposes
exposes Silurian
Silurian dolomite
dolomite
Roadcut
The proximity
proximity of
of bedrock
bedrock to
to the
the
where
thin.
The
where glacial
glacial deposits
deposits are thin.
77
Continue north
north on
on U.S.
u.s. 41.
41.
Continue north
north on
on U.S.
Continue
u.s. 41.
41.
Enter Fond du
du Lac County.
Enter
County.
Mileages
Mileages
surface has
has facilitated
facilitated the
the development
development of
of numerous
numerous dolomite quarries
surface
in this
this general area.
This rock
rock is
is an excellent dimension
in
area.
This
dimension stone,
stone,
but most
most of it
it is
is crushed for
but
for agricultural lime and road building.
building.
However, some
some is
is kilned to produce chemical
However,
chemical lime.
lime.
This high
high point
point provides
provides aa good
good view
view of
of the
the north-northeasterly
This
trending Kettle
Kettle Interlobate
Interlobate Moraine
Moraine along
along the
the skyline
skyline to
to the
the east.
east.
trending
A lowland region,
nonresistant Middle
Middle
region, developed on relatively nonresistant
and Upper
Upper Ordovician rocks,
and
rocks, lies
lies to
to the
the west.
west.
42.0
42.0
(0.6)
42.6
42.6
(2.0)
Large
Large quarries
quarries in
in Silurian dolomite are located east and west of
U.s. 41.
U.S.
41.
This is
is the
the edge of the
the Silurian (Niagaran)
This
(Niagaran) escarpment,
escarpment, and it
provides
a
fine
view
of
the
Ordovician
lowland
ahead.
provides a fine
the
ahead.
This excarpment (or
ment
(or cuesta)
cuesta) is the
the most significant bedrock feature in eastern
Wisconsin. It
It emerges
emerges from
from aa thick
thick cover
cover of
of glacial
glacial deposits
deposits aa
few miles
miles northeast
northeast of
of Milwaukee,
Milwaukee, and
and trends
trends north-northeast
north—northeast as
few
as aa
prominent cliff along the
the east side of Horicon Marsh and Lake
Winnebago.
From here,
here, the
the escarpment persists northeastward to
form the
the rocky
rocky spine of the Door Peninsula. It continues across
form
Lake Michigan as
as a
Lake
a string of bedrock islands before it rises
rises as the
the
rugged Garden Peninsula of
of Upper
Upper Michigan.
Michigan.
The route
descends toward the Ordovician lowland through
route ahead descends
through an
an
area of gently rolling
ground
moraine.
rolling ground moraine.
44.6
44.6
(0.6)
The highway in this vicinity crosses the ill—defined
The
ill-defined terminal
terminal moraine
of the latest Wisconsinan (Valderan)
(Valderan) ice advance of the
the Green Bay
Bay
lobe.
The wooded edge of the Silurian escarpment is
is visible
visible along
along the
the skyskyline to
to the
the east.
east.
45.2
(1.8)
Junction U.S.
U.S. 41 and Wisconsin 175 to Fond du Lac,
Lac, at
at the
the south
south end
end
of Lake Winnebago.
Winnebago. Continue northwest
northwest on
on U.S.
U.S. 41.
41.
Lake Winnebago,
Winnebago, with a surface area of 215
215 square
square miles and
and aa
maximum
maximum depth
depth of
of 21
21 feet,
feet, is
is the
the largest
largest inland
inland lake
lake in
in Wisconsin.
Wisconsin.
It sprawls for
for 28
28 miles along the west edge of the
the Silurian
Silurian
escarpment,
escarpment, and is situated in an area underlain by relatively
relatively
nonresistant Middle
Middle and
and Upper
Upper Ordovician
Ordovician rocks.
rocks. This lowland
lowland extends
extends
from
from Green Bay southwestward through
through Lake Winnebago, Horicon
Horicon Marsh,
Marsh,
and over a
a low
low drainage divide into
into the
the broad valley
valley now
now occupied
occupied
by
by the
the Rock
Rock River.
River. During the
the Pleistocene, the
the Green
Green Bay
Bay lobe
lobe
advanced and
and retreated
retreated along
along this
this route
route numerous
numerous times.
times. The ice,
ice,
in part confined by the
the resistant
resistant Silurian
Silurian escarpment,
escarpment, scoured
scoured the
the
Ordovician bedrock and deposited aa variety
variety of
of glacial
glacial landforms.
landforms.
During northeastward regressions
regressions of
of the
the Woodfordian
Woodfordian and
and Valderan
Valderan glaciers,
glaciers,
drainage along
along the
the lowland
lowland into
into Green
Green Bay
Bay was temporarily
temporarily blocked
blocked
by
by the
the retreating
retreating wall
wall of
of ice.
ice. A
A vast
vast lake,
lake, termed
termed Glacial
Glacial Lake
Lake
Oshkosh, formed
impounded behind
behind the
the youngest
youngest
formed from
from the
the meltwaters
meltwatersimpounded
(Valderan)
(Valderan) of
of these
these icy
icy dams.
dams. At
At this
this time,
time, the
the site
site of
of Fond
Fond du
du Lac
Lac
was
was under
under 40
40 to
to 60
60 feet
feet of
of water.
water. Eventually
Eventually Green
Green Bay
Bay became
became ice
ice
free,
free, and Glacial Lake Oshkosh drained into Lake Michigan via
via the
the
88
Mileages
Mileages
Winnebago
remnantofofthis
this feature,
feature, surviving
Fox River.
River. Lake
Lake Winnebago
is isa aremnant
surviving
Fox
in a shallow irregularity on the floor
floor of
of this
this ancient
ancient water
water body.
body.
in a shallow irregularity on the
Cross
Cross east
east branch
branch of
of Fond
Fond du
du Lac
Lac River.
River.
47.0
47.0
(1.8)
(1.8)
48.8
48.8
(4.2)
(4.2)
Junction
Junction U.S.
U.S. 41
41 and
and U_S.
U.S. 151.
151. Continue
Continue north
north on
on U.S.
U.S. 41.
41. The
The
route
route ahead
ahead traverses
traverses aa relatively
relatively subdued
subdued area
area underlain
underlain by
by
sediments
sediments deposited
deposited in
in Glacial
Glacial Lake
Lake Oshkosh.
Oshkosh.
Junction U.S.
U.S. 41
41 and
and Wisconsin
Wisconsin 23.
23.
Junction
Continue
Continue northwest
northwest on
on U.S.
U.S. 41.
41.
The
The wooded
wooded Silurian
Silurian escarpment
escarpment continues
continues to
to dominate
dominate the
the horizon
horizon to
to
the east.
east.
the
53.0
53.0
Wayside
Wayside west
west of
of the
the highway,
highway, as
as U.S.
U.S. 41
41 curves
curves northward.
northward.
(4.0)
(4.0)
57.0
(1.7)
(1.7)
58.7
58.7
(3.2)
(3.2)
ascends to
to reddish,
reddish, rolling
rolling Valderan
Valderan ground
ground moraine
moraine at
at
Highway ascends
the western
western edge
edge of
of Glacial
Glacial Lake
Lake Oshkosh.
Oshkosh.
the
Winnebago County
Fond du
du Lac/Winnebago
Lac/Winnebago county
county line.
line. Enter
Enter Winnebago
County in
in an
an area
area
Fond
rolling ground
ground moraine.
moraine. There is a good view to
to the
the east
east of
of the
the
of rolling
Silurian escarpment
escarpment along
along the
the far
far shore
shore of
of Lake
Lake Winnebago.
Winnebago. The
The
sediments deposited
deposited
route from here to Oshkosh traverses reddish sediments
Lake Oshkosh.
Oshkosh.
in Glacial Lake
61.9
61.9
(0.7)
(0.7)
of the
the highway.
highway.
Wayside east of
62.6
62.6
(2.7)
(2.7)
U.S. 41
Junction U.S.
U.S. 41 and Wisconsin
Wisconsin 26.
26. Continue north on U.S.
through aa subdued
subdued area underlain by flat-lying glacial lake
through
deposits.
65.3
65.3
(2.9)
(2.9)
Continue north
north
Junction U.S.
U.S. 41 and Wisconsin 26
26 and
and 44
44 to
to Oshkosh.
Oshkosh. Continue
Oshkosh, on
on the west shore
Winnebago, is
on U.S.
U.S. 41.
41. Oshkosh,
shore of Lake Winnebago,
developed on the ancient floor
floor of
of Glacial
Glacial Lake
Lake Oshkosh.
Oshkosh.
68.2
68.2
The geologic
geologic roadguide
roadguide for
Junction U.S.
U.S. 41 and Wisconsin 21.
21. The
for
intersection,
the Precambrian
Precambrian inliers
inliers field
field trip
trip begins
begins at
at this
this intersection,
the
and
21.
and continues
continues westward on State 21.
A PLEASANT
PLEASANT EVENING:
EVENING
HAVE A
END
- HAVE
END OF
OF LOG -
99
__________
__________
Saturday,
Saturday, May
May 13,
13, 1978
1978
Geologic
Geologic Road
Road Log
Log for
for aa Field
Field Excursion
Excursion to
to Precambrian
Precambrian Rhyolite
Rhyolite and
and Granite
Granite
Inliers
Inliers of
of South—Central
South-Central Wisconsin
Wisconsin
l
2
Rachel
Rachel K.
K. Paull'
Paull and
and Richard
Richard A.
A. Paull2
Paul1
This
This road
road log
log starts
starts at
at the
the intersection
intersection of U.
U. S.
S. 41
41 and
and Wisconsin 21
21 on
on
the
the northwestern
northwestern edge
edge of
of Oshkosh,
Oshkosh, Wisconsin,
Wisconsin, and
and terminates
terminates in
in Milwaukee,
Milwaukee,
'Wisconsin
"Wisconsin at
at the
the junction
junction of 1—94
1-94 with 1—43
1-43 (U.
(U. S. 141) and
and 1—794
1-794 (see
(see
Fig. i).
1).
Fig.
The
The route
route of travel
travel on this
this trip
trip is
is due
due west from
from Oshkosh for
for 26
26 miles
miles
to Redgranite,
Redgranite, and then
then south—southwest
south-southwest nearly
nearly to
to Portage
Portage (Marcellon
(Marcellon inlier).
inlier).
to
Since
Since we detour to
to look
look at
at two
two Precambrian
Precambrian inliers,
inliers, this
this leg
leg involves
involves about
about 50
50
we proceed northeast
miles of
of travel.
travel. From here,
here, we
northeast to
to a
a rhyolite inlier near
miles
Marquette; aa distance
distance of
of 20
20 miles
miles by
by road.
road. After
After aa 5 mile segment
segment to
to the
the east,
east,
Marquette;
our route
route trends
trends south
south for
for 40
40 miles.
miles. From immediately
immediately north
north of
of Waterloo,
Waterloo,
our
we travel
travel eastward
eastward for
for 7
7 miles
miles to
to the
the Waterloo
Waterloo Quartzite,
Quartzite, and
and then
then south
south for
for
we
to reach
reach Interstate
Interstate 94
94 at
at Lake
Lake Mills.
Mills. After aa fast
fast 50—mile
50-mile run
run to
to
8 miles to
In all,
all, we
we will
will cover 206
east, we are
are back
back in
in Milwaukee.
Milwaukee.
206 miles,
miles, make
make
the east,
5 geologic
stops, and even stop
stop for
for lunch
lunch (Fig.
(Fig. 1).
1). It will be
be aa busy
busy day
day:
5
geologic stops,
This odyssey through east—central
east-central Wisconsin traverses
traverses parts of two
two of
However,
the four
four major physical provinces
provinces recognized
recognized in
in Wisconsin.
Wisconsin.
However, in
in the
the
the
provinces are
area
the features
are
area covered
covered by
by this
this field
field excursion,
excursion, the
features of
of both
both provinces
The Eastern Ridges and
by young
young glacial
glacial deposits.
deposits. The
and Lowlands
Lowlands parallels
parallels
masked by
This province
province contains
contains aa sequence
sequence of
of generally
generally north—south
north-south
Lake Michigan. This
striking, Ordovician
Ordovician through
through Devonian formations,
formations, with
with the
older rocks
striking,
the older
rocks to
to the
the
Differences in
in resistance
resistance of
of these
units result
west. Differences
these units
result in broad,
broad, subdued
subdued
ridges alternating with lower
lower areas.
areas.
The Central Plain is
is aa lowland
lowland region,
region,
ridges
developed on Upper
Upper Cambrian sandstones,
sandstones, that
west of
of the
developed
that lies
lies to
to the
the west
the Eastern
Ridges and Lowlands.
Lowlands~
Ridges
Within the
the general region of the
the Central
Central Plain covered by this
this trip,
trip,
there are
are ten localities
localities where
where Precambrian granite
granite and
and rhyolite
there
rhyolite project
project
through
through aa cover
cover of
of Lower
Lower Paleozoic
Paleozoic rocks
rocks and
and unconsolidated
unconsolidated Pleistocene
Pleistocene
The igneous
igneous rocks
rocks in these inliers
deposits.
The
inliers are dated
dated at
at 1765
1765 m.y.
m.y. old,
old,
and they
they probably
probably formed
and
formed during the waning stages
stages of
of the
the Penokean
Penokean orogeny.
orogeny.
Although
Granite inliers
inliers lie
lie northwest
Granite
northwest of the
the area
area where rhyolite
rhyolite is
is exposed.
exposed. Although
the field
field relations
relations are
are not
not established
established at
at present,
present, the
the rhyolite
rhyolite and
and granite
granite
the
If so,
so, the
the granite
granite is
are
comagmatic. If
is a
a subvolcanic
are generally
generally believed
believed to be comagmatic.
equivalent
of
the
extrusive
rhyolite.
equivalent of the
rhyolite.
After accumulation of
of the
sequence of
of Precambrian quartz
After
the rhyolite,
rhyolite, a
a thick sequence
After
deposition, these
sandstone
deposited. After deposition,
sandstone and
and other
other sedimentary rocks was deposited.
rocks and
and the
the underlying
underlying rhyolite
rhyolite were
were subjected
subjected to
to an
an intensive
intensive episode
episode of
of
rocks
Detailed information
information on
on the
the Precambrian
Precambrian
folding,
m.y. ago.
ago.
Detailed
folding, possibly
possibly 1650 m.y.
history of
of this
this region
region is
is provided
provided by
by Eugene
Eugene I.
I. Smith
Smith in
in the
the next
next section
section of
of
history
this
this guidebook.
guidebook.
The five
five stops
stops on
on this
this field
field excursion
excursion provide
provide an
an opportunity
opportunity to
to examine
examine
The
However, rhyolite
rhyolite
each
types described above.
above.
However,
each of
of the
the major
major Precambrian rock types
receives the
the most
most emphasis,
emphasis, with
with three
three stops
stops devoted
devoted to
to an
an examination
examination of
of this
this
receives
diverse
diverse rock
rock type.
type.
11
11
1
1University
of Wisconsin—Madison,
Madison, Madison,
Wisconsin; and
Alverno College,
University
of Wisconsin-Madison,
Wisconsin;
and Alverno College,
Milwaukee,
Wisconsin
Milwaukee, Wisconsin
2University of
of Wisconsin-Milwaukee,
Wisconsin—Milwaukee, Milwaukee,
Milwaukee, Wisconsin
Wisconsin
2University
The glacial
glacial geology
geology of
of east-central
east—central Wisconsin
Wiscctisin is
is also
also spectacular,
spectacular, and
and
The
quite
varied.
The trip
trip begins
begins in
in an
an area
area occupied
occupied by
by the
the youngest
youngest Wisconsinan
Wisconsinan
quite varied.
The
(Vanderan) ice
ice advance,
advance, and
and by
by lakes
lakes which
which formed
formed during
during the
the retreat
retreat of
of this
this
(Vanderan)
ice. However,
However, most
most of
of the
the route
route traversed
traversed is
within the
ice.
is within
the region covered by
an older
older Wisconsinan
Wisconsinan (Woodfordian)
an
(Woodfordian) advance of
of the
the Green
Green Bay
Bay lobe.
lobe. Deposits
Deposits
formed by
by this
this icy
icy tongue
tongue include large expanses of
formed
of glacial
glacial lake
lake sediments,
sediments,
recessional moraines
moraines related
related to
to the
the retreat
retreat of
of this
this lobe,
lobe, outwash
outwash sands
sands and
and
recessional
gravels, scenic
scenic kettle
kettle lakes,
lakes, and
and some
some of
of the
the best
best drumlin
drumlin swarms
swarms in
in the
the
gravels,
world. All
All of
of these
these features
features combine
combine to make
make this
this region
region a
glacial showworld.
a glacial
case, and a
most pleasant
place to
case,
a most
pleasant,place
to spend
spend aa field
field day.
day.
We hope
hope the
the geologic
geologic roadguide
roadguide that
that follows
follows makes
makes your trip more
We
enjoyable. Mileages
Mileages are
are cumulative,
cumulative, with
with mileage
mileage increments
enjoyable.
increments between each
entry provided in
in brackets.
brackets. Detailed
for each stop is
Detailed geologic
geologic information for
provided by Eugene I.
provided
I. Smith in
in the
the next
next section
section of
of this
this guidebook.
guidebook.
It
It would
would
be beneficial
beneficial if
if you
you would
would read
read the
the detailed
detailed descriptions
descriptions of
be
of each area
area before
we stop.
we
stop.
Mileages
Mileages
o0
(2.2)
(2.2)
Start of
of Geologic
Geologic Road
Road Log
Log at
at intersection
intersection of
of V.. S. 41
Start
41 and
Wisconsin 21 at the
the northwestern edge of
of Oshkosh,
Oshkosh, Wisconsin.
Wisconsin.
west on State Highway
Proceed west
Highway 21.
21.
is located
located on
on the
west shore
shore of
of Lake
Lake Winnebago,
Winnebago, the largest
Oshkosh is
the west
inland lake in
in Wisconsin. This shallow lake
lake is
is aa remnant
remnant of
of Glacial
Glacial Lake
Lake
Oshkosh,
Oshkosh, a much larger
larger Pleistocene water body formed
formed when the
the retreating
retreating
Valderan ice
blocked northeastward
northeastward drainage
drainage along
Valderan
ice blocked
along the
the Green Bay lowland
into
into Lake
Lake Michigan.
Michigan. The route ahead traverses lacustrine
lacustrine sediments that
that
accumulated in
in Glacial
Glacial Lake
Lake Oshkosh.
Oshkosh.
2.2
2.2
(2.6)
Enter an
an area
area of
of higher,
higher, gently
gently rolling
rolling countryside.
countryside. This
is
ground moraine
moraine and
is a
a Valderan ground
and outwash complex that
that
once stood
stood as
as an
an island
island in
in Glacial
Glacial Lake
Lake Oshkosh.
Oshkosh.
4.8
4.8
(2.2)
(2.2)
the flat floor of
of
Descend from the morainal "island" onto the
Glacial
Glacial Lake
Lake Oshkosh.
Oshkosh. Here,
Here, the
the lake
lake sediments
sediments are
are
well-drained to
to be
be intensively
intensively farmed.
farmed.
sufficiently well—drained
7.0
7.0
(0.7)
(0.7)
This
This subdued
subdued ridge
ridge is
is the
the western
western edge
edge of
of the
the gentle,
gentle,
east—dipping,
east-dipping, Middle Ordovician
Ordovician (Platteville—Galena
(Platteville-Galena
formations)
formations) cuesta.
cuesta. The route
route ahead
ahead descends
descends through
through the
the
Ordovician St.
St. Peter
Peter Sandstone
Sandstone onto
onto aa relatively
relatively
Middle Ordovician
flat surface
surface developed
developed on
on dolomites
dolomites of
of the
the Lower
Lower Ordovician
Ordovician
flat
Prairie
Prairie du
du Chien
Chien Group.
Group. However,
However, the
the bedrock
bedrock in
in this
this area
area
is
is obscured
obscured by
by glacial
glacial deposits.
deposits.
7.7
(0.3)
Enter
Enter Omro
Omro on
on the
the Fox
Fox River.
River. The
The Fox
Fox flows
flows northeasterly
northeasterly to
to
join the
the southeasterly
southeasterly flowing
flowing Wolf River
River drainage
drainage in
in Lake
Lake
join
Butte
Butte des
des Morts.
Morts. This
This shallow
shallow lake
lake is
is another
another remnant
remnant of
of
Glacial
Glacial Lake
Lake Oshkosh,
Oshkosh, and
and it
it drains
drains into
into Lake
Lake Winnebago
Winnebago at
at
Oshkosh.
Oshkosh.
12
12
Mileages
Mileages
The
The Middle
Middle Ordovician
Ordovician St.
St. Peter
Peter Sandstone
Sandstone is
is quarried
quarried for
for foundry
foundry
This
sand
sand
a
few
miles
south
of
here
near
Waukau.
sand a few miles south of here near Waukau.
This sand is
is trucked
trucked
to
to Berlin
Berlin for
for processing,
processing, but
but from
from 1870-1878,
1870-1878, the
the St.
St. Peter
Peter in
in this
this
area supplied aa glass
factory
in
Omro.
glass factory in Ornro.
8.0
8.0
(0.5)
(0.5)
The
The park
park on
on the
the south
south bank
bank of
of the
the Fox
Fox River
River represents
represents
Unfortunately,
use
use of
of the
the flood
flood plain.
plain. Unfortunately, such
such foresight
foresight
exercised
exercised when
when downtown
downtown Omro
Omro was
was developed.
developed.
intelligent
intelligent
was
was not
not
8.5
8.5
(2.5)
(2.5)
Junction
Junction Wisconsin 21
21 and
and 116
116 at
at the
the west
west edge
edge of
of Omro.
Ornro. Continue
Continue
on
on State
State 21,
21, and
and cross
cross the
the Fox
Fox River.
River. The route ahead
ahead parallels
the north side of the swampy Fox River valley for
for the
the next
next few
few miles.
miles.
11.0
11.0
(2.8)
(2.8)
Another
Another area
area of
of rolling
rolling Valderan
Valderan moraine
moraine that
that once
once stood
stood as
as an
an island
island
in Glacial
Glacial Lake
Lake Oshkosh.
Oshkosh.
13.8
13.8
(2.0)
(2.0)
Intersection Wisconsin
Wisconsin 21
21 and
and County
County K.
K. The gentle
gentle ridge
ridge just
just east
east
of this intersection is the easterly—dipping,
western
edge
of
the
easterly-dipping,
edge of the
Lower Ordovician
Ordovician Prairie
Prairie du
du Chien
Chien escarpment.
escarpment. As such,
such, it
it serves
serves
to define the boundary between the Eastern Ridges
Ridges and
and Lowlands
Lowlands and
and
Central Plain.
Plain.
the Central
The bedrock underlying the
the Central Plain is
is predominantly
predominantly sandstone
sandstone
Late Cambrian
Cambrian age.
age. However, the
the bedrock in
in this
this vicinity
vicinity is
is
of Late
covered by glacial lake
lake sediments.
sediments.
A
A quarry developed
developed in
in the
the Prairie
Prairie du
du Chien
Chien dolomite
dolomite is
is immediately
immediately
intersection. The glacial deposits here are
are thin
thin
southeast of this intersection.
edge of
of the
the cuesta.
cuesta.
along the edge
15.8
15.8
Waushara/Winnebago
WausharajWinnebago county
county line.
line.
Enter Waushara
Waushara County.
County.
(1.3)
(1.3)
17.1
(2.0)
(2.0)
19.1
(1.8)
(1.8)
bogs, like the one north of the highway,
Tamarack bogs,
highway, are common
common in
in poorly—
poorlydrained localities throughout
throughout this
this region.
region.
The truck-farming area south of the road was a former
The
former tamarack
tamarack bog.
When drained by ditching,
ditching, the peaty bog soils are highly productive.
A remnant of the former habitat still exists along the west edge
edge of
of
the tilled
tilled land.
land.
The prominent line of northeasterly trending ridges about
about 33 miles
here is
northwest of here
is part
part of
of the
the Woodfordian
Woodfordian morainal
morainal complex.
complex.
These ridges,
ridges, which
which mark
mark the
the western
western edge
edge of Glacial Lake Oshkosh,
These
Oshkosh,
are older
older than
than the
the patches
patches of Valderan
Valderan till previously traversed.
are
traversed.
Continue west
west on
on 21.
21.
20.9
(0.3)
(0.3)
Junction of Wisconsin 21
21 with 49.
49.
21.2
21.2
(5.2)
(5.2)
Good view
view to
to the
the northwest of the hilly Woodfordian
Good
Woodfordian drift.
drift.
The
soils adjacent
adjacent to the road are lacustrine sediments
pinkish to red soils
Poor drainage
drainage and
that accumulated in Glacial Lake Oshkosh.
that
Oshkosh. Poor
numerous tamarack
tamarack swamps
swamps are
are characteristic
characteristic of
of this
this lowland area.
numerous
area.
13
13
Mileages
Mileages
26.4
26.4
(1.3)
(1.
3)
Enter Redgranite
Redgranite and
and Junction
Junction with
with County N.
N.
Enter
County NN toward
toward Lohrville.
Lohrville.
County
Proceed
Proceed west
west on
on
Redgranite was
was once
once the
the site
site of
of aa thriving
thriving quarry
quarry operation
operation and
and
Redgranite
pickle factory.
factory. The
aa pickle
The pickle
pickle factory
factory might
might prosper
prosper again,
again, but
but
the quarry
quarry is
is permanently
permanently abandoned.
abandoned. Now
the
Now flooded,
flooded, it
it is
is the
the focus
focus
of aa city
city park.
park.
of
This
This quarry,
quarry, adjacent
adjacent to
to Wisconsin
Wisconsin 21
21 aa few
few blocks
blocks northwest
northwest of
of
here, employed
employed about
about 260
260 workers
workers in
in 1909
1909 to
to produce
produce hand-trimmed
here,
granite paving
paving blocks
blocks for
for aa few cents apiece.
granite
apiece. With
With the
the average
average
trimmer producing
producing up
up to
to 300
300 blocks
blocks per
per day,
day, four
four trains
trains were
trimmer
were
required
required to
to haul
haul the
the daily
daily output
output southward
southward to
to the
the booming
booming towns
towns of
of
Milwaukee, Chicago,
Chicago, and St.
Milwaukee,
St. Louis. Quarrying
Quarrying declined
declined rapidly
rapidly
after 1915,
1915, when
when concrete
concrete became
became the
the preferred road building
after
material. However,
material.
a more modest
However, other
other uses
uses of granite
granite allowed a
operation to continue until the
the pit
pit was
was closed
closed in
in 1931.
1931. By this
time, the
the quarry
quarry occupied
occupied 77 acres
acres and extended downward to aa depth
time,
depth
of 200
of
200 feet.
feet.
As the name of the town indicates,
indicates, the rock
rock exposed here is a
reddish granite.
reddish
granite. It is
and granophyric
granophyric in
in texture,
texture,
is fine-grained and
and leucocratic
leucocratic in
in composition,
composition, with quartz
quartz and alkali feldspar
and
feldspar
comprising 90% to 98% of the
the rock.
rock. Subordinate minerals include
biotite (altered
(altered to
to chlorite),
chlorite), sphene,
muscovite, and
sphene, hornblende,
hornblende, muscovite,
zircon.
zircon. This granite,
granite, like others exposed in
in this
this general
general area,
area, is
is
dated
dated at
at 1765
1765 m.y.
m.y. old.
old. A
A well-exposed,
well-exposed, greenish-black, vertical
vertical
dike of fine—grained
fine-grained metabasalt trends
trends northeasterly across
across the
the lake.
lake.
This dike is about 5 feet
feet wide,
wide, and it
it has sharp
sharp contacts
contacts with
with the
the
granite.
granite.
The Precani1rian
bedrock at
at this locality
Precambrian bedrock
locality was polished
polished and
and striated
striated
by
by westerly
westerly moving
moving Woodfordian
Woodfordian ice.
ice.
27.7
27.7
(0.3)
(0.3)
28.0
28.0
(0.1)
(0.1)
28.1
28.1
(0.1)
(0.1)
28.2
28.2
(0.1)
(0.1)
28.3
28.3
Enter
Enter the
the village
village limits
limits of
of Lohrville,
Lohrville, once aa thriving
thriving center
center for
for
granite
granite quarrying.
quarrying. County NN turns
turns south.
south.
County
County NN turns
turns west.
west. An
An abandoned,
abandoned, small
small quarry
quarry north
north of
of the
the road
road
exposes
exposes aa medium—to
medium-to coarse—grained,
coarse-grained, reddish
reddish granite.
granite.
The
The Lohrville
Lohrville Stone
Stone Company
Company north
north of
of the
the highway
highway occupies
occupies aa building
building
constructed
constructed from
from local
local granite.
granite. The
The piles
piles of
of glacial
glacial erratics
erratics
gathered
gathered together
together by
by this
this firm
firm suggest
suggest that
that these
these are
are aa more
more
important
important commodity
commodity today
today than
than the
the local
local bedrock.
bedrock.
County
County NN turns
turns south.
south. The
The large,
large, glacially-smoothed
glacially-smoothed knob
knob of
of granite
granite
north
of
the
highway
establishes
that
Pleistocene
deposits
north of the highway establishes that Pleistocene deposits are
are thin
thin
in
in this
this area.
area.
Depart
Depart Lohrville
Lohrville as
as County
County NNturns
turns westward.
westward.
(0.8)
(0.8)
14
14
Mileages
Mileages
29.1
29.1
(0.6)
(0.6)
STOP
STOP 11 at
at Flynn's
Flynn's Quarry
Quarry County
County Park
Park south
south of
of the
the highway.
highway. This
This
park,
park, like
like the
the one
one at
at Redgranite,
Redgranite, is
is developed
developed around
around aa flooded
flooded
granite quarry.
quarry. The
The park
park road
road is
is an
an old
old quarry
quarry road,
road, which
which loops
loops
granite
around
around the
the lake
lake before
before returning
returning to
to County
County Highway
Highway N.
N.
Details
Details on
on the
the geology
geology at this stop are described by Eugene Smith
Smith
in
in the
the next
next section
section of
of this
this guidebook.
guidebook. Unfortunately,
Unfortunately, only
only
30
30 minutes is
is available
available to
to examine
examine this
this interesting
interesting locality:
locality~
After
After stopping,
stopping, continue
continue westward
westward on
on County
County N.
N. The
The route
route ahead
ahead
passes
passes through
through aa low
low area
area occupied
occupied by
by tamarack
tamarack bogs
bogs before
before ascending
ascending
to
to higher, better-drained,
better-drained, Woodfordian
Woodfordian ground
ground moraine.
moraine.
29.7
29.7
(0.5)
(0.5)
County
County N
N turns
turns southward
southward along
along an
an irregular,
irregular, rolling
rolling morainal
morainal ridge.
ridge.
The
The till
till is
is studded
studded with large,
large, locally—derived
locally-derived granitic
granitic erratics.
erratics.
30.2
30.2
(0.2)
(0.2)
Enter community
community of
of Spring
Spring Lake.
Lake.
Enter
30.4
30.4
(0.3)
(0.3)
Junction County
County NNand
in Spring
Spring Lake.
Lake.
Junction
and FF in
30.7
30.7
(4.1)
(4.1)
County NN turns
turns west.
west.
Turn northward
northward on
on N.
N.
County NNand
Z. Turn southwesterly on N
N and
and leave
leave Spring
Spring
Junction County
and Z.
Lake,
Lake, through an area of rolling sandy till
till within the
the Woodfordian
complex. Large glacial erratics of
of local
local derivation
derivation are
are
morainal complex.
common in the fields
fields adjacent to the highway,
highway, and
and several
several kettle
kettle
lakes
general area.
area.
lakes are present in this general
The attractive countryside between here and
and Neshkoro is
is part of
of
As
such,
Green Lake
Lake recessional
recessional moraine.
moraine. As such, it
it has
the Woodfordian Green
little value
value for
agriculture, but
but it is
little
for agriculture,
is highly prized as recreational
land
for
city
dwellers
who
want
to
be
land for city dwellers who want to be weekend "tree farmers."
farmers." The
The
pine plantations that enhance this landscape are
the
are the result
result of
of their
their
endeavors.
34.8
(0.5)
(0.5)
Pine Bluff
Bluff
Enter Marquette County. Pine
Waushara/Marquette county
county line.
line.
This
prominent
landmark
is located about 33 miles west of
is
of here.
here.
landmark is
is
a
glacially-smoothed,
elliptical
knob
of
coarse-grained,
a glacially-smoothed, elliptical knob
coarse-grained, gray to
pinkish granite
granite that
that rises
rises more
more than
than 100 feet
above the swampy
pinkish
feet above
The granite of this
lowlands
River. The
this inlier is lithlowlands along the White River.
related
to
the
granites
exposed in
in the
the
ologically and genetically
genetically related to the granites exposed
Redgranite-Lohrville and Montello areas.
Redgranite-Lohrville
areas.
Glacial striations
striations on
on the
the bedrock
bedrock at
at this
this locality
locality trend
trend about
about
Glacial
N65°W.
35.3
35.3
(0.7)
(0.7)
in an
an area
area
Turn west
west on
on County
County Nand
N and E in
Junction
Nand
E. Turn
Junction County N
and E.
where sand
sand dunes
dunes formed
where
formed on top of the
the sandy Woodfordian drift.
drift.
36.0
36.0
(0.5)
(0.5)
Junction County
County Nand
N and E with Wisconsin 73.
Junction
73.
and
E.
and County
County E.
36.5
36.5
(0.7)
(0.7)
Cemeteries on
on both
both sides
sides of
of the
the highway
highway provide
provide ample
ample evidence
evidence of
Cemeteries
the monument-quality
monument-quality of central Wisconsin granites.
the
granites.
15
15
Turn south
south on
on State
State 73
73
Turn
Mileages
Mileages
37.2
37.2
Cross White
White River in downtown Neshkoro.
Cross
(0.4)
(0.4)
37.6
37.6
(1.3)
(1.
3)
38.9
38.9
Junction Wisconsin 73,
Junction
73, and County E
E and
and N.
N. Turn west on EE and
and N.
N.
The route
route ahead
ahead leaves
leaves the
the lowland
lowland occupied
occupied by
by the
the White
White River and
The
traverses aa scenic,
scenic, rolling
rolling upland
upland within
within the
the Woodfordian
Woodfordian morainal
traverses
complex.
complex.
and E.
Junction County
County NNand
E.
Continue west on E.
Continue
E.
(1.6)
(1.
6)
40.5
40.5
(2.6)
There are
are several kettle lakes
There
lakes of various sizes developed nearby in
in
sandy, glacial outwash. This
This is
is another
another region
region with
with low agriculagriculsandy,
tural potential,
potential, which
which is
is rapidly
rapidly being
being converted to
to recreational
tural
recreational
!Ifarms
"farms."
43.1
43.1
(0.4)
Junction County E and
and Wisconsin
Wisconsin 22.
22.
43.5
43.5
(0.6)
Wisconsin granite
granite headstones
headstones dominate the cemetery east of
Central Wisconsin
the highway.
44.1
44.1
(0.3)
Junction County E and Wisconsin
Wisconsin 22. Continue south
south on
on 22.
22. The
route ahead
ahead traverses
traverses sandy,
sandy, rolling,
route
rolling, Woodfordian ground moraine.
moraine.
44.4
44.4
(4.0)
(4.
0)
48.4
(2.9)
(2.9)
51.33
51.
(1.6)
(1. 6)
52.9
52.9
Turn
22.
Turn south on E and 22.
Cross Mecan River,
River, one of many fine
fine trout
trout streams
streams in
in central
central
Wisconsin.
Peat swamps along the highway were drained and
and developed
developed as
as muck
muck
farms.
The route
traverses a
The
route ahead traverses
a stony till formed into broad,
broad,
low drumlins with aa general
general east—west
east-west orientation.
orientation. This better—
betterdrained land
supports aa growth of pine and
land supports
and cedar.
cedar.
The sand and gravel pit east of the
the road
road is
is developed
developed in
in Woodfordian
Woodfordian
outwash.
outwash. Kettles are
are also
also present
present in
in this
this area.
area.
Enter the
the city
city of
of Montello.
Montello.
(0.5)
(0.5)
53.4
53.4
(0.3)
(0.3)
53.7
53.7
(0.1)
(0 .1)
Junction of
of Wisconsin
Wisconsin 22
22 with
with 23
23 in
in Montello.
Montello.
22
22 and
and 23.
23.
Turn west on Wisconsin
Quarries north of the
the highway exploited aa ridge
ridge of
of finefine- to
to mediummediumgrained,
red
to
grayish—red
granite
to
produce
monument
stone,
grained, red to grayish-red granite to produce monument stone,
paving
paving blocks,
blocks, building
building stone,
stone, and
and crushed
crushed rock.
rock. When
When this
this granite
granite
was
was selected
selected for
for the
the tomb
tomb of
of U.S.
u.s. Grant
Grant in
in New
New York
York City,
City, business
business
boomed.
activity peaked,
peaked, with
with some
some 200 workers employed.
boomed. By 1910,
1910, activity
employed. In
In
later
later years,
years, business declined until the
the last
last quarry
quarry closed
closed in
in 1976,
1976,
after nearly
nearly 100
100 years
years of
of operation.
operation. The
The longevity
longevity of
of operations
operations at
at
this locality
locality was facilitated
facilitated by well—developed
well-developed vertical
vertical joints
joints that
that
allowed the
the rock
rock to
to be
be removed
removed in
in large
large "precut"
"precut" blocks.
blocks.
The granite of this
this inlier is granophyric and leucocratic like
area and
and at
at Pine
Pine Bluff.
Bluff. It
It
those
those exposed in
in the
the Redgranite-Lohrville
Redgranite-Lohrville area
is
is also
also of
of the
the same
same age
age (1765
(1765 m.y.
m.y. old).
old). Several
Several near-vertical
near-vertical dikes
dikes
16
16
Mileaqe
of
of greenish-black,
greenish-black, fine-grained
fine-grained metabasalt
metabasalt up
up to
to 55 feet
feet thick
thick cut
cut
the
the granite,
granite, and
and are
are well
well exposed
exposed in
in the
the quarries.
quarries.
Well
monadnock
Well drilling
drilling adjacent
adjacent to
to the
the granite
granite ridge
ridge discloses
discloses that
that this
thismonadnock
stood
stood more
more than
than 200
200 feet
feet above
above the
the general
general level
level of
of the
the Precambrian
Precambrian
surface
surface prior
prior to
to transgression
transgression of
of the
the Late
Late Cambrian
Cambrian sea
sea (see
(see article
article
by
by Eugene
Eugene I.
I. Smith
Smith in
in this
this guidebook).
guidebook).
Glacial
Glacial striae
striae on
on the
the bedrock
bedrock surface
surface indicate
indicate
ice moved westerly
westerly across
across this
this area.
area.
ice
53.8
53.8
(0.5)
(0.5)
54.3
54.3
(0.4)
(0.4)
Junction Wisconsin
Wisconsin 22
22 and
and 23.
23.
Junction
that
that the
the Woodfordian
Woodfordian
Turn
Turn south
south on
on State
State 22.
22.
Cross the
the Fox
Fox River
River once
once
Cross
again.
again. The
The Fox flows
flows northeasterly
northeasterly to
to reach
reach
Lake Winnebago,
Winnebago, and
and ultimately Lake
Lake Michigan at
at Green
Green Bay.
Bay. We
We first
first
crossed it
it about
about 46
46 miles
miles ago,
ago, at
at Omro.
Omro.
The Fox was part of the historic canoe
canoe highway
highway across
across Wisconsin.
Wisconsin.
Although used
used by
by Indians
Indians for
for centuries,
centuries, it
it was
was "popularized"
"popularize& by
Marquette and
and Joliet on their
their historic journey
journey from
from Lake
Lake Michigan
Michigan
A
flood
of
explorers,
missionaries,
trappers,
Mississippi. A flood
trappers,
to the Mississippi.
The Fox is dammed just
and traders
traders soon
soon paddled
paddled after
after them.
them.
just upstream
and
and enlarge
enlarge Buffalo
Buffalo Lake.
Lake. Thelocks
The locks visible from
from here to deepen and
the highway were part of
of a
a navigation scheme
scheme originally
originally designed
designed
to link the
the North Atlantic (via
the
Great
Lakes)
with
the
Gulf of
(via
Lakes)
Shifting
Mexico (via
the
Wisconsin
River
and
the
Mississippi).
(via the Wisconsin River and the Mississippi).
Shifting sandsandbars along the
shallow
Wisconsin
River
ruled
against
this
the
River ruled against this plan
plan from
from
the beginning.
1.5
A canal at
Portage, Wisconsin was started in 1838 to eliminate the
at Portage,
the 1.5
mile land bridge between the headwaters of the Fox and the Wisconsin
mile
This project was finally completed in 1876,
River.
1876, but the cost of
maintaining a
a channel in the Wisconsin River proved prohibitive,
prohibitive, and
and
soon abandoned.
abandoned.
the project was soon
54.7
(1.
8)
(1.8)
56.5
(1.
7)
(1.7)
58.2
58.2
(1.
5)
(1.5)
into an
an
Leave Montello and
Leave
and the
the lowland
lowland along
along the
the Fox
Fox River,
River, and proceed
proceed into
area
ground moraine.
moraine.
area of rolling,
rolling, Woodfordian ground
The prominent,
prominent, wooded
wooded hill
hill about
about 44 miles
miles to
to the
the southwest
southwest is
is
The
Observatory Hill,
Hill, the highest point in
with an
an
Observatory
in Marquette
Marquette County,
County, with
This will
will be the locale of our
elevation
feet.
This
our second
second stop.
stop.
elevation of 1080 feet.
deposited in
The
in aa
The truck
truck farms
farms in
in this
this flat
flat area
area utilize
utilize fertile
fertile soils
soils deposited
glacial lake,
lake, which
which formed
formed when
when northeasterly
northeasterly drainage
drainage was
was blocked
glacial
by
ice.
by the
the retreating Woodfordian ice.
59.7
59.7
(0.2)
(0.2)
We will
will return
return to this
Junction
B. We
this interJunction Wisconsin 22 and County B.
loop.
section in
in aa few
few hours,
hours, and
and go
go east
east on
on BB after
after making
making aa large
large loop.
section
outwash.
Continue south
south on
on State
State 22
22 in
in an
an area
area of
of pitted
pitted sandy
sandy outwash.
Continue
purity of
of
Gravel
Gravel pits
pits in
in this
this area
area are
are testimony
testimony to
to the
the water-washed
water-washed purity
these
these deposits.
deposits.
59.9
59.9
(0.9)
(0.9)
Our
Turn east on Gem Road.
Junction
22. Turn
Road. Our
Junction Gem
Gem Road
Road and Wisconsin 22.
southwest
immediate destination
destination is
is Observatory
Observatory Hill,
Hill, about
about 22 miles
miles southwest
immediate
17
17
Mileages
Mileages
of here.
here. To
To
of
and
approach
and approach
reach our
our objective,
objective, we
we must
must circle
circle this
this promontory,
promontory,
reach
from the
the west.
west.
A small
small kettle is located northwest
northwest of
of the
the highway.
highway.
60.8
60.8
(1.4)
(1.4)
Large glacial
glacial erratics
erratics of
of local
local derivation
derivation litter the field north of
Large
the road.
the
road.
62.2
62.2
(0.2)
Junction 14th Road and Gem Road.
Junction
Road.
62.4
62.4
(1.0)
Junction 14th Road and 13th Road. Turn
Junction
(left) on 13th Road
Turn south (left)
in an
an area of rolling ground moraine. At long last,
in
last, we are closing
in on Observatory
Observatory Hill!
in
Hill~
63.4
63.4
(0.5)
An irrigation well west of the road encountered Precambrian
Precambrian porphyritic rhyolite,
rhyolite, lithologically identical to
to exposures
exposures on
on
Observatory Hill,
Hill, at a
a depth of
of 300
300 feet.
feet.
63.9
63.9
(0.4)
(0.4)
64.3
64.3
(1.1)
(1.1)
Turn
(left) on 14th Road.
Road.
Turn west
west (left)
-
Junction 13th Road and Gillette Ave.
Ave. Proceed southeasterly (straight
(straight
ahead) on
on Gillette
Gillette Ave.
Ave. and ascend the
ahead)
the flank
flank of Observatory Hill.
Hill.
STOP 22 for
for Observatory
Observatory Hill rhyolite.
STOP
rhyolite. This bedrock hill,
hill, which rises
rises
about 250
above the
level of the surrounding landscape,
about
250 feet
feet above
the level
landscape, has aa
core of resistant
core
resistant rhyolite
rhyolite flanked by medium—to
medium-to coarse—grained,
coarse-grained,
friable,
friable, iron-stained Upper
Upper Cambrian
Cambrian sandstone.
sandstone. Locally,
Locally, this sandgrades into a
stone grades
a conglomerate that contains clasts derived from
from
the Precambrian bedrock.
the
bedrock.
Glacial striae on the rhyolite vary from N45W to N74W,
Glacial
N74W, and record
record
the movement of ice over and around this resistant knob.
the
knob.
A
A detailed description of the
the rocks
rocks at
at this
this locality
locality is
is provided
provided by
by
Eugene Smith
Smith in
in the
the next
next section
section of
of this
this guidebook.
guidebook. Since only 60
60
minutes is
is allocated for
for this
this stop,
stop, we should
should proceed
proceed with
with
enthusiasm:
enthusiasm~
NOTE:
Since this road dead ends
ends about
about 0.4 mile ahead, backtrack northwesterly to
to the
the intersection
intersection of
of Gillette
Gillette Road
Road and
and 13th
13th Road.
Road. The
logged mileage that follows
follows' assumes a turn—around
turn-around at the
the dead end
end
of Gillette
Gillette Road
Road after
after this
this stop.
stop.
a
65.4
65.4
(0.7)
(0.7)
66.1
66.1
(0.2)
(0.2)
66.3
66.3
(0.4)
(0.4)
66.7
66.7
(1.5)
(1.5)
Intersection of Gillette Road
Road and
and 13th
13th Road.
Road. The bedrock
bedrock of
of the
the high,
high,
wooded hill west of
of this
this intersection
intersection is
is Upper Cambrian
Cambrian sandstone
sandstone
with no
no rhyolite
rhyolite exposed.
exposed. Turn south
south on
on 13th
13th Road.
Road.
13th
13th Road
Road turns
turns sharply
sharply to
to the
the west
west in
in an
an area
area of
of rolling
rolling countryside
countryside
formed by aa Woodfordian
Woodfordian recessional
recessional moraine.
moraine Pine plantations, cedars,
cedars,
and oaks accentuate
accentuate the
the beauty
beauty of
of this
this glacial
glacial landscape.
landscape.
Junction
Junction 13th
13th Road
Road and
and Gillette
Gillette Drive.
Drive. Continue
Continue west
west on
on Gillette.
Gillette.
NOTE:
NOTE: It
It seems
seems that
that the
the Gillettes
Gillettes are
are important
important in
in this
this country!
country~
AA low
low bedrock
bedrock ridge
ridge north
north of
of the
the road
road is
is the
the Taylor
Taylor Farm
Farm rhyolite
rhyolite
locality.
porphyritic rhyolite exposed here
locality. The
The well-jointed,
well-jointed, porphyritic
here is
is
18
18
Mileages
Mileages
similar
similar to
to that
that found
found on
on Observatory
ObservatoryHill.
Hill. However,
However, the
the high
high bedbedrock
rock hill
hill of
of sandstone
sandstone northeast
northeast of
of here
here separates
separates these
these two
two
localities. Glacial
Glacial striae
striae on
on this
this rhyolite
rhyolite document
document aa general
general
localities.
N70W
N70W direction
direction of
of ice
ice flow
flow for
for the
the Green
Green Bay
Bay lobe
lobe of
of Woodfordian
Woodfordian
ice at
at this
this locality.
locality.
ice
Turn
Turn south
south on
on County
County F.
F.
68.2
68.2
(0.2)
(0.2)
Junction
Junction Gillette
Gillette Drive
Drive and
and County
County F.
F.
" 68.4
68.4
LUNCH STOP
STOP at
at John
John Muir
Muir County
County Park
Park on
on Ennis
Ennis Lake.
Lake.
LUNCH
(1. 4)
(1.4)
John
John Muir,
Muir, aa distinguished
distinguished naturalist
naturalist and
and aa prime
prime mover
mover in
in the
the
establishment
establishment of
of our
our national
national park
park system
system in
in 1890,
1890, was
was born
born in
in
His
family
came
to
Wisconsin
to
farm
the
land
Scotland
in
1838.
His
family
came
to
Wisconsin
to
farm
the
land
Scotland in 1838.
he
was
only
a
boy
of
across
the
lake
from
this
memorial
park
when
he
was
only
a
boy
of
across the lake from this memorial park when
Fountain
Lake
11.
He
grew
up
on
this
beautiful
kettle
lake
(called
Fountain
Lake
He grew up on this beautiful kettle lake (called
11.
ingredient
in
the
in
those
days),
and
it
proved
to
be
a
significant
ingredient
in
the
in those days), and it proved to be a significant
development
of
his
love
of
nature.
development of his love of nature.
The
The importance
importance of
of this
this lake
lake to
to Muir
Muir is
is well
well documented
documented on
on page
page 96
96
Youth"
(University
of his autobiography,
autobiography, "The
"The Story of My Boyhood
Boyhood and
and Youth" (University
Press, 1965).
1965).
of Wisconsin Press,
"Our beautiful
beautiful lake,
lake, named Fountain Lake by father,
father, but Muir's
Muir's Lake
Lake
lakes
by the neighbors,
neighbors, is one of the many small
small glacier
glacier lakes that
that adorn
adorn
It is
Wisconsin landscapes.
landscapes.
is fed by twenty or thirty meadow
the Wisconsin
surrounded by
by
springs, is
is about
about half a
mile long,
wide, and surrounded
springs,
a mile
long, half as wide,
meadows
low finely-modeled
hills
dotted
with
oak
and
hickory,
and
finely-modeled hills
hickory,
meadows
and ferns.
full of grasses
ferns.
full
grasses and
and sedges
sedges and many beautiful orchids and
First there
a zone
rushes, and just
just beyond
beyond the
the
there is
is a
zone of green,
green, shining rushes,
fifty or
or sixty
rushes
sixty feet
feet
rushes aa zone
zone of
of white
white and orange
orange water-lilies fifty
On bright days,
forming aa magnificent
magnificent border.
border.
days, when the lake
wide forming
sun—spangles
danced together
together
breeze, the lilies
lilies and
and sun-spangles danced
was rippled by a breeze,
between
in radiant
radiant beauty,
beauty, and
and it
it became
became difficult
difficult to
to discriminate
discriminate between
in
them.
them.
and Bible-lessons,
Bible—lessons,
On
chores and sermons and
On Sundays,
Sundays, after or before
before chores
especially
in
lily time,
we
the lake
lake for
for hours,
hours, especially in lily
time,
we drifted about on the
ducks,
getting finest
finest lessons
lessons and
and sermons
sermons from
from the
the water
water and flowers,
getting
flowers, ducks,
In particular
particular we
we took
took Christ's
Christ's advice
advice and
and
fishes,
fishes, and
and muskrats.
muskrats. In
they grow
grow up
up in
in beauty
beauty out
out
how they
devoutly
devoutly "considered the lilies" -- how
ideglOri0USlY
among
the
breezy
sun-spangles."
of
of gray
gray lime
lime mud,
mud, and
and ride gloriously among the breezy sun-spangles."
of rolling,
rolling,
After lunch,
lunch, continue
continue south
south on
on County
County FF through
through an
an area of
After
Immediately to
to the
the west,
west, the
the north-flowing
north-flowing Fox
Fox River
River
sandy
sandy drift.
drift. Immediately
parallels
parallels the
the highway.
highway.
69.8
69.8
(1.
7)
(1.7)
The rolling,
rolling, sandy,
sandy,
Turn east
east on
on County 0.
Junction
O. Turn
o. The
Junction County
County F and 0.
Differences
ground moraine
moraine contains
contains large
large erratics
erratics scattered about.
ground
about. Differences
with tamaracks
tamaracks
in
in drainage
drainage are
are clearly
clearly reflected
reflected in
in the vegetation,
vegetation, with
the
higher,
well—
in
in swampy
swampyplaces,
places,and
andoaks
oaksand
andplantation
plantation pines
pines on
on the higher, welldrained
drained soils.
soils.
19
19
Mileages
Mileages
71.5
71.
5
(1.4)
(1.
4)
72.9
72.9
Junction County
County 00 and
and 13th
13th Road.
Road.
Junction
Turn
Road.
Turn south
south on
on 13th Road.
Knights Lake,
Lake, on
on the
the east
east side
side of
of the
the road,
road, occupies
occupies aa small
Knights
small kettle.
kettle.
(0.7)
(0.7)
73.6
73.6
(0.4)
(0.4)
Junction 13th Road and 14th Road.
Junction
Road. Turn
(right) on 14th Road.
Road.
Turn south
south (right)
This road
road curves
curves eastward immediately ahead.
This
ahead.
74.0
74.0
(0.9)
(0.9)
Junction 14th
14th Road
Road and
and Dalton
Dalton Road
Junction
Road at
at the
the Marquette/Columbia
Marquette/Columbia county
line.
Turn south
south (right)
on Dalton
Dalton Road
Road and
and enter
enter Columbia County,
County,
line.
Turn
(right) on
through rolling
rolling country
country with
with some
some land
land suitable
suitable for
agriculture.
through
for agriculture.
74.9
74.9
(0.2)
(0.2)
Junction Dalton
County CM.
CM.
Junction
Dalton Road
Road arid
and County
Turn
(right)
Turn southwesterly (right)
County CM
CM in
in an
an area with abundant erratics.
County
erratics. We
will
backtrack
We will
this intersection after Stop 3.
this
3.
75.1
75.1
(0.4)
(0.4)
well on
on the
the A.
A. Uchtung farm on the right side of the road reached
A well
Precambrian rhyolite at
at aa depth
depth of
of 390
390 feet.
feet. Drilling continued 170
feet
into
the
rhyolite.
feet into the rhyolite.
75.5
75.5
(0.6)
(0.6)
76.1
76.1
(0.1)
(0.1)
76.2
76.2
(0.7)
(0.7)
Junction County CM and
and Monthey
Monthey Road.
Road.
Road.
Road.
on
to
Turn south (left)
(left) on Monthey
Exposure
road.
Exposure of Middle
Middle Precambrian Marcellon rhyolite east of the road.
This is
is one
one of four
This
four isolated exposures of rhyolite in this immediate
immediate
area.
area.
STOP 33
at Marcellon rhyolite locality.
STOP
locality. This scenic exposure is
is aa
70 feet
feet above
above
glacially rounded and polished knob that rises nearly 70
the surrounding
surrounding countryside.
countryside. Glacial striae indicate aa westerly
direction for
for Woodfordian
Woodfordian ice
ice flow
flow at
at this
this locality.
locality.
A
A detailed description of
of the geology
geology to
to be
be observed
observed here
is
is supplied
supplied by Eugene Smith
Smith in
in the
the next
next section
section of
of this
this guidebook.
guidebook.
only 45
45 minutes for
for an
an examination
examination of
of this
this
Unfortunately, we have only
interesting
interesting exposure.
exposure.
After studying
studying the
the rock
rock here, turn
turn around
around and
and backtrack
backtrack northward
northward
along
along Monthey
Monthey Road.
Road.
76.9
76.9
Junction
Junction Monthey
Monthey Road
Road and
and County
County CM.
CM.
Turn northeast
northeast (right)
(right) on
on CM.
CM.
Turn
(0.6)
(0.6)
77.5
77.5
(2.7)
(2. 7)
80.2
80.2
(0.6)
(0.6)
80.8
80.8
(0.2)
(0.2)
Junction
Junction CM
CM and
and Dalton
Dalton Road.
Road. Continue
Continue northeastward
northeastward on
on CM
CM through
through
rolling,
rolling, glacial
glacial countryside.
countryside.
Junction
Junction County
County CM
CM and
and Wisconsin
Wisconsin 22.
22. Turn
.=T:.. :u:.::r:..:.n=-.north
. :n.:.:o::..:r=.t.=.h:..:. . .(left)
--'(.=1:.. :e:.. :f::..:t"-'):.. .-o::.on
.:n:..:. . . =State
S:.. :t:..:.a::..:t::..:e::.. . .22
. :2::..:2=.
and
and cross
cross Columbia/Marquette
Columbia/Marquette county
county line.
line. Enter
Enter Marquette
Marquette County
County
once
once again.
again.
State
State Historical
Historical Marker
Marker on
on the
the east
east side
side of
of the
the highway
highway is
is entitled
entitled
"John
"John Muir
Muir Country,"
Country," and
and it
it describes
describes his
his sojourn
sojourn in
in this
this area.
area. It
It
also
also includes
includes this
this meaningful
meaningful quote
quote of
of Muir's:
Muir's:
20
20
Mileages
Mileages
"Everybody needs beauty as well as
as bread;
bread;
places to
play
in
and
places
to
pray
to
in and
to pray in,
in,
where nature may heal
heal and
and cheer,
cheer, and
and give
give
strength to body and
and soul
soul alike."
alike."
81.0
(1.
2)
(1.2)
The house
house west of the
fieldstone, the trade
82.2
(3.6)
Wisconsin 22
22 climbs
climbs onto a
a highland littered
littered with
with glacial
glacial erratics.
erratics.
85.8
(3.5)
road
name
is a
a showplace for samples of Wisconsin
for
for glacial
glacial erratics.
erratics.
Junction Wisconsin
Wisconsin 22
22 and
and County
County B.
B. Turn east on County B, in
in a
a
region of sandy outwash
outwash occupied
occupied by
by gravel
gravel pits.
pits. The route ahead is
is
numerous swamps,
characterized by numerous
swamps, some of which are drained for muck
farming. Higher areas support
support pine
pine plantations.
plantations.
89.3
(0.7)
Marquette/Green
Marquette/Green Lake
Lake county
county line.
line.
Enter Green Lake
Lake County.
County.
90.0
(3.1)
(3.1)
The poorly drained lowland
lowland north of
of the
the road
road is
is part
part of
of the
the extenextensive Grand River Wildlife Area.
Area. When the retreating Woodfordian ice
dammed the
the northeastward flowing
flowing drainage
drainage of
of the
the Fox
Fox and
and Grand
Grand rivers,
rivers,
In time,
time, it filled with meltaa glacial lake formed
formed in
in this
this area.
area. In
water,
westward into
water, and overflowed westward
into the
the Wisconsin River.
River. However,
continued retreat of the Green Bay lobe
lobe of the Woodfordian ice redrainage, and this lake was emptied.
However, Lake
stored northeasterly drainage,
emptied. However,
Puckaway and
and Buffalo Lake
Lake exist
exist as
as remnants
remnants of
of this
this ancient
ancient water
water body.
body.
93.1
Junction County
and H..
Junction
County BBand
H.
Continue northeasterly (left)
(left) on
on BBand
H.
and H.
(0.3)
93.4
(2.4)
95.8
(0.5)
(0.5)
96.3
(0.3)
and H.
Junction County B
Band
H. Turn north
north on
on County
County H.
H. The high,
high, wooded
hill to the northeast of this
this intersection
intersection is
is Bartholomew
Bartholomew Bluff.
Bluff. It
It
is a
is
a bedrock feature
feature composed of Upper Cambrian formations
formations capped
by resistant Lower Ordovician dolomite
dolomite of
of the
the Prairie
Prairie du
du Chien
Chien Group.
Group.
The route ahead traverses the
the east
east edge
edge of
of an area of
of poorly—drained,
poorly-drained,
glacial lake
deposits now occupied by the Grand River Marsh.
glacial
lake deposits
Marsh.
The bedrock hill immediately northwest of the
the road
road is
is one of several
isolated rhyolite exposures,
exposures, which trend northwestward from
from here for
for
about
one
mile.
about one mile. In
In all,
all, there
there are
are seven rhyolite knobs
knobs in this general
area.
area. These features
features stood several hundred feet
feet above
above the
the general
general Precambrian erosional level as monadnocks,prior to transgression of
of the
the
Upper Cambrian sea (see
(see article by Eugene I.
I. Smith in this guidebook).
guidebook).
STOP 4
STOP
4 at an exposure of the
the Marquette
Marquette rhyolite.
rhyolite. The cedar-covered,
cedar-covered,
glacially-smoothed, bedrock
bedrock knob west of the highway rises about
glacially-smoothed,
100 feet
above poorly-drained tamarack swamps to the north.
100
feet above
north. A
A similar
exposure lies immediately east
east of
of the
the road.
road.
Glacial striations and chatter marks on the bedrock indicate
indicate that
that the
the
Woodfordian ice generally moved westward at this locality.
locality. However,
measurements vary
vary from
from N57W
N57W to
to N86W.
N86W.
analysis of
of the
the rhyolite
rhyolite at
at this
this stop
stop is
is provided
provided by
by Eugene
Eugene Smith
An analysis
in the next section
section of
of this
this guidebook.
guidebook. About 60
60 minutes are available
to study the
the exposures
exposures at
at this
this locality.
locality.
21
Mileages
After examining the rhyolite,
rhyolite, continue northeasterly on County H.
H.
96.6
(1.0)
(1.
0)
97.6
(3.8)
KK. Turn
Turn east (right)
and KK.
Junction County H
H and
and KK.
(right) on H
Hand
KK. The route
ahead traverses
traverses rolling
rolling ground
ground moraine
moraine studded with
with numerous
numerous erratics.
erratics.
ahead
The shape of the east—west
east-west trending drumlin south of the road
road estab—
establishes that ice movement in this area
lishes
area was
was to
to the
the west.
west.
Junction County H,
Continue straight ahead (east)
H, KK,
KK, and
and B.
B. Continue
(east) on
County H. The route ahead traverses scenic,
County
scenic, glacial countryside
countryside with
some agricultural potential.
some
potential. Lake
Lake Puckaway,
Puckaway, an
an enlargement of the
Fox River,
River, is occasionally
occasionally visible
visible to
to the
the north.
north.
101.4
(2.1)
Junction County HH and
Wisconsin 73. Turn south (right)
and Wisconsin
(right) on State
State 73.
73.
The route ahead traverses
traverses rolling
rolling agricultural
agricultural land.
land.
103.5
(0.3)
Junction Wisconsin 73
73 and
and 44.
44.
103.8
(0.6)
Enter Manchester,
Manchester, a
a hilltop community astride the
the Green Lake
Lake recessional
recessional
moraine. This prominent glacial feature,
feature, which trends
trends north-northwestnorth-northwestward and south—southeastward
south-southeastward from
from here,
here, formed
formed as
as the
the Green Bay
Bay lobe
lobe
of the Woodfordian ice paused
paused during
during retreat.
retreat.
104.4
104.4
(0.4)
Leave Manchester in an
an easterly
easterly direction.
direction. The boundary between two
major physical provinces trends
trends northeast—southwest
northeast-southwest through
through this
this area.
area.
The Central Plain,
Plain, to the
northwest, is a
The
the northwest,
a subdued region characterized
by Upper
Upper Canibrian
Cambrian bedrock.
The Eastern Ridges and Lowlands,
Lowlands, with
younger bedrock, occupies the
the region
region to
to the
the east
east and
and southeast.
southeast.
However, this
However,
this division is ill—defined
ill-defined here because of the thick cover
cover
of young glacial
glacial deposits.
deposits.
104.8
(0.4)
(0.4)
Junction Wisconsin 73
73 and
and 44.
44.
rolling agricultural
agricultural land.
land.
105.2
105.2
Cross Grand River.
River.
Continue south on 73
73 and
and 44.
44.
Turn south on State 73 in an area
area of
(1.6)
(1. 6)
106.8
106.8
(0.7)
(0.7)
The highway intersects
intersects aa drumlin
drumlin that
that trends
trends east-west.
east-west. The blunter,
east—facing
east-facing nose of this drumlin indicates westerly ice
ice movement in
in
this area.
area.
107.5
107.5
Lake Maria,
Maria, east of the highway,
highway, lies
lies along the trend of the
the Green
Lake recessional moraine.
moraine.
(1.8)
(1. 8)
109.3
(0.6)
(0.6)
Green Lake/Columbia
Lake/Columbia county
county line.
line. Enter Columbia County in
in an
an area
area
where intensively farmed
farmed drumlins stand
stand above
above flat,
flat, low
low areas
areas that
that
are poorly
poorly drained.
drained. When drained,
drained, these lowlands
lowlands are
are productive
muck farms.
farms.
109.9
109.9
(2.9)
(2.9)
Several roadcuts
the next 0.5 mile expose thin-to medium-bedded
roadcuts in the
Lower Ordovician
Ordovician dolomite
dolomite of
of the
the Prairiedu
Prairie du Chien
Chien Group.
Group. Some of
of
these bedrock exposures form
form the
the cores
cores of
of drumlins.
drumlins.
112.8
112.8
(2.0)
(2.0)
The high-voltage power lines crossing the highway come
come from
from aa large,
large,
coal-fired power plant
plant at
at Portage.
Portage. This facility
facility utilizes Wisconsin
River water
water as
as aa coolant.
coolant.
22
22
Mileages
Mileages
114.8
114.8
(0.5)
(0.5)
Junction
Junction Wisconsin
Wisconsin 73
73 and
and 33.
33.
115.3
115.3
(1.0)
(1.0)
Enter Randolph.
Randolph.
Enter
116.3
116.3
(0.2)
(0.2)
Leave
Leave Randolph.
Randolph.
'116.5
ll6.5
(13.0)
(13.0)
Continue
Continue south
south on
on 73.
73.
Cross
Cross Columbia/Dodge
Columbia/Dodge county
county line,
line, as
as Wisconsin
Wisconsin 73
73 turns
turns east,
east, and
and
then south.
south. Enter
Enter Dodge
Dodge County.
County. The route
route ahead
ahead traverses
traverses rich
rich
agricultural land
land developed on a swarm
swarm of broad, well—formed,
well-formed, southsouthwesterly-trending drumlins.
drumlins.
westerly-trending
129.5
129.5
(1.3)
(1.3)
Junction Wisconsin 73
73 and
and U.S.
u.s. 151.
151.
130.8
130.8
(0.9)
(0.9)
Dodge/Columbia
Dodge/Columbia county
county line.
line. Enter Columbia County and
and the
the city
city of
of
Cross
southeasterly
flowing
Crayfish
River.
Columbus.
southeasterly
flowing
Crayfish
River.
Columbus.
131.7
131.7
(0.6)
(0.6)
Junction Wisconsin
Wisconsin 73
73 and
and 89
89 in
in Columbus.
Columbus.
Wisconsin
89.
Wisconsin 89.
132.3
132.3
(3.0)
(3.0)
Leave Columbus.
Columbus. The route
route ahead
ahead traverses
traverses intensively
intensively farmed,
farmed, rolling,
rolling,
glacial countryside.
countryside.
135.3
135.3
(4.8)
(4.8)
Columbia/Dane county
county line.
line. Enter Dane County.
County.
drumlins here trend
trend southwesterly.
southwesterly.
140.1
(1.4)
(1.4)
Dane/Dodge county
county line.
line.
drumlins.
141.5
(0.7)
(0.7)
Stop sign at junction
junction of
of Wisconsin
Wisconsin 89
89 and
and County
County T.
T.
(east) on
on Dalman
Dalman Road.
Road.
ahead (east)
142.2
(1.0)
(1.0)
Junction Dalman Road
Road and
and County
County I.
I.
143.2
(1.0)
(1.0)
village of Portland and junction with Wisconsin 19.
Village
19.
19, and
and leave
leave Portland.
Portland.
on State 19,
144.2
(0.3)
(0.3)
Cross Maunesha
Maunesha River.
River.
144.5
(0.1)
(0.1)
Knobs of
of glacially-smoothed,
glacially-smoothed, Middle
Middle Precambrian
Precambrian Waterloo Quartzite
Knobs
These exposures
exposures are
are two of
lie
lie north
north and south of the highway. These
about aa dozen
dozen quartzite
quartzite knobs
knobs that
that protrude
protrude through the
the glacial drift
about
All of the
the exposures
exposures are
are smoothed by glacial
in
area. All
in this general area.
action, and
and some
some have
have small potholes developed
action,
developed on
on the
the upper
upper surfaces.
surfaces.
This quartzite
quartzite is
is quite
quite
This
Baraboo syncline,
syncline, about
Quartzite, ripple
ripple marks
marks
Quartzite,
also present
present within
within the
also
Continue south
south on
on State
State 73.
73.
Turn south
south (left)
(left) on
on
Broad,
Broad, well-shaped
Enter Dodge County in an area with occasional
Proceed straight
Turn south (right)
(right) on County
County I.
I.
Turn northeast
to that
that exposed in the well-known
similar to
Like the
the Baraboo
35
35 miles to
to the
the northwest.
northwest. Like
cross
bedding, and conglomeratic beds are
cross bedding,
thick quartzite sequence
sequence in
in this
this area.
area.
23
23
Mileages
The structure here is an easterly plunging
The
plunging syncline.
syncline.
as at
at Baraboo,
Baraboo, may have occurred 1650
as
1650 m.y.
m.y. ago.
ago.
This folding,
folding,
Measurements of glacial striae indicate that the ice flowed
Measurements
flowed about
S2OW at
at this locality.
S20W
locality.
144.6
(0.3)
STOP 5 at
at the
the abandoned
abandoned John
John O'Laughlin
O'Laughlin quarries
quarries in
in the
the Waterloo
Waterloo
STOP
Quartzite.
The quartzite
quartzite at
this stop is described by Eugene Smith in the next
The
at this
minutes Is
section of this
this guidebook.
guidebook. About 30
30 minutes
is allotted to
assimilate the geology at
at this
this locale.
locale.
144.9
144.9
(1.7)
Junction Wisconsin 99
99 and
and Hubbleton
Hubbleton Road.
Road.
19.
Proceed east on Wisconsin
About 1 mile north along
along Hubbleton Road,
Road, in
in the
the ditch
ditch along
along the
the
eastern edge
edge of the
the road,
eastern
road, an isolated exposure of Paleozoic conglomThis conglomerate,
erate is
is present.
present. This
conglomerate, which contains rounded Waterloo
Quartzite boulders
boulders up to 66 feet
across, is probably a
Quartzite
feet across,
a local facies
facies
of the Middle Ordovician St.
St. Peter
Peter Sandstone.
Sandstone.
It is
is also one of the
few Paleozoic exposures in
in this
this general
general area.
area.
About 0.5
0.5 mile
mile straight north of the St.
About
St. Peter conglomerate locality,
locality,
at the
at
the junction of Maunesha Creek and the Crawfish River,
River, is
is Stony
Stony
Island.
This is
This
is another glacially rounded mass of Waterloo Quartzite.
Here, several pegmatite dikes
dikes up to 3.2 feet thick intruded the
Here,
quartzite after
after folding.
folding.
These dikes were dated by L.T.
L.T. Aldrich and
and
others in 1959 as
as 1444
1444 m.y. old.
old.
The route
more drumlin county,
The
route ahead traverses
traverses more
county, although the agricultural potential is
not
as
good
as
it
was
is
as good as it was east
east of
of Portland.
Portland.
146.4
146.4
(0.4)
Easterly dipping
Middle Precambrian Waterloo Quartzite adds
dipping ledge
ledge of Middle
adds
interest to
Interto the lawn of the
the farmhouse
farmhouse south of the highway.
highway.
mittent exposures indicate
indicate that
that this
this ledge
ledge persists
persists southward
southward along
along
strike for
almost
a
mile.
for almost a mile.
147.0
(0.3)
(0.3)
Another exposure of Waterloo Quartzite is
is visible
visible about
about 100
100 yards
yards north
north
of the
highway.
the highway.
147.3
(0.5)
(0.5)
Junction Wisconsin
Wisconsin 19
19 and
and County
County GG (north).
(north).
Continue east
east on
on 19.
19.
Exposures of brecciated Waterloo Quartzite cemented
cemented by
by milky
milky quartz
quartz
are located about 0.75
0.75 mile to
to the
the north.
north. Additional exposures of
quartzite are present in
in the
the vicinity
vicinity of
of Mud
Mud Lake,
Lake, about
about 55 miles
miles
north—northeast
north-northeast of
of here
here along
along County
County G.
G.
147.8
147.8
(0.5)
Dodge/Jefferson
Dodge/Jefferson county
county line.
line.
Enter Jefferson County.
County.
148.3
148.3
(2.4)
Hubbleton
Hubbleton and
and junction
junction Wisconsin
Wisconsin 19
19 and
and County
County G.
G. Turn south
south (right)
(right)
on GG in a
a broad area of flat,
flat, poorly-drained muck soils
soils located
located
between
between intensively
intensively farmed drumlins.
drumlins. Where
~ihere ditched,
ditched, the muck soils
soils
are also
also cultivated.
cultivated.
24
24
Mileages
Mileages
150.7
150.7
(2.1)
(2.1)
County
county GG continues
continues southward
southward through
through drumlin
drumlin country.
country.
152.8
152.8
(1.4)
(1.4)
The
The low
low ridge
ridge of
of Waterloo Quartzite
Quartzite in
in the
the field
field about
about 150
150 yards
yards
east
of
the
highway
is
sometimes
referred
to
as
the
Lake
east of the
is sometimes referred to as the Lake Mills
Mills
here is
is light
light blue
blue to gray in
exposure.
exposure. The
The quartzi-te
quartzite here
in color,
color, and
and
it
is
composed
almost
entirely
of
coarse,
interlocking
quartz
it is composed almost entirely of coarse, interlocking quartz
grains
grains with
with rare
rare mica.
mica. Primary
Primary foliation
foliation (bedding)
(bedding) strikes
strikes
N.
500
W.
and
dips
70°
northeast
on
the
south
N. 50° W. and dips 70° northeast on the south limb
limb of
of the
the
Waterloo syncline.
syncline.
Waterloo
154.2
154.2
(2.0)
(2.0)
Junction
Junction County
County GG and
and Wisconsin
Wisconsin 89.
89.
through good
good drumlin
drumlin country.
country.
through
156.2
156.2
(1.8)
(1.8)
Junction
Junction Wisconsin
Wisconsin 89
89 and
and Interstate
Interstate 94.
94.
Milwaukee. 1
Milwaukee.1
Turn south on Wisconsin 89
89
Turn east on 1-94
I-94 toward
toward
The 1-94
I-94 route from
from the Lake Mills-Waterloo interchange
interchange to
to Milwaukee
is entirely within the Eastern Ridges and
and Lowlands physical province,
and the highway trends at right angles to the
the general
general strike
strike of
of the
the
Paleozoic
Paleozoic formations.
formations. Consequently,
Consequently, the bedrock along
along the
the route
route
ranges from
from Middle Ordovician formations
formations on the
the west to
to Silurian
Silurian
on the
the east.
east. However,
However, these rocks
rocks are
are largely
largely obscured
obscured
dolomite on
glacial deposits.
deposits.
by Woodfordian glacial
The glacial geology encountered along
along 1-94
I-94 between here and
and Milwaukee
Milwaukee
spectacular. The orientation of the
the route
route is
is such
such that
that the
the interinteris spectacular.
state cuts
cuts most glacial
glacial features
state
features essentially at right angles.
angles. From
west to east,
east, these include well—developed
well-developed drumlin
drumlin fields,
fields, outwash
outwash
plains,
plains, the Kettle Interlobate
Interlobate Moraine with numerous scenic
scenic lakes,
lakes,
and recessional
recessional moraines
moraines of the
the Lake
Lake Border morainic system.
and
system. Other
significant attractions along
along this
this route
route include:
include: the Lapham Peak
overlook high in the Kettle Moraine,
Moraine, and
and the subcontinental
subcontinental divide,
divide,
which separates drainage destined for
for the North Atlantic via
via the
the
St. Lawrence
Lawrence from that
that which flows
to the
St.
flows to
the Gulf of Mexico via the
Mississippi.
158.0
(2.0)
(2.0)
Eastbound rest area in
in an area
area of rolling
rolling ground
ground moraine.
moraine.
160.0
(1.0)
(1.0)
1-94 crosses the Crawfish River,
I-94
River, aa tributary
tributary to
to the
the Rock.
Rock. Aztalan
In
State Park is
is 1.5 miles
miles south on the west bank of this river.
State
river.
In
addition to
to Late
Late Woodland
Woodland Indian
Indian effigy
effigy mounds,
mounds, this
this park
park contains
contains
addition
two—tiered pyramidal mound,
mound, and a
aa two-tiered
a partly restored stockaded
village identified with the
the Middle
Middle Mississippi
Mississippi culture.
culture. When the
site was
was first
first described
described in
in 1837,
1837, it
it was
was named
named Aztalan
Aztalan in the
the hope
hope
site
that the
the cultural
cultural remains
remainspreserved
here were
were those
those of Mexican
Mexican Aztecs.
Aztecs.
that
preserved here
To reach
reach the
the park,
park, use
use the
the Lake
Lake Mills
Mills exit
exit and
and then
then turn
turn east on
To
County
B.
County B.
161.0
161.0
(1.0)
Westhound rest
rest area,
area, in
in an
an area
area of ground
ground moraine
moraine and low—lying
Westbound
low-lying
drumlinoid
drumlinoid hills.
this geologic
guide
published
with with
permission
ofofKendall/
1ndof
The remainder
of this road
geologic
roadis
guide
is published
permission
Kendall/
be duplicated
duplicated by
by any
any means
means
Hunt Publishing Company,
Company, Dubuque,
Dubuque, Iowa,
Iowa, and
and it should not
not be
Hunt
without
25
without written permission.
permission.
25
Mileages
Mileages
162.0
162.0
(1.0)
(1.0)
1—94 crosses the Rock
The Rock
Rock marks
marks aa general
general vegetation
I-94
Rock River.
River.
The
divide between
between native
native hardwood
hardwood forests
forests to
to the
the east,
east, and
and oak
oak
divide
savannas and prairies to the west.
Some think
think the
the river
river formed
savannas
west.
Some
formed
barrier to
to prairie
prairie fires,
fires, thus
thus preserving
preserving the
the forests
forests to
to the
the
aa barrier
east.
east.
Jefferson, 6.5 miles
miles to
Jefferson,
to the south at the junction of the Crawfish
and Rock
Rock rivers,
rivers, experienced
experienced aa short-lived,
short—lived, geology-related,
geology—related, land
and
boom about
about 1840.
1840. A federally—assisted
federally-assisted project was planned to
to
construct aa canal
canal from
from Lake
Lake Michigan
Michigan at
at Milwaukee
Milwaukee to
to the
the Rock River
construct
Some construction
construction was
was actually
actually accomplished before
near Jefferson.
Jefferson.
Some
the million-dollar
million—dollar project was
was abandoned.
abandoned. Meanwhile,
Meanwhile, land
land values
had sky—rocketed
sky-rocketed in Jefferson as
as the prospect of a connection
the Mississippi
Mississippi River
River and
and the
the Great
Great Lakes
Lakes seemed
seemed imminent.
iminent.
between the
Land promoters arrived,
arrived, and a
a steamboat made it up the Rock River
River
from St.
St. Louis. Tracts of swampland were bought by local residents
residents
and newcomers
newcomers at
at inflated
inflated prices,
prices, in
in the
the hope
hope that
that great profits
profits
and
would result when the
the canal
canal was
was completed.
completed.
The
The land promoters
left town
town with
with well-laden
well—laden carpetbags
carpetbags before
before news
news of the
the abandonabandonleft
ment of the canal plans
plans reached
reached southern
southern Wisconsin.
Wisconsin.
163.0
(6.0)
Watertown, Johnson Creek,
Exit Wisconsin 26 to Watertown,
Creek, and Jefferson,
Jefferson,
within the Jefferson County
County drumlin
drumlin field.
field. Where the interstate
interstate
cuts through a
a drumlin,
drumlin, the roadcuts have been carefully sodded
sodded
over to conceal the internal character of the sandy and
and clayey
clayey till.
till.
However,
However, at the northwest corner of this intersection, behind the
the
service station and restaurant,
restaurant, an excavated drumlin is
is exposed.
exposed.
169.0
(4.0)
moraine assumes
assumes symmetry and order as
Irregular ground moraine
as the highway
traverses a classic drumlin field,
field, produced by the
the Green
Green Bay
Bay lobe
lobe
drumlins trend essentially
of the Woodfordian ice
ice advance.
advance. These drumlins
north—south,
north-south, but nearer to Madison the
the orientation is southwesterly.
Poorly drained areas and tamarack
tamarack swamps
swamps flank
flank many of
of the
the drumlins.
drumlins.
173.0
(2.0)
Wisconsin
Wisconsin 135
135 exit.
exit.
175.0
(3.0)
Jefferson/Waukesha
Jefferson/Waukesha county
county line.
line. Enter
Enter Waukesha
Waukesha County.
County. The
The
drainage in this rolling
rolling countryside
countryside is
is poor, and
and farm
farm fields
fields must
must
be ditched.
ditched. Numerous tamarack
tamarack swamps
swamps with red
red osier
osier dogwood
dogwood are
are
lingering evidence of the
the boreal
boreal climate
climate of
of the
the Pleistocene.
Pleistocene.
178.0
(4.0)
Wisconsin 67
67 exit
exit to
to Oconomowoc
Oconomowoc and
and Dousman.
Dousman. The interstate now
traverses
traverses outwash and proglacial lake sediments in an area once
occupied by the
the Green Bay
Bay lobe
lobe during the
the Woodfordian
Woodfordian ice
ice advance.
advance.
To
To the
the east, the
the view of the
the Interlobate
Interlobate Moraine
Moraine looming
looming above
above the
the
flat
flat outwash surface
surface is
is impressive.
impressive. A
A few
few overgrown kettles are
are
adjacent to
to the
the highway
highway on
on the
the south
south side.
side. To the north,
north, rising
rising
above the flat
flat outwash plain,
plain, an incongruous landform
landform resembles
resembles
the classic moulin kames
kames of
of the
the northern
northern Kettle
Kettle Moraine.
Moraine. This is
is
the artifically—created
artifically-created ski
ski hill
hill near
near Oconomowoc.
Oconomowoc.
182.0
182.0
(1.0)
(1.0)
An
An exit
exit on
on County
County CC
CC provides
provides aa side
side trip
trip to
to view
view the
the Kettle
Kettle
26
26
Mileages
Mileages
Interlobate Moraine
Moraine from
from the
the observation
observation tower
tower on
on Lapham
Lapham Peak.
Peak.
This
This tower
tower provides
provides an
an excellent
excellent overview
overview from
from the
the highest
highest
vantage
vantage point
point in
in the
the southern
southern Kettle
Kettle Interlobate
Interlobate Moraine.
Moraine. To
To
the
the west
west is
is Genesee
Genesee Flat.
Flat. To the east is
is the
the glacial
glacial spillway
spillway
described
described at
at mile
mile 184.
184. Several scenic,
scenic, glacial
glacial lakes
lakes are
are also
also
visible.
visible.
To reach Lapham Peak,
Peak, go south
south on County CC (Kettle
(Kettle Moraine Scenic
Scenic
Turn
left
(east)
onto
Drive)
about
1.8
miles
to
a
crossroad.
Drive) about 1.8 miles to a crossroad.
left (east) onto
Government
Government Hill
Hill Road.
Road. Continue about 0.7
0.7 mile to
to aa small
small park
that includes
includes the
the Lapham
Lapham Peak
Peak observation
observation tower.
tower. The
The tower
tower for
for
state station
station WHAD
WHAD is
is also
also located
located here.
here. A
A marker at
at 1233
1233 feet
feet
of elevation,
elevation, on a
a glacial erratic boulder in
in the
the park,
park, is
is dedicated
dedicated
to one of
of Wisconsin's earliest
earliest geologists
geologists and
and naturalists:
naturalists:
"Increase A.
A. Lapham,
Lapham, Eminent scientist
scientist and
and useful
useful citizen."
citizen."
The route
route ahead
ahead crosses
crosses a
a region
region of
of pitted (kettled)
(kettled) outwash
outwash
deposits, and
and many
many kettle
kettle lakes
lakes dot
dot the
the landscape.
landscape. Nagawicka
Nagawicka Lake,
Lake,
immediately
immediately north
north of
of the
the highway,
highway, is
is such
such aa lake.
lake. Other examples
examples
are
are Upper and Lower Nemahbin lakes,
lakes, which sandwich the interstate
west of
of here.
here. The ice blocks which formed
formed these lake
lake
about 1 mile west
basins were derived from
from the
the Green
Green Bay
Bay lobe
lobe along
along the
the western
western edge
edge
of the Interlobate
Interlobate Moraine.
Moraine.
183.0
183.0
(1. 0)
(1.0)
The interstate approaches the crest of the Interlobate
Interlobate Moraine.
Moraine.
A
small
ski
area
south
of
the
highway
utilizes
A small ski area south of the highway utilizes part
part of
of this
this slope.
slope.
From the crest of this ridge,
ridge, the radio tower and
and observation tower
tower
on Lapham
Lapham Peak are
are visible
visible south
south of
of the
the highway.
highway.
The Kettle Interlobate Moraine,
Moraine, which trends northeasterly across
across
Wisconsin for
for about 130 miles,
miles, from
from Walworth to
to Kewaunee
Kewaunee counties,
counties,
It is
is probable that the
is the
the premier glacial feature
is
feature in
in Wisconsin.
Wisconsin.
It
resistant Silurian
Silurian dolomite
dolomite influenced the
the position of the inter—
resistant
interlobate deposits
deposits in
in this
this area,
area, by retarding the spread of the Green
lobate
Bay lobe.
lobe.
Within this morainal complex,
complex, the country
country is
is rolling
rolling and
and rugged,
rugged,
This feature formed
with abundant knobs
knobs and
and kettles.
kettles.
formed during the
Woodfordian glacial advance by a
a juxtapositioning
juxtapositioning of
of the
the terminal
terminal
inoraines
of the
the Green
Green Bay
Bay and
and Lake
Lake Michigan
Michigan lobes. Between these
moraines of
walls, complex drainageways
drainageways developed,
developed, and meltwaters reworked
icy walls,
some
a
some of the morainal materials. The resultant deposits are a
Much of the
mixture of sand,
mixture
sand, gravel, boulders, and
and clayey
clayey till.
till.
material was
was derived from the Silurian dolomite,
coarser material
dolomite, but
igneous and
and metamorphic
metamorphic rock
rock types
types from
from far
far to
to the
the north
north are
are also
also
igneous
present.
184.0
184.0
(1.
0)
(1.0)
This highway
highway follows
an
Wisconsin 83
83 exit.
exit. This
follows low ground along an
abandoned drainage
drainage channel
channel which
which carried the
the last meltwater that
abandoned
drained southward
southward through
through this
this part
part of the
the Kettle
Kettle Interlobate
drained
Water drained
drained down
down this
this .25
mile wide
wide valley
valley until
until it
Moraine.
.25 mile
Moraine. Water
reached Wales,
Wales, about
about 33 miles
miles to
to the
the south,
south, where
where it
it cut
cut through
through the
the
reached
Gravel outwash
outwash terraces
terraces flank
flank
Interlobate
Interlobate Moraine
Moraine to
to flow west.
west. Gravel
this drainage,
drainage, and
and aa remnant
remnant of aa high terrace
terrace is
this
is visible on the
east
east side
side of this valley.
27
27
Mileages
185.0
(1.0)
(1.
0)
Pewaukee Lake
Lake lies
lies to
to the
the north.
north. The church at
at Holy
Holy Hill,
Hill, on
on aa kame
kame
perched high on the Interlobate
Moraine,
is
also
visible
to
the
north
Interlobate
is also visible to the north
on aa clear
clear day.
day. Pewaukee Lake occupies aa preglacial river
river valley
valley which
which
was scoured into the Upper Ordovician Maquoketa Shale.
This
Shale. This ancient
valley was blocked by morainal debris deposited along
along its
its eastern
eastern
margins by the Lake Michigan lobe
during
the
Woodfordian
ice
lobe
the
ice advance.
advance.
186.0
(2.0)
Ground moraine deposits in
in this
this area
area are
are thin.
thin. North of the highway
on the west edge of the Tumblebrook golf
golf course,
course, there
there is
is aa small
small
quarry in
Silurian
dolomite.
Glacial
striae
on
bedrock
in this
in Silurian dolomite.
area indicate that ice
ice movement was
was west—southwest.
west-southwest.
the road,
road, the
the names
names of a
South of the
a subdivision (Pebble
(Pebble Valley),
Valley), and
Hill), bear testimony to the character of the
aa farm (Stoney
(Stoney Hill),
the
morainal material.
material.
188.0
(3.0)
Exit County GG to
the highway
to Pewaukee.
Pewaukee. A drumlin field lies south of the
for the next several
several miles.
miles. These east—west
east-west trending drumlins are
composed of sandy clay till
till that contains abundant boulders.
boulders.
191.0
(1. 0)
(1.0)
Exit County
County F.
F. West of this intersection,
intersection, the
the route
route crossed
crossed the
the
Pewaukee River,
River, which
which is
is tributary
tributary to
to the
the Fox.
Fox. This valley is
is
paralleled by outwash terraces,
terraces, which are commercial
commercial sources
sources of
of sand
sand
and gravel
gravel in
in this
this area.
area.
192.0
(2.0)
Exit Wisconsin 164
164 to
to Sussex
Sussex and
and Waukesha.
Waukesha.
lins are ,north
north and
and south
south of
of the
the highway.
highway.
East-west trending drum-
Colonel Dunbar,
Dunbar, while visiting Waukesha in 1869, drank
drank from
from some
some of
of
the springs
the
springs which issue from the glacial drift,
drift, with high amounts
amounts of
of
dissolved calcium
calcium magnesium
magnesium bicarbonate.
bicarbonate. Upon deciding that the
local
local mineral waters had eliminated his "incurable
"incurable ailments,"
ailments," he
he
began to
to advertise
advertise his cure
cure nationwide,
nationwide, and
and Waukesha
Waukesha soon
soon became
became aa
fashionable health spa.
fashionable
spa. Although this fad
fad waned after about
about 30
30 years,
years,
bottled spring
water
is
still
a
Waukesha
product.
spring
is still a Waukesha product.
Waukesha
Waukesha is
is located
located on
on the
the Fox
Fox River.
River. Outwash terraces along
along this
this
river are important commercial sources for
for sand and
and gravel.
gravel. Since
the glacial drift is quite thin in this region,
the
region, Silurian dolomite
is
is extensively quarried along the valley of the Fox from
from the
the
Waukesha area
area northward to
to Sussex,
Sussex, Lannon
Lannon and
and Menomonee
Menomonee Falls.
Falls.
194.0
(3.0)
U.S. 18 (Blue
Exit U.S.
(Blue Mound Road)
Road) to Waukesha and WiscOnsin
Wisconsin State
Patrol Headquarters.
197.0
(2.0)
Exit Moorland
Moorland Road.
Road. The flat terrain here is
is poorly drained, clayclayground moraine.
moraine. Ditching and channelization were required
required for
for
rich ground
the extensive development
development of
of the
the land
land north
north of
of the
the highway.
highway.
The golf course to the south represents a more intelligent
intelligent land
land use.
use.
A few
few isolated patches of moraine,
moraine, and several east—west
east-west trending
trending
drumlins rise
rise above
above the
the generally
generally swampy
swampy ground.
ground.
The route
route ahead
descends aa prominent ridge,
The
ahead descends
ridge, which is part of the
28
Mileages
Mileages
Woodfordian
Woodfordian Lake
Lake Border
Border recessional
recessional moraine
moraine system.
system. Sunny
Sunny Slope
Slope
Road
Road traverses
traverses this
this ridge
ridge crest,
crest, which
which forms
forms the
the drainage
drainage divide
divide
between
between Lake
Lake Michigan
Michigan and
and the
the drainage
drainage basin
basin of
of the
the Fox
Fox River.
River.
The
The Fox
Fox flows
flows southward
southward parallel
parallel to
to the
the Woodfordian
Woodfordian moraines
moraines to
to
reach
reach the
the Illinois
Illinois River,
River, and
and ultimately
ultimately the
the Gulf
Gulf of
of Mexico
Mexico via
via
the Mississippi.
Mississippi.
the
199.0
199.0
(2.0)
(2.0)
Milwaukee/Waukesha
Milwaukee/Waukesha county
county line.
line. Enter Milwaukee
Milwaukee County.
County. Exit
Exit 1-894
1-894
(U.S.
45) south
south to Chicago and U.S.
(U.S. 45)
U.S. 45
45 north
north to
to Fond
Fond du
du Lac.
Lac. The
The
Milwaukee
Milwaukee County
County Zoo
Zoo is
is northwest
northwest of
of this
this intersection.
intersection.
202.0
202.0
(2.0)
(2.0)
Exit Wisconsin
Wisconsin 181
181 (84th
(84th Street).
Street). The
The Wisconsin State
State Fair
Fair Park
Park
Exit
grounds and an Olympic-size outdoor ice
ice rink
rink are
are southeast
southeast of
of this
this
Wisconsinan (Woodfordian)
junction.
junction. The interstate traverses
traverses Wisconsinan
(Woodfordian) ground
moraine
moraine and
and recessional
recessional moraines
moraines of
of the
the Lake
Lake Border
Border system.
system. The
The
highway
highway here
here is
is essentially
essentially parallel
parallel to
to the
the east-west
east-west direction
direction
of ice
ice movement,
movement, and
and consequently
consequently the
the morainic ridges
ridges trend
trend north—
northsouth. About 100
100 feet
feet of glacial
glacial deposits,
deposits, primarily
primarily aa boulder
boulder
south.
clay
clay till,
till, overlie
overlie Silurian
Silurian dolomite
dolomite in
in this
this area.
area.
204.0
(1.0)
(1.0)
U.S.
U.S. 41
41 exit
exit (north
(north and
and south).
south). Milwaukee County
County Stadium,
Stadium, home
home of
of
the Milwaukee Brewers and
also
the
site
of
the
Milwaukee
games
and also the site of the Milwaukee games of
of
the Green
Green Bay
Bay Packers,
Packers, is
is just
just west
west of
of this
this junction.
junction. The large
large
hill southwest of the stadium
is
a
Silurian
dolomite
stadium is a Silurian dolomite exposure
exposure on
on
the grounds of the
the
the U.S.
U.S. Veterans
Veterans Administration
Administration Hospital.
Hospital.
205.0
(1.0)
(1.0)
Route parallels the
the industrial
industrial complex
complex along
along the
the east-west
east-west trending
trending
Three
large,
glass
domes
in Mitchell Park
River valley.
valley.
large,
Menomonee River
are
to the
the south.
south. One contains a
a display of vegetation
are visible to
native to a desert environment,
another
features
environment, another features tropical
tropical plants,
plants,
and the
the last houses
houses local flora and is used for special flower shows.
shows.
206.0
Junction 1—94
1-94 with
with 1-43
1-43 (U.S.
(U.S. 141)
141) and
and 1—794.
1-794. The Milwaukee Harbor
is
to
the
southeast,
toward
the
highrise
Harbor Freeway bridge along
is to the southeast,
the
the lakeshore.
Three rivers merge at
at the
the Milwaukee
Milwaukee Harbor.
Harbor.
flows from
from the
the north
north and
and west,
west, the
the Milwaukee
Milwaukee
flows
north, and the
north,
the Kinnickinnic River originates
The Menomonee
Menomonee River
The
River comes
comes from the
the
to the west and south.
south.
Milwaukee grew from three settlements that were originally separated
Walker's Point,
by these rivers.
rivers. Walker's
Point, east of the Kinnickinnic River,
River,
is now
now dominated
dominated by
by the
the towering
towering clock
clock of
of the
the Allen
Allen Bradley Company.
Company.
is
The Milwaukee River flowed between Kilbourntown on the west and
The
Juneautown to
to the
the east.
east.
The high
high smokestack
smokestack to
to the
the east
east is
is part
part of the
the Jones
Jones Island
The
Here, sewage
sewage sludge
sludge is
is dried and
Metropolitan Sewage Plant.
Metropolitan
Plant. Here,
converted to Milorganite,
Milorganite, aa commercial
converted
commercial fertilizer.
fertilizer.
Jones Island,
Island, an
an artificially
artificially breached
breached peninsula,
peninsula, also contains
Jones
contains
tanker pier,
pier, cargo
cargo terminals
terminals and
and aa heavylift
heavylift wharf,
wharf, and is
aa tanker
is
Milwaukee's inner harbor
headquarters for the Port of Milwaukee. Milwaukee's
headquarters
29
was developed by an enlargement of the lower Kinnickinnic River,
was
River,
and it
it serves
serves as
as the
the service
service and
and wintering area for
and
for part of
U.S. Steel's iron ore carrier fleet.
u.s.
fleet.
END OF
OF LOG
END
Proceed through downtown Milwaukee to
Proceed
to the
the Pfister
Pfister Hotel.
Hotel.
30
30
,/
*
N
I
o0
NE
NE
QUARRY
QUARRY
A
A
,,-
\\ \I
/ '\
'\
rn
1!
200 FEET
FEET
Flynn's
SW
QUARRY
QUAR RY
QUARRY
--
—
\
/ , , / -:.- \I I " \
"'/ ,"- '\,
[J
I
"
-V,-.
\
\
/
.:::
N
~
A'
\
\
./
E
X P L A N AT I 0 N
EXPLANATION
METABASALT
METABASALT DIKE
DIKE
STRUCTURE RELATED
RELATED TO
TO
I• STRUCTURE
QUARRY OPERATION
OPERATION
QUARRY
J
o DEBRIS
DEBRIS PILE
PILE
D
[Tj
GRANITE
PORPHYRY
r,o "0)
GRANITE
PORPHYRY DIKE
DIKE
l'v I GRANITE
GRANITE AT
AT REDGRANITE
REDGRANITE
Figure
Figure 2.
2.
!
y'
1'
QUARRY WALL
OR STEEP
STEEP
QUARRY
WALL OR
SLOPE
SLOPE
Pace
Pace and
and compass
compass map
map of
of Flynn's
Flynn's Quarry
Quarry County
County Park,
Park, Waushara
Waushara County.
County.
32
32
Geologic
Geologic Stop
Stop Descriptions
Descriptions
. 11
Eugene
Eugene I.
I. Smith
Smlth
STOP 11 -- GRANITE
GRANITE AND
AND RELATED
RELATED INTRUSIONS
INTRUSIONS AT
AT FLYNN'S
FLYNN'S QUARRY
QUARRY COUNTY
COUNTY PARK
PARK
STOP
Location: All
All exposures
exposures at
at this
this stop
stop are
are reached
reached by
by an
an easy
easy walk
walk from
from the
the ParkParkLocation:
ing area
area (Fig.
(Fig. 2).
2).
ing
Description:
Description:
Granite
Granite
Fine—to
Fine-to medium—grained
medium-grained red
red (granophyric)
(granophyric) granite with micropegmatitic
micropegmatitic and
and
myrmeketic texture
texture is
is exposed in
in three
three quarries within the
the boundaries
boundaries of
of Flynn's
Flynn's
County Park
Park (Fig.
(Fig. 2).
2). Quartz and
and alkali
alkali feldspar
feldspar compose
compose 90
90 to
to 98
98 perperQuarry County
cent
cent of
of the
the rock,
rock, with biotite
biotite (partially
(partially or
or wholly altered
altered to
to chlorite),
chlorite), sphene,
sphene,
muscovite and
and zircon
zircon as
as subordinate
subordinate minerals.
minerals. The granite for
for the
the
hornblende, muscovite
most part
part is
is texturally
texturally homogeneous.
homogeneous. Locally
Locally however,
however, grain
grain alignments
alignments and
and fine—
fineThe mineralogy and texture of the granite
grained bands (dikes?)
(dikes?) are
are observed.
observed.
(especially
the intergrowths
intergrowths of
of quartz
quartz and
and alkali
alkali feldspar)
feldspar) suggest
suggest that
that it
(especially the
it is
is a
a
shallow
intrusion.
shallow intrusion.
Granite Porphyry Dike
Dike
In
northeast quarry,
quarry, the
the granite
granite is
is cut
cut by
by aa 200
200 m wide
wide east
east trending
In the
the northeast
granite porphyry dike
dike (strike
(strike east—west,
east-west, dip
dip 75°
75° to
to the
the south).
south). The dike rock
rock
is
characterized by
by large
large (5
mm) alkali
alkali feldspar
feldspar phenocrysts
phenocrysts set
set in
in aa fine—
is characterized
(5 mm)
fineof quartz,
quartz, biotite
biotite and
and chlorite.
chlorite. The finely disseminated chlorite
grained matrix of
gives the matrix of the
the dike rock a
a green color,
color, thus
thus making it easily distinguishable from
from the
the red
red granite.
granite. The contact between granite and dike rock is
is
clearly visible
visible on
on aa ledge
ledge on
on the
the north
north wall
wall of
of the
the northeast
northeast quarry
quarry (Fig.
(Fig. 3).
3).
In
detail, the
the contact
contact bends
bends in
in and
and out,
out, suggesting
suggesting some
some assimilation
assimilation of
granite
In detail,
of granite
during intrusion.
intrusion. Fragments (xenoliths)
(xenoliths) of
of granite are found
found within the
the dike
near the
the contact;
contact; also
also feldspar
feldspar phenocrysts
phenocrysts are
are concentrated
concentrated and
and weakly
weakly aligned
aligned
near
in
the granite mornhvrv
porphyry dike at
at the
the contact.
contact.
in the
Figure 3.
Figure
View of
of the
the contact
contact between
between the
the granite
granite porphyry
porphyry dike
dike and
and granite
granite
View
Note
in Flynn's
Flynn's Quarry
Quarry County
County Park (dashed
in
(dashed line traces
traces contact).
contact).
that the
the feldspar
feldspar phenocrysts
phenocrysts are
are concentrated
concentrated and
and weakly
weakly aligned
aligned
that
in the
the dike
dike rock near the
in
the contact.
contact.
of Science,
Science, University
University of
of Wisconsin-Parks
Wisconsin—Parkside,
lDivision
ide , Kenosha,
Kenosha, Wisconsin
Wisconsin 53141.
53141.
Division of
33
33
Chemically, the
the dike
dike is
is aa less
less differentiated
differentiated phase
phase of
of the
granite. It
It is
Chemically,
the granite.
lower in SiO , and K
K20
and higher
higher in
in Al
A1203,
Fe20
and CaO when
when compared to
lower
0 and
0 , FeO + Fe
0 and
2
3
uarry granite
1, an~lyses
analyses 18
18 and
and 31).
3).
In terms
terms of trace
the Flynn's auarry
g~anite (Table
(Table 1,
In
elements the
the dike
dike is
is higher
higher in
in Ba,
Ba, and
and has
has aa lower
lower Rb/Sr
Rb/Sr ratio than the
granite.
elements
the granite.
,
Metabasalt Dike
Dike
On the
the north
north wall
wall of
of the
the main
main quarry,
quarry, the
the granite
granite is
cut by a
m wide)
wide)
On
is cut
a thin (2
(2 m
0
metabasalt dike striking
striking N.
N. 80
80 E.
E. and
and dipping
dipping 700
70 to
to the south (Fig.
(Fig. 2).
2).
The dike
rock is
is fine
fine grained
grained and
and has
has aa distinctive
distinctive green color
color on both weathered and fresh
~ock
fresh
surfaces.
In
thin
section,
the
metabasalt
displays
intergranular
texture
with
In thin section, the metabasalt displays intcrgranular texture with
laths of
of plagioclase enclosing mats of
laths
of epidote,
epidote, clinozoisite
clinozoisite and
and iron
iron oxide.
oxide.
The
contact
between
the
metabasalt
and
granite
is
clearly
observed
on
a
contact between the metabasalt and granite is
observed
a ledge just
above
Here lenses
lenses of
of granite
granite are
above water level
level (Fig.
(Fig. 4).
4). Here
are completely enclosed by
stringers of metabasalt. Except for these lenses,
no
granite fragments
lenses,
fragments were
noticed within dike rock.
These
contact
relationships
suggest
that
rock.
that the
the meta—
metabasalt intruded
primarily
by
the
dilation
of
country
rock.
intruded primarily by the dilation of country rock.
Comparison of
of Flynn's
Flynn's Quarry
Quarry Granite
Granite to
to Granite
Granite in
in Nearby
Nearby Areas:
Areas:
Redgranite to
to Pine Bluff—
Bluff- Granites and Dikes
Granites similar in
Granites
in mineralogy and
and texture
texture to that
that at
at Flynn's
Flynn's Quarry are
exposed in discontinuous
discontinuous outcrops
Redgranite to Pine Bluff
exposed
outcrops from
from the
the city of
of Redgranite
(Fig.
(Fig. 5).
5). Dikes of
of metabasalt trending east—west
east-west and
and approximately
approximately N.
N. 45E.
45E. cut
cut
the
One of the
most easily visited of
the granite in
in many
many localities.
localities.
One
the most
of these dikes
forms
distinct ridge
ridge jutting into the
forms aa distinct
the quarry lake
lake north of S.T.H.
S.T.H. 22 in
downtown Redgranite
Redgranite (just
(just north
north of
of Griffs'
Griffs' Cafe).
Cafe). A
A coarse—grained
coarse-grained diorite
dike cuts granite in
in a small
small quarry in
in the
the N
N 1/2,
1/2, Sec.
Sec. 27,
27, T.18 N.
N. R.
R. 11
11 E.
E.
(Fig.
5). The
The dike
dike is about 5 m
(Fig. 5).
m thick
thick and
and trends
trends N.
N. 40
40 E.
E. (dip vertical).
In
thin section,
section, flow—aligned
flow-aligned plagioclase
plagioclase laths
laths surround
surround clots
clots of
of chlorite
chlorite and
and epidote.
epidote.
Montello Granite
Granite
Another granite similar in
in lithology to
to that
that at
at Flynn's Quarry and
and at
at Red
Red
Granite is located in
the
city
of
Montello
(Buckley,
1898).
in the city of Montello (Buckley, 1898). There is
is also
also an
an
exposure to the
the east of Montello in
in the
the SE
SE 1/4,
1/4, Sec.
Sec. 9,
9, T.
T. 15
15 N.,
N., R.
R. 10
10 E.
E.
This granite
granite was
was extensively
extensively quarried
quarried from
from 1880
1880 to
to 1976.
1976. President Grant's
sarcophagus in
in New York City is
is carved
carved from
from Montello
Montello Granite.
Granite. The rock in
in the
the
Montello quarry is
is a
a red granite composed of
of intergrown
intergrown quartz and
and alkali
alkali feldfeldspar crystals (myrmeketic
(myrmeketic and
and micropegmatitic textures
textures are common)
common) with chlorite,
chlorite,
biotite,
biotite, and
and euhedral
euhedral zircon
zircon as
as accessory
accessory minerals.
minerals. Attempts to
to date this
this rock
rock
by the
the fission—track
fission-track technique
technique failed because an
an insufficient
insufficient number of
of zircon
zircon
grains were separated
separated and
and most
most of
of the
the separated
separated zircons
zircons were
were metamict.
metamict. The
Montello granite is
is cut by thin
thin metabasalt dikes (plagioclase
(plagioclase and
and sausserite
sausserite as
as
dominant minerals)
Quarry
minerals) which
which trend
trend northeast,
northeast, north—south
north-south and
and northwest.
northwest.
faces
faces at Montello are
are commonly
commonly bounded
bounded by
by these
these dikes.
dikes. The metabasalt
metabasalt dikes
dikes
are closely sheared at
at their
their margins;
margins; several
several dikes
dikes are
are sheared
sheared throughout.
throughout. The
granite commonly shows
shows aa dark red
red bake zone
zone extending 22 to
to 5
5 cm
em inward
inward from
from the
the
intrusive contacts,
contacts, also small
more common in granite near
small grains
grains of
of pyrite are more
metabasalt
metabasalt than
than farther
farther away
away from
from the
the granite—dike
granite-dike contacts.
contacts.
34
34
Figure
Figure 4A.
4A.
View of a
a thin metabasalt
metabasalt dike that
that
The
dike
in
this
view
County
Park.
County Park.
in this view
dips about
southern
southern contact
contact (left)
(left) dips
about
Granite (G)
to
the
north of
line).
(G)
in the dike rock
rock (D).
(D).
Figure
4B.
Figure 4B.
Close—up of the contact between the
Close-up
the metabasalt dike
dike and
and granite.
granite.
Basalt intruded granite along
Basalt
along closely
closely spaced
spaced joints.
joints.
35
cuts
cuts granite in Flynn's Quarry
is
is 22 meters
mete~s thick.
thick. The
10° to the north
north (dashed
the dike appears
appears as
as a window
Lohrville
Lohrville
Quarries
Redg ranj.t(f~~---/'
.c-"~edgranite Quarry
—2'FIynns
Spring Lake,
Lake"",
/_Jf\.
Flynn's Quarry (STOP
(STOP I)
I)
Spring
Quarri es
Quarries
I"
WAUSHARA COUNT
COUNTY
WAUSHARA
-MARQUETTE COUI
COU
.YY
;,.' -
Quarry
Quarry with
with Diorite Dike
Dike
—
T;--
GREEN
GREEN LAKE
LAKE COUNTY
COUNTY
00 Berlin
Gran ite
Berlin
Pine
Pine Bluff Granite
I
I
I
o
I
I
"--1
~
Granite
Montello Granite
Buffalo
Lake
Figure 5.
5.
3:iiii~
2 3 4 5 Miles
0
.Oiii32• 3iE!
Mil es
SCALE
SCALE
I
I
Princeton
EXPLANATION
...
C.J
Granite
Exposures
~
Quarry
00
City
Field Trip
Trip
~ Field
Route
Route
Detailed route
route map
map from
from Redgranite
Redgranite to
to Montello
Montello showing
showing granite
granite
Detailed
exposures and
and locations
locations of important quarries.
exposures
quarries.
36
36
_____________ _________
Chemical Comparisons:
The granite at
at Redgranite (and
(and presumably Flynn's Quarry)
Quarry) is
is similar in
in
chemistry, mineralogy and age to that
chemistry,
that at Montello,
Montello, except for noticably higher
higher
amounts of
of Cu and Cr in
amounts
in the
the Montello
Montello Granite,
Granite, (Table
(Table 1,
1, analyses
analyses 14
14 and
and 18).
18).
These similarities indicate that the granites are comagmatic and
and that
that they
they
formed during the same intrusive
formed
intrusive event.
event.
Studies of cuttings from
from deep
deep wells
wells
show that
that granite lithologically similar to
to that
that exposed at
at Redgranite and
and
Montello occurs in the basement over a
a large area of south—central
south-central Wisconsin.
Wisconsin.
These rocks
rocks probably
probably form
form aa large
large late—Penokean
late-Penokean or
or post—Penokean
post-Penokean (1765
(1765 m.y.
m.y. old)
old)
composite batholith which is exposed only in
in the
the Redgranite area
area and
and at
at Montello
(Smith, 1978c).
(Smith,
The similarity of the
the granites at Montello and
and Redgranite was noted
noted long
long
ago by Weidman (1904)
who
labelled
these
rocks
the
Waushara
Granite.
(1904)
labelled these rocks the Waushara Granite. Emmons
(1940) also
also suggested the presence of aa large
(1940)
large batholith
batholith in
in central
central Wisconsin.
Wisconsin.
However,
he
did
not
distinguish
between
the
older
Penokean
aged
granites
However,
the
aged granites in
in
central Wisconsin (Wausau area)
area) and
and the
younger granites
granites in south—central
central
the younger
south-central
Wisconsin.
-
44
--
3
--
-
--
-
--
-
-
2
-- -
0.
Co
:::J
0
(I
o
I
I
I
I
I
I
o0200500400500600
200 300 400 500 600
0
10
Zr
20
-
-
-
•
~I
I
I
3040
30 40 50
50
I
0
50
I
I
10015020
100
150 20 3040
30 40
Cu
Cr
I
--I
0)
50
Pb
I
I
100150200250
100
150 200 25 o
Zn
Zn
4—
4
3 -3
2
0.
Co
:::J
0
o1
~I
I
0
o
000
1000
500
Ba
Ba
ao
2.0
I
I
50
50
00
100
I
I
150
150 00
200
Sr
La
tOO 150
50 200
100
200
Rb
10
10
30
50
I
I
I
70
70
90
90
ItO
110
V
Y
(ppm)
Figure
6
6.
chemical groups
groups (from
Some elemental
concentrations for
for the four
four chemical
(from
elemental concentrations
for
Smith, l978a).
1978a). Bars indicate
indicate the
the range
range of
of values
values for each
each chemical
chemi~al
Smith,
group.
Dot indicates that
data point is
is based
based on
on one
one analysis.
analysls.
that the
the data
Dot
group.
37
Relationship of Granites to
to Rhyolite:
Rhyolite:
The Redgranite
Redgranite and
and Montello
Montello Granites
Granites are
are similar
similar in
in major
major 8nd
cnd mino~
minor element
element
The
chemistry and
and age
age to
to the
the rhyolites
rhyolites exposed
exposed to
to the
the south
south (stop
for example)
example)
chemistry
(stop 22 for
(see table
analyses 4-29;
4—29; and
and Fig.
Fig. 6;
6; and Smith,
(see
table 11 , analyses
Smith, 1978c by Van
Van Schmus,
Schmus, 1978.
1978.
These similarities
similarities strongly
strongly suggest
suggest that
that the
the granites
granites and
and rhyolites
rhyolites are
are comagThese
comag—
matic.
In other
other words,
words, the
the granites
granites may
may represent
represent the
the magma
magma chambers
chambers from
from
matico
In
which the
which
the rhyolite ash—flow
ash-flow tuffs
tuffs were erupted.
erupted. Later,
its
Later, granite intruded its
own volcanic
volcanic cover engulfing much of
9wn
of the
the rhyolite.
rhyolite. Surviving
Surviving rhyolite exists
as roof
roof pendants within
as
within the
the granite.
granite.
,
38
38
Table 1.
1.
NEW CHEMICAL ANALYSES FOR CENTRAL WISCONSIN INLIERS AND IGNEOUS ROCKS
ROCKS IN THE BARABOO
BARA~OO AREA
AREA
11
2
2
3
3
4
4
5
5
6
6
w
CA,
°t.O BB
Ba
Ba
Co
Co
Cr
Cr
Cu
La
La
Mo
Ni
Ni
V
Y
Y
Zr
Pb
Pb
Rb
Sr
Zn
Zn
Sc
Sc
20
20
1300
1300
33
32
32
30
30
49
10
10
12
12
77
32
32
320
28
165
165
210
210
55
70.61
0.37
14.29
0.92
2.03
0.34
1.61
4.45
3.78
0.92
0.04
0.08
99.55
70.26
0.30
14.10
0.86
2.66
0.10
1.02
1.48
4.29
3.69
1.32
1.
32
0.04
0.17
100.29
71.79
71. 79
0.28
14.46
1.40
0.86
0.07
0.30
1.34
3.48
4.63
1.25
1.
25
0.09
0.08
100.03
24
1350
33
15
20
55
10
10
10
33
38
440
22
22
154
212
190
55
25
1200
33
25
50
31
31
10
10
66
15
15
320
22
22
120
324
110
55
28
690
33
55
120
35
10
10
66
30
200
40
40
152
105
130
0.11
O.ll
8
8
99
10
GROUP 22
GROUP 11
69.28
Si02
0.42
Ti02
TiO2
A1203 13.90
Fe203
1.37
2.89
FeO
0.14
MnO
0.90
MgO
CaO
1.68
Na20
4.17
K20
4.33
H20+
0.92
0.07
H20H20—
0.18
P205
P205
TOTAL 100.25
7
7
71.81
71. 81
0.26
14.29
1.57
1.
57
0.90
0.06
0.20
1.15
4.14
4.54
1.09
0.05
0.09
100.15
33
650
33
10
55
40
10
10
88
22
230
30
125
97
70
72.95
0.25
13.77
13.77
1.69
0.72
0.06
0.26
0.91
3.88
4.46
0.73
0.04
0.04
99.76
71.11
71.11
0.28
14.68
1.67
0.84
0.06
0.26
1.11
4.00
4.35
1.21
1.
21
0.06
0.09
99.72
20
590
33
11
60
35
10
10
99
28
210
45
137
97
145
20
650
33
10
45
45
10
10
10
30
240
30
134
137
105
73.07
0.28
14.65
1.60
0.69
0.06
0.06
0.13
0.94
3.78
4.21
0.78
0.06
0.05
100.30
28
690
33
11
II
55
47
10
10
6
30
210
40
138
95
105
72.85
72.85
0.27
0.27
13.88
1.13
1.09
1.
09
0.05
0.05
0.27
0.27
1.09
1.09
3.58
3.58
4.53
0.96
0.05
0.05
0.10
99.85
71.85
71. 85
0.29
14.32
14.32
0.68
0.68
1.82
1.
82
0.09
0.09
0.26
0.26
1.25
1.
25
3.68
3.68
4.52
4.52
0.78
0.78
0.08
0.08
99.70
99.70
22
630
33
10
55
40
10
10
88
22
230
35
35
130
130
130
130
70
70
20
20
720
33
12
12
45
42
10
10
10
10
55
30
200
200
45
116
116
150
150
115
115
Table 1.
1. (Continued)
(Continued)
11
11
12
12
13
13
14
14
15
15
16
16
17
17
GROUP 22 Continued)
GROUP
(Continued)
Si02
Si02
Ti02
A1203
A12O3
Fe203
FeO
MnO
MgO
CaO
GaO
Na20
K20
H20+
H20P205
71.22
0.24
0.24
14.15
14.15
1.53
0.70
0.12
0.12
0.15
0.15
2.03
2.03
3.14
4.66
1.94
0.05
0.07
TOTAL 100.00
71.64
71.64
0.28
14.36
14.36
1.84
1.84
0.65
0.07
0.28
1.37
1.
37
4.07
3.74
1.50
0.09
0.10
99.99
18
18
19
19
20
20
GROUP 33
72.27
72 .27
0.30
13.83
13.83
1.51
1. 51
1.08
1.08
0.08
0.24
1.61
1. 61
3.87
3.72
1.51
1. 51
0.07
0.09
72.33
72 .33
0.28
13.62
1.94
1.94
0.68
0.07
0.29
1.27
4.70
3.73
1.16
0.05
0.10
75.83
0.21
11.92
11.
92
1.08
0.98
0.07
0.06
0.53
3.43
5.45
0.54
0.01
0.01
75.09
0.21
12.33
12.33
1.08
1.12
0.08
0.04
0.39
3.76
5.58
0.49
0.00
0.01
100.18
100.22
100.12
100.18
25
25
20
73.73
0.29
12.09
12.09
1.83
1.83
1.34
0.11
0.04
0.36
3.50
6.03
0.36
0.01
0.01
0.00
99.69
76.14
0.24
11.79
11. 79
1.10
1.10
0.88
0.02
0.09
0.45
3.16
5.65
0.58
0.01
0.01
0.01
0.01
100.12
75.30
0.19
0.19
12.04
12.04
1.04
1.04
1.04
1. 04
0.06
0.06
0.04
0.04
0.33
0.33
4.65
4.65
4.63
4.63
0.33
0.33
0.03
0.03
0.00
0.00
99.68
99.68
75.60
75.60
0.17
0.17
12.59
12.59
0.99
0.99
0.71
0.71
0.03
0.03
0.04
0.04
0.13
0.13
4.46
4.46
4.95
4.95
0.47
0.47
0.02
0.02
0.00
0.00
100.16
100.16
A
o
B
B
Ba
Co
Co
Cr
Cu
La
La
Mo
Ni
Ni
V
yy
Zr
Pb
Pb
Rb
Rb
Sr
Zn
Zn
Sc
Sc
29
29
730
33
11
11
55
55
45
10
10
10
10
77
27
27
190
50
50
155
155
126
120
26
26
26
26
20
20
630
3
3
9
9
55
55
35
35
10
10
10
12
12
28
200
40
116
126
126
115
750
33
88
72
37
37
10
10
10
10
12
12
22
22
210
40
102
102
135
135
85
-
-
-
650
3
3
77
50
37
37
10
10
10
10
10
27
270
35
75
106
106
120
120
-
440
3
3
38
23
78
10
10
10
10
5
5
70
420
22
190
190
25
55
55
33
410
3
3
23
22
90
10
10
10
5
5
71
590
23
152
152
31
125
125
33
20
20
390
33
27
26
120
10
10
55
85
550
22
152
11
115
33
20
20
390
33
88
9
95
10
10
10
55
65
590
28
202
21
65
3
22
22
22
22
115
115
545
545
3
13
13
22
22
72
10
10
10
10
55
49
450
19
19
117
117
55
105
105
33
33
16
16
25
25
65
10
10
10
10
55
49
480
480
28
120
120
28
28
95
95
33
Table
Table 1.
1. (Continued)
(Continued)
21
21
22
22
23
25
25
24
24
26
26
27
27
28
28
MARCELLON
Si02
Si02
Ti02
Ti02
A1203
A1203
Fe203
Fe203
FeO
FeO
MnO
MnO
MgO
MgO
CaO
CaO
Na20
Na20
K20
K20
H20+
H20+
H20H20P205
P205
TOTAL
TOTAL
B
B
oJ:>. Ba
,.... Co
Cr
Cr
Cu
Cu
La
La
Mo
Mo
Ni
Ni
Co
V
V
Y
Y
Zr
Zr
Pb
Pb
Rb
Rb
Sr
Sr
Zn
Zn
Sc
Sc
75.68
75.68
0.12
0.12
12.46
12.46
0.68
0.68
1.09
1.09
0.13
0.13
0.12
0.12
0.36
0.36
3.66
3.66
5.00
5.00
0.57
0.57
0.04
0.04
0.07
0.07
99.98
99.98
78.25
78.25
0.11
0.11
11.05
11.05
0.95
0.95
0.84
0.84
0.07
0.07
0.16
0.16
0.29
0.29
3.66
3.66
3.72
3.72
0.70
0.70
0.09
0.09
0.09
99.98
75.55
75.55
0.14
0.14
12.21
12.21
0.42
0.42
1.71
1.71
0.17
0.17
0.29
0.29
0.45
0.45
2.82
2.82
5.16
0.85
0.04
0.06
99.87
76.63
0.12
11.38
11.38
0.97
0.97
1.13
0.12
0.12
0.13
0.62
3.16
4.66
0.59
0.01
0.06
99.58
40
40
240
240
33
54
54
95
95
47
47
10
10
55
55
50
50
200
200
22
22
131
131
72
72
100
100
55
25
25
160
160
33
44
44
115
115
35
35
10
10
11
11
55
42
42
180
180
19
19
108
108
61
61
130
130
55
20
20
180
33
62
62
160
160
50
50
10
10
55
55
52
52
200
180
180
165
165
61
61
105
105
55
35
35
240
33
41
80
45
45
10
10
55
55
50
50
190
190
14
14
130
130
46
110
55
,
29
29
BARABOO
BARABOO
71.99
71. 99
0.26
0.26
13.57
1.93
1.
93
0.88
0.11
0.37
1.10
4.34
4.91
1.20
1.
20
0.08
0.03
100.77
.
30
970
5
5
15
15
40
90
10
10
55
88
60
150
22
102
95
95
102
102
77
71.80
0.32
13.74
1.30
1.72
0.11
0.58
0.85
4.43
4.49
0.60
0.04
0.13
100.11
100.11
20
1050
3
3
58
105
52
10
55
55
35
220
18
110
176
135
135
77
73.77
0.14
0.14
12.35
1.01
1.81
1.
81
0.13
0.13
0.39
0.94
3.26
4.92
1.25
0.04
0.07
100.08
100.08
22
22
410
3
3
58
58
110
42
10
55
55
38
160
19
108
82
82
110
55
73.83
73.83
0.16
0.16
13.33
13.33
0.96
0.96
1.21
1. 21
0.07
0.07
0.31
0.31
0.43
0.43
2.51
2.51
5.28
5.28
1.43
1.43
0.05
0.05
0.08
0.08
99.65
99.65
27
1100
1100
3
3
25
25
42
42
49
49
10
10
10
33
31
240
55
205
110
110
35
35
55
72.76
72.76
0.22
0.22
13.34
13.34
1.77
1.77
0.72
0.72
0.12
0.12
0.18
0.18
0.45
0.45
4.39
4.39
5.25
5.25
0.77
0.77
0.08
0.08
0.01
0.01
100.06
100.06
35
35
950
950
5
5
22
22
45
45
80
80
10
10
55
55
33
33
140
140
25
25
115
115
62
62
115
115
77
I
Table 1.
1. (Continued)
Table
(Continued)
30
31
32
33
34
35
35
36
36
37
37
DIKES
Si02
Ti02
A1203
Fe203
FeO
MnO
MgO
CaO
CaO
Na20
1(20
K20
H20÷
H20+
H20—
H20P205
P205
TOTAL
>l:>
t'V
B
B
Ba
Ba
Co
Co
Cr
Cr
Cu
La
La
Mo
Mo
Ni
Ni
V
V
Y
Zr
Zr
Pb
Pb
Rb
Sr
Zn
Sc
63.92
0.94
0.94
15.65
15.65
1.92
1.
92
4.38
0.20
1.40
1.40
1.58
1.58
4.71
4.71
3.34
3.34
1.51
0.11
0.11
0.31
0.31
99.97
99.97
72.10
0.30
12.74
1.06
2.21
0.12
0.09
1.08
3.12
6.12
0.73
0.03
0.04
99.74
20
20
20
1050
1050
1170
3
3
3
3
12
12
65
65
26
16
16
88
88
10
10
10
10
5
5
63
590
19
180
56
110
33
40
10
10
10
10
15
15
25
25
200
30
30
113
218
218
75
75
-
60.59
0.93
16.47
1.61
1.61
4.50
0.18
1.77
3.86
4.27
3.27
1.50
0.11
0.48
99.54
50
1200
4
4
16
70
68
10
10
6
6
92
28
28
220
25
25
105
514
180
20
48.94
0.99
17.84
2.21
6.56
0.19
6.57
9.59
3.25
1.11
2.97
0.12
0.31
100.29
25
660
24
42
50
10
10
10
24
24
240
11
11
75
75
28
28
38
642
180
27
49.47
0.94
14.77
1.46
7.42
0.19
7.05
6.54
4.59
1.09
5.57
0.18
0.36
99.63
52.02
1.27
15.84
2.66
7.72
0.21
4.78
7.87
3.23
1.66
1.96
0.10
0.34
99.66
15
680
20
155
77
21
10
19
240
14
86
15
15
55
55
270
170
25
25
33
950
20
27
27
75
75
29
10
10
270
31
31
180
180
20
20
154
154
419
190
24
24
60.72
0.99
15.72
1.13
5.86
0.19·
0.19
1.89
1.
89
3,94
3.94
3.90
3.31
1.43
0.10
0.46
99.64
56.21
1.33
1.33
13.20
13.20
1.95
1.
95
6.66
6.66
0.14
0.14
5.10
6.01
3.09
2.56
2.34
0.14
0.98
99.71
22
22
1250
77
20
32
32
33
33
10
16
55
55
32
32
240
22
22
155
155
420
220
16
16
70
70
1100
37
150
80
95
95
10
10
51
51
260
260
45
620
21
21
75
75
625
160
160
23
23
I
Table 1.
1. (Continued)
(Continued)
Si02
Si02
Ti02
Ti02
A1203
A1203
Fe203
Fe203
FeO
FeO
MnO
MnO
MgO
MgO
CaO
Na20
Na20
K20
K20
H20+
H20+
H20H20P205
P205
TOTAL
TOTAL
..,.
w
B
B
Ba
Ba
Co
Co
Cr
Cr
Cu
Cu
La
La
Mo
Mo
Ni
Ni
V
V
yY
Zr
Zr
Pb
Pb
Rb
Rb
Sr
Sr
Zn
Zn
Sc
Sc
38
38
39
39
40
40
69.76
69.76
0.37
0.37
13.77
13.77
0.76
0.76
2.25
2.25
68.44
68.44
0.50
0.50
14.20
14.20
1.46
1.46
2.99
2.99
0.17
0.17
0.62
0.62
2.02
4.78
4.78
3.06
1.11
1.11
0.04
0.13
99.52
70.22
70.22
0.35
14.26
14.26
0.94
2.47
2.47
0.19
0.34
0.34
1.30
4.48
3.76
1.07
0.06
0.09
99.53
17
17
990
990
33
28
28
135
135
40
40
20
20
10
10
55
22
22
280
280
25
25
105
105
205
205
97
97
20
20
1250
1250
55
15
15
110
110
29
29
20
20
55
22
22
29
29
260
260
20
20
1400
55
25
25
90
40
20
55
55
30
270
-----
-----
---
10
55
0.13
0.43
0.43
2.30
2.30
. 3.95
3.95
3.55
3.55
2.12
2.12
0.03
0.03
0.11
0.11
99.53
99.53
-----
-----
72
72
420
84
84
275
275
41
41
42
43
43
71.20
71.20
0.47
0.47
14.90
1.72
1.60
67.60
67.60
0.44
0.44
15.10
1.75
1.
75
2.24
2.24
76.17
76.17
0.17
0.17
12.05
0.96
0.96
1.00
0.03
0.11
0.26
3.76
4.27
0.63
0.07
0.06
99.53
-----
---
0.72
0.71
0.71
1.70
1.
70
5.98
0.70
0.40
1.10
2.10
1.95
1.95
4.95
1.60
0.90
100.38
100.62
-----
18
550
33
45
410
33
20
10
10
40
20
220
220
10
190
190
26
110
66
---
25
25
450
25
17
370
35
20
17
35
20
220
40
40
180
79
205
66
16
16
165
165
33
45
45
155
55
20
10
17
26
340
16
95
26
120
55
Table 1.
1.
Number
Sample
Number
Explanation
Description.
Description
1.
1.
179
Coarse-grained rhyolite dike on Observatory
Hill.
2.
2.
180
Contact zone of coarse-grained rhyolite dike
on Observatory Hill.
on
Hill.
3.
3.
183
Baxter Hollow
Hollow Granite.
Granite.
4.
89
5.
5.
102
Marquette rhyolite
rhyolite (unit
(unit G).
G).
6.
6.
106
Marquette rhyolite
rhyolite (unit
(unit G).
G).
7.
7.
101
Marquette rhyolite
rhyolite (unit
(unit F).
F).
8.
8.
100
Marquette rhyolite
rhyolite (unit
(unit E).
E).
9.
9.
103
Marquette rhyolite
rhyolite (unit
(unit D).
D).
10.
104
Marquette rhyolite
rhyolite (unit
(unit D,
D, massive
massive phase).
phase).
11.
91
Marquette rhyolite
rhyolite (unit
(unit C).
C).
12.
92
Marquette rhyolite
rhyolite (unit
(unit B).
B).
13.
98
Marquette rhyolite
rhyolite (unit
(unit B).
B).
14.
99
99
Marquette rhyolite
rhyolite (unit
(unit B).
B).
15.
15.
107
Montello Granite.
Granite.
16.
16.
108
Observatory Hill
Hill rhyolite.
rhyolite.
17.
17.
109
Endeavor rhyolite.
rhyolite.
18.
110
Granite at Redgranite collected
collected in
in Flynn's
Flynn's
Quarry.
19.
19.
112
Berlin rhyolite.
rhyolite.
Marquette rhyolite (unit
(unit C)
G) from
from Noble's
Quarry. Samples 4-14 are
are keyed
keyed to
to figure
figure 45.
45.
44
Table
Table 1.
1.
Explanation
Explanation (Continued)
(Continued)
20.
20.
114
114
Utley
Utley rhyolite.
rhyolite.
21.
21.
173
173
Marcellon
Marcellon rhyolite
rhyolite (unit
(unit A).
A). Sample
Sample
numbers
21-27
are
keyed
to
figure
numbers 21-27 are keyed to figure 33.
33.
22.
22.
176
176
Marcellon
Marcellon rhyolite
rhyolite (unit
(unit A).
A).
23.
23.
174
174
Marcellon
Marcellon rhyolite
rhyolite (unit
(unit B).
B).
24.
24.
161
161
Marcellon rhyolite
rhyolite (unit
(unit B).
B).
25.
25.
145
Marcellon rhyolite
rhyolite (unit
(unit C).
C).
26.
26.
175
175
Marcellon
Marcellon rhyolite
rhyolite (unit
(unit C).
C).
27.
27.
178
178
Marcellon rhyolite
rhyolite (unit
(unit D).
D).
28.
28.
182
182
Caledonia Church rhyolite
rhyolite (south
(south limb
limb
of the
the Baraboo Syncline).
Syncline).
29.
29.
147
Baraboo rhyolite
from the
the NE
NE ~,
, sec. 23,
rhyolite from
T. 12
T.
12 N.,
N., R.
R. 7 E.
30.
30.
105
Marquette andesite
andesite dike
dike (figure
(figure 45).
45).
31.
31.
111
111
Granite porphyry dike from
from Flynn's Quarry
County Park.
Park.
32.
32.
148
Marcellon andesite
andesite dike
dike (figure
(figure 33).
33).
33.
33.
177
Marcellon basalt dike
dike (figure
(figure 33).
33).
34.
34.
153
Netabasalt dike
Metabasalt
dike at Montello (collected
(collected from
from
23).
quarry just north
north of
of S.H.
S.H. 23).
35.
35.
154
154
Metabasalt dike at Redgranite (from
(from quarry
city of Redgranite).
36.
36.
155
dike from
granite quarry near
Diorite dike
from granite
11 E.).
E.).
27, T.
T. 18 N., R.
Spring Green
Green (NE
(NE ~,, sec. 27,
Spring
R. 11
37.
37.
184
Denzer diorite
45
45
Pable 1.
1.
Table
Explanation (Continued)
(Continued)
Explanation
38.
38.
192
192
Dacite dike
dike at
at Marquette
Marquette (figure
Dacite
(figure 45).
45) .
39.
39.
190
190
Dacite dike
dike at
at Marquette
Marquette (figure
Dacite
(figure 45).
45) .
40.
40.
191
191
Dacite
Dacite dike
dike at
at Marquette
Marquette (figure
(figure 45).
45) .
41.
41.
210
210
Dacite
Dacite dike
dike in
in the
the Utley Quarry.
Quarry.
42.
42.
211
211
Andesite
Andesite dike
dike in
in the
the Utley Quarry.
Quarry.
43.
43.
193
193
Taylor Farm rhyolite.
Taylor
rhyolite.
major element
element analyses
analyses on
on Table
Table 6 (except
All major
#41 and
(except 'ft4l
and 42)
42)
were made
made using conventional wet-chemical methods
were
methods (K.
(K. Aoki,
Aoki,
analyst). Major element analyses 41 and 42 were
analyst).
were done
done by
0. Joensuu.
Joensuu. Trace element analyses (Rb,
O.
(Rb, Sr,
Sr, Pb
Pb and
and Zn)
Zn)
by atomic absorption spectrometry (0.
(0. Joensuu, analyst).
analyst).
All other trace
trace elements by optical emission spectrography
spectrography
(0. Joerisuu,
analyst).
(0.
Joensuu, analyst).
The
for Zr
Zr are
are accurate
accurate to
to
The result~
result for
±
107g.
Sr
and
Rb
are
accurate
to
± 10%. Sr and Rb are
to -- 5%
the amount present
present
5% of
of the
xcept for
~xcept
for low
low Sr
Sr (less
(less than
than 20
20 ppm)
ppm) which
which is
is accurate
accurate to
to
1070 of
-- 10%
of the
the amount
amount present.
present.
46
46
')
(
.5 MILES
0
zz
<{
a::
CD
EXPLANATION
rn
:E
<{
containing rounded
Friable quartz sandstone, locally containing
rounded
rhyolite fragments
C)
u
zz
<{
a::
CD
:E
<{
C)
u
Ui
lLI
a::
LII
E3
t"(\/]
0
~
I
Fine-grained
Fine - grained rhyolite dike
Coarse-grained
rhyolite dike
Coarse-grained rhyolite
rhyolite
Hill rhyolite
Observatory Hill
Q.
a-
Location of
Location
-+-
Figure 7.
Figure
7.
field
fi eld trip stops
Quarry
Vertical banding
Geologic
Hill adapted
adapted from
from Hobbs
Hobbs and
and Leith
Leith (1907).
(1907).
Geologic map of Observatory Hill
Approximate locations of field
field trip Stops
stops are superimposed.
Contour
interval 20
20 feet
feet between
between 800
800 and
and 960
960 feet;
feet; above
above 960
960 feet
feet the
the interinterinterval
val is
val
is 10 feet.
feet.
Contour
Contour lines
lines between
between 900
900 and
and 960
960 feet
feet are
are approxapproximately located.
located.
48
STOP 22 -- RHYOLITE
RHYOLITE AT
AT OBSERVATORY
OBSERVATORY HILL
HILL
STOP
Location:
Location:
Observatory
Observatory Hill
Hill (Hobbs
(Hobbs and
and Leith,
Leith, 1907)
1907) is
is one
one of
of five
five porphyritic
porphyritic
rhyolite inliers
inliers in
in south—central
south-central Wisconsin
Wisconsin (others
(others are
are at
at Endeavor,
Endeavor, Taylor
Taylor
rhyolite
Farm, Utley
Utley and
and Berlin).
Berlin). The
The hill
hill is
is formed
formed by
by steeply
steeply dipping
dipping flows
flows of
of
Farm,
quartz—and
quartz-and alkali
alkali feldspar—bearing
feldspar-bearing rhyolite
rhyolite tuffs,
tuffs, cut
cut by
by coarse—grained
coarse-grained and
and
fine-grained rhyolite
rhyolite dikes.
dikes. Observatory
Observatory Hill
Hill is
is surrounded
surrounded by
by outcrops
outcrops of
of
fine—grained
Upper Cambrian
Cambrian sandstone
sandstone and
and conglomerate
conglomerate (Fig.
(Fig. 7).
7).
Upper
The traverse
traverse to
to the
the summit
summit of
of Observatory
Observatory Hill
Hill will
will follow
follow an
an easy
easy but
but
The
It
is
Please
stay
together
during
the
climb.
sometimes
indistinct
trail.
Please
stay
together
during
the
climb.
It
is
sometimes indistinct trail.
Observatory
Hill.
quite
easy
to
become
lost
on
the
slopes
surrounding
Observatory
Hill.
quite easy to become lost on the slopes surrounding
Description:
Description:
Stop 2A
2A
Stop
The climb
climb to
to the
the summit
summit of
of Observatory
Observatory Hill
Hill begins
begins at
at exposures
exposures of
of Cambrian
Cambrian
The
sandstone just
just to
to the
the east
east of
of the
the bend
bend in
in Gillette
Gillette Road
Road (north
(north side
side of
of road)
road)
sandstone
of
rhyolite
The
outcrop
at
this
stop
is
about
300
m
to
the
south
(Fig.
7).
outcrop
at
this
stop
is
about
m
to
the
south
of
rhyolite
(Fig. 7).
outcrops on Observatory Hill and
and is
is composed
composed of aa friable
friable reddish—brown
reddish-brown quartz
quartz
No
fragments
of
rhyolite
are
found
here;
they
are
quite
common,
sandstone.
fragments
of
rhyolite
are
found
here;
they
are
quite
common,
sandstone.
however, in
in sandstone
sandstone exposures
exposures closer
closer to
to the
the rhyolite ledges.
ledges.
however,
Stop 2B
2B
Stop
Walk from
from stop
stop 2A
2A to
to the
the northwest over
over the
the low
low rise
rise to
to the
the first
first northnorththe
outcrops
of
sandstone
and
east
trending
valley
(Fig.
7).
Note
the
outcrops
Cambrian
east
valley (Fig. 7).
A conglomerate
conglomerate on the southeast side
side of
of the
the valley
valley (Fig. 8).
8). A
conglomerate
thick and
and contains
contains rhyolite
bed in this exposure is approximately 40 cm thick
cropping
m to
fragments
to rhyolite
rhyolite cropping out
out 200
200 m
to the
the north.
north.
fragments lithologically similar to
rounded
and
reach
10
cm
in
size
The
fragments
within
the
conglomerate
are
rounded
and
reach
10
cm
in
size
The fragments
are
pebbles in
Occasionally, quartzite
quartzite is
is found
found as
as small
small rounded
rounded pebbles
(Fig.
9). OCcasionally,
in the
the
(Fig. 9).
of
quartz—
The
source
of
these
clasts
may
be
in
the
large
area
conglomerate.
The
source
of
these
clasts
may
be
in
the
large
area
of
quartzconglomerate.
(Smith, 1978c)
1978c) or
or from
from vein
vein quartz
quartz
ite
ite to
to the
the northeast
northeast of
of Observatory Hill (Smith,
within the rhyolite.
Figure
Figure 8.
8.
View of
of Cambrian
Cambrian sandstone
sandstone outcrops
outcrops at
at stop
stop 2B
2B on
on the
the south
south flank
flank
View
of
49
of Observatory
Observatory Hill.
HIll.
Figure 9A.
Figure
9A.
Figure
Figure 9B.
9B.
Close—up of
of aa conglomerate
conglomerate layer
layer interbedded
interbedded with
with Cambrian sandClose-up
stone at stop
stop 2B.
2B.
In
fragments are angular (compare
(compare
In these
these bands,
bands, fragments
with Fig.
with
Fig. 9B).
9B). Most
Most of the fragments
fragments are
are porphyritic
porphyritic rhyolites
rhyolites
similar to
to those cropping out on Observatory
Observatory Hill.
Hill.
View
View of
of large
large rhyolite
rhyolite fragments
fragments (up
(up to
to 10
10 cm
cm in
in size)
size) in
in aa conconglomerate
glomerate layer
layer at
at stop
stop 2B.
2B. In
In this
this band,
band, fragments
fragments are
are rounded
rounded
(compare
(compare with
with Fig.
Fig. 9A).
9A).
50
50
o
On
On Observatory
Observatory Hill
Hill exposures
exposures of
of conglomerate
conglomerate containing
containing rhyolite
rhyolite pebbles
pebbles are
are
usually
usually restricted
restricted in
in occurrence
occurrence to
to aa zone
zone 55 to
to 20
20 mm wide
wide about
about the
the rhyolite
rhyolite
ledges. The
The conglomerate
conglomerate layer
layer at
at Stop
Stop 2B
2B is
is located
located an
an unusually
unusually large
large distance
distance
ledges.
from
from rhyolite
rhyolite exposures
exposures (200
(200 m),
m), and
and its
its deposition
deposition probably
probably reflects
reflects aa relatively
relatively
short lived
lived and
and highly
highly energetic
energetic event.
event. In
In the
the Baraboo
Baraboo region
region Dott
Dott and
and Dalziel
Dalziel
short
(1970)
(1970) reported large
large boulders of
of Baraboo Quartzite entrapped within Cambrian
sandstone. They
They envisaged
envisaged transport
transport of
of cobbles
cobbles and
and boulders
boulders by
by waves
waves and
and strong
strong
sandstone.
currents
currents generated
generated by
by violent
violent tropical
tropical storms
storms that
that pounded
pounded the
the Baraboo
Baraboo islands
islands
during Cambrian
Cambrian time.
time. Observatory
Observatory Hill
Hill probably
probably existed
existed as
as aa small
small island
island in
in
during
Strong
late
Cambrian
time
and
was
probably
also
hit
by
violent
tropical
storms.
late Cambrian time and was probably also hit by violent tropical storms.
Strong
currents
currents generated
generated during
during these
these storms
storms are
are probably
probably responsible
respon$ible for
for the
the transtransport
port of
of rhyolite
rhyolite fragments
fragments away
away from
from the
the Observatory
Observatory Hill
Hill island,
island, thus
thus forming
forming
the
conglomerate
band
observed
at
Stop
2B.
the conglomerate band observed at Stop 2B.
Stop 2C
2C
Stop
From Stop
Stop 2B
2B climb
climb the
the ridge
ridge above
above the
the sandstone
sandstone exposure
exposure and
and join
join aa trail
trail
Follow
this
trail
to
where
it
running along
along the
the crest
crest of
of the
the ridge.
ridge.
Follow this trail to where it joins
joins the
the
running
main
main trail
trail and
and then
then continue
continue up
up the
the hill on
on the
the main trail
trail (Fig.
(Fig. 7).
7).
Note the
the first
first outcrops
outcrops of
of rhyolite
rhyolite to
to your
your left
left and
and straight
straight ahead.
ahead. There
There
vicinity
is at least 500 feet
feet of relief on the Precambrian surface in
in the
the vicinity of
of
is
Observatory Hill.
Hill. Just ahead rhyolite exposures are
are at an elevation of
of 1080
1080
Observatory
northwest of
of Observatory
Observatory Hill,
Hill, rhyolite
rhyolite was
was enfeet. About
About 1200
1200inm to the
the northwest
feet.
countered in
in an irrigation
irrigation well at a depth of 300 feet
feet (480
(480 feet above
above sea
sea
level).
level).
Cross into
into the
the rhyolite exposures and
and continue to
to the
the trail
trail junction.
junction.
the trail
trail to
to the
the right
right (south).
(south). The fork to the
the left
left (north)
(north) goes
goes to
to
Follow the
1920's
the summit
summit where
where aa lookout
tower was
was once
once located
located in the
the
lookout tower
the early 1920's
The ruins
ruins of
of the
the tower
can still
still be
be observed
observed along
along the
(Fig.
7).
The
tower can
the inscriptions
(Fig. 7).
carved into the
rhyolite by
by several
several of
of the
the workers
workers who manned
manned the
carved
the rhyolite
the tower.
tower.
Follow the
trail (south)
to aa large
large area
area of
of bare
bare rock
rock which forms
Follow
the trail
(south) to
forms the
bluff).
sharp
the south bluff).
sharp southern
southern edge
edge of
of Observatory Hill
Hill (hereafter called
called the
rhyolite exposures
exposures (20
From the south bluff
bluff the
the Marcelloii
Marcellon rhyolite
(20 km to
to the
the south)
clear
and the
the Baraboo
Baraboo Hills
Hills (30
(30 km
km to
to the
the southwest)
southwest) can
can be
be easily
easily seen
seen on
on aa clear
and
At this
stop, we
we will
will examine
examine the
Hill rhyolite
rhyolite and a
day.
At
this stop,
the Observatory Hill
a
day.
coarse-grained
dike.
coarse—grained rhyolite dike.
Observatory
Observatory Hill
Hill Rhyolite
Rhyolite
rhyolites exposed
exposed
The Observatory
Observatory Hill
Hill rhyolite
rhyolite is
is typical
typical of
of porphritic
porphritic rhyolites
The
It contains
contains phenocrysts
phenocrysts of
of quartz
quartz (<
1 mm in
in
(~l
in size
size
in south-central
south—central Wisconsin.
Wisconsin. It
in size)
size) set
set in
and
in a
a
and rounded)
rounded) and
and pink
pink to
to white
white alkali
alkali feldspar
feldspar (1
(1 to
to 55 mm
mm in
On close
close examination,
examination, the
the matrix
matrix of
of the
the rhyolite
rhyolite
dark
dark gray to black matrix. On
and pumice
pumice fragments.
fragments.
shows
shows faint
faint flow
flow structure
structure formed
formed by flattened shards and
o
50°E.
The rhyolite
rhyolite is
In
E. The
is an
an
In general,
general, these
these bands
bands dip
dip steeply
steeply and
and strike
strike N.
N. 50
the entire
entire hill.
ash-flow
hill.
ash—flow tuff
tuff and
and is
is remarkably
remarkably texturally
texturally homogenous
homogenous over
over the
pheno—crysts
Petrographic studies
studies indicate
indicate that
that the
the rhyolite
rhyolite is
is composed
composed of
of pheno-crysts
Petrographic
The
devitrified ground-mass.
ground—mass. The
of
of quartz
quartz and
and alkali
alkali feldspar
feldspar set
set in
in aa coarsely
coarsely devitrified
51
51
quartz is
is anhedral
anhedral and
quartz
and is
is usually
usually strained
strained (7%).
(7%). Some
Some of
of the
the quartz
quartz is
is deeply
deeply
embayed. Alkali
Alkali feldspar
feldspar (23%)
(23%) is
is probably
probably orthoclase
orthoclase and
and may
may display
display carlscarlsembayed.
bad twinning.
twinning. Accessory
Accessory minerals
minerals are
are chlorite,
chlorite, biotite
biotite (?),
bad
epidote, iron
(?), epidote,
iron
oxide and
and zircon.
The matrix
matrix commonly
commonly contains
contains aligned
aligned and
and flattened
flattened Y
Y shaped
shaped
oxide
zircon. The
and cuspate
cuspate shards.
and
shards.
o
In terms
terms of
of major
major and
and minor
minor element
element chemistry,
chemistry, the
the rhyolite
rhyolite belongs
belongs to
to
In
chemical group
group 33 (Table
1, analysis
analysis 16;
16; Fig.
Fig. 6),
6), of
of Smith
Smith (1978a)
and is
chemical
(Table 1,
(1978a) and
is
therefore similar
similar in
in chemistry
chemistry to
to granophyric
granophyric granites
granites and
and porphyritic
porphyritic rhyorhyo—
therefore
lites in the Fox River Valley.
The group
group 33 rhyolites
rhyolites and
and granites
granites are
are
lites
Valley. The
distinguished
,
distinguished from
from other
other south-central
south—central Wisconsin
Wisconsin igneous
igneous rocks
rocks by
by high
high Si0
Si02,
2
K20/Na20,
La,
Zr,
Y
and
Rb/Sr;
and
low
CaO,
A1203
and
Ba
(Table
1).
K 0/Na 0, La, Zr, Y
Rb/Sr; and low CaO, A1 0 and Ba (Table 1).
2
2 3
2
Coarse—Grained Rhyolite
Coarse-Grained
Rhyolite Dike
coarse—grained rhyolite
dike strikes north south across Observatory
A coarse-grained
rhyolite dike
(Fig. 7).
The dike is about
m wide
wide at
(Fig.
7). The
about 70 m
at the south bluff but pinches out to
to
the north.
m thick)
dike of similar coarse—grained
the
north. A thin (15
(15 m
thick) dike
coarse-grained rhyolite
strikes N.
N. 50 E.
E. across the
strikes
the southeast
southeast slopes
slopes of
of Observatory
Observatory Hill.
Hill. These
dikes were
were originally identified by Hobbs and Leith (1907)
dikes
(1907) who referred
referred to
to
them as
as granite dikes.
them
The contact between the
the dike and the Observatory Hill rhyolite is well
displayed on the
east
edge
the
edge of
of the
the south
south bluff.
bluff. The contact shows complex
interfingering of
of dike
dike rock
rock into
into Observatory
Observatory Hill
Hill rhyolite
rhyolite (Fig.
10) and
and in
interfingering
(Fig. 10)
in
locality a
a rhyolite zenolith is
is found
found in
in dike
dike rock
rock close
close to
to the
the contact.
contact.
Locally the
Hill rhyolite is intensely fractured near the
the Observatory Hill
the contact
contact
(Fig.
11).
Also, quartz veins are concentrated on either side of the
(Fig. 11). Also,
the contact.
contact.
Extending 55 to
to 10
10 m
m into
into the
the dike from
from the
the intrusive
intrusive contact
contact is
is aa fine—
finegrained
contact
zone
(chill
zone?).
grained contact zone
zone?). The rock in this zone is
is gray—green
gray-green in
in
color and
and contains large
large plagioclase
plagioclase phenocrysts.
phenocrysts.
Petrographic
Petrographic studies
studies of
of the
the dike rock
rock of
of the
the contact zone
zone reveal
reveal sub—
subhedral
hedrHl zoned
zoned plagioclase phenocrysts (30%)
(30%) with cores altered to
to sausserite
sausserite
and unaltered
unaltered rims,
rims, subhedral alkali feldspar
feldspar (5%),
(5%), fractured and broken
quartz (3%)
(3%) and
and small
small subhedral
subhedral feather—like
feather-like grains
grains of
of biotite (1%).
(1%). The
matrix is
a
microbreccia
containing
fragments
of
fine—grained
is a
fragments of fine-grained rhyolite,
rhyolite,
basalt and
and eutaxitic
eutaxitic rhyolite.
rhyolite.
At this
this locality
locality also
also notice
notice the
the glacial
glacial polish
polish and
and grooving.
grooving.
glacial
striations
trend
N.
70°
W.
glacial striations trend N. 70° W.
Here
Here
Walk
Walk to
to the
the east
east of
of the
the south
south bluff
bluff to
to the
the first
first major
major outcrop.
outcrop. Here
Here
rhyolite
in
the
central
part
of
the
dike
is
well
exposed.
rhyolite in the central part of the dike is well exposed. This
This rhylite
rhylite is
is
similar
similar in
in mineralogy to
to that
that of
of the
the contact zone,
zone, but differs by
by having
having aa
coarser—grained
coarser-grained matrix
matrix than
than the
the contact—zone
contact-zone rock.
rock. Also,
Also, it
it is
is pink
pink to
to red
red
in
in color
color in
in outcrop,
outcrop, not
not green
green in
in color
color like
like the
the contact—zone
contact-zone rock.
rock. Petro—
Petrographic
graphic examination
examination indicates
indicates that
that plagioclase is
is the
the dominant phenocryst
phenocryst
(46%).
(46%). Alkali
Alkali feldspar
feldspar is
is present
present in
in micropegmatitic
micropegmatitic intergrowths
intergrowths with
with
quartz
quartz (21%).
(21%). Quartz,
Quartz, in
in addition
addition to
to its
its occurrence
occurrence in
in alkali
alkali feldspar—quartz
feldspar-quartz
52
52
Figure 10.
10.
Figure
View of the contact between the coarse—grained
coarse-grained rhyolite dike (below),
(below),
Hill rhyolite
rhyolite (above).
(above). Note
Note the
the fingers
fingers of
of
and the Observatory Hill
coarse—grained rhyolite
rhyolite extending
extending into
into the
the Observatory
Observatory Hill
coarse-grained
Hill rhyolite
rhyolite
Also
noteworthy
are
the
numerous
veins
of
quartz
(dashed line).
line).
veins
that
the contact.
contact.
that roughly parallel the
Figure
Figure 11.
11.
Close—up view
view of
of the
the shattering
shattering of
of the
the Observatory
Observatory Hill
Hill rhyolite
rhyolite
Close-up
at
dike.
at the
the contact
contact with
with the
the coarse-grained
coarse—grained rhyolite dike.
53
53
intergrowths,
intergrowths,
(10%) include
include
(10%)
oxide.
These
oxide.
These
is present
present as
as small
small anhedral
anhedral phenocrysts
is
phenocrysts (2%).
(2%). Accessory
Accessory minerals
minerals
chlorite in
in irregular
irregular clots,
clots, epidote,
epidote, clinozoisite,
clinozoisite, and
chlorite
and iron
iron
minerals are set
led groundmass
groundmass (21%).
set in
in aa finely
finely devitrif
devitrified
(21%).
This dike
dike and
and aa fine-grained
fine—grained granite at
This
at Baxter Hollow
Hollow (Gates,
(Gates, 1942)
1942) are
are
similar
in
chemistry,
and
form
chemical
group
1
of
Smith
(1978a)
similar in chemistry,
group 1 of Smith (1978a) (Table
(Table 1,
1,
analyses 11 and
The rocks
rocks are
are distinguished
distinguished from
from the
the other
other
analyses
and 2;
2; and
and Fig.
Fig. 6).
6). The
granites
and
rhyolites
in the
the Fox
Fox River
River Valley
Valley and
and Baraboo
Baraboo area
area by
by higher
higher
granites and rhyolites in
Ti02,, CaO,
CaO, Ba,
Ti0
Ba, V
V and Sr
Sr and
and by
by lower
lower Si02
Si0 and
and Rb.Sr
Rb.Sr ratio.
ratio.
Both
Both the
the ObserObser—
2
2
vatory Hill
Fox
ovatory
Hill rhyolite
rhyolite and
and the
the Baxter
Baxter Hollow
Hollow Granite are younger than the
the Fox
River Valley
Valley and
and Baraboo
Baraboo rhyolites.
Baxter Hollow
Hollow Granite
Granite intrudes
rhyolite
River
rhyolites. Baxter
intrudes rhyolite
(Gates, 1942)
1942) but
but its
its relationship
relationship to the overlying Baraboo
(Gates,
Baraboo Quartzite
Quartzite is
is
unclear (Dott
Daiziel, 1972).
unclear
(Dott and
and Dalziel,
1972). This
This stratigraphic
stratigraphic and
and chemical
chemical evidence
evidence
suggests that
that the
the intrusion
intrusion of
of the
the Baxter
Baxter Hollow
Hollow Granite
Granite and
and the
the Observatory
Observatory
suggests
Hill rhyolite
rhyolite was
was a
discrete igneous
event that
occurred after the
emplacement
Hill
a discrete
igneous event
that occurred
the emplacement
and folding
folding of
of the
the widespread rhyolite ash—flow
and
ash-flow sheets.
sheets.
The
for aa short
short time
time at
at the turn
The coarse-grained
coarse—grained rhyolite
rhyolite dike
dike was
was quarried
quarried for
of the
the century.
century. This
This opera~ion
operation is
evidenced by
by aa large
of
is evidenced
large area
area of broken dike
rock located just
just below and
and to
to the
the east
east of
of the
the south
south bluff.
bluff.
Labradorite Porphyry Dike
Dike
Hobbs and
east—trending "labradorite porphyry"
Hobbs
and Leith (1907)
(1907) reported
reported an east-trending
porphyry"
dike just to
to the
the north
north of
of the
the south
south bluff.
bluff. A
for this
this dike
dike
A careful search for
revealed an east-trending
east—trending fine—grained
quartz—feldspar rhyolite dike about
fine-grained quartz-feldspar
5
5 m
m in
in width.
width. This
This dike is
is truncated by the north—trending
north-trending coarse—grained
coarse-grained
rhyolite
rhyolite dike as
as is the "labradorite porphyry"
porphyry" dike described by Hobbs and
Leith.
In terms
terms of
of location,
location, orientation
orientation and
and stratigraphy,
stratigraphy, it
almost
Leith.
In
it is
is almost
certainly the
the same
same dike
dike mapped
mapped by
by them.
them.
In
In thin
thin section,
section, this rock contains
rounded
rounded and embayed quartz phenocrysts
phenocrysts (2%)
(2%) and alkali feldspar with perthitic
texture (altered
(altered to
to sericite
sericite and
and dusted
dusted with
with iron
iron oxide)
oxide) (3%).
(3%). These minerals
occupy a
a fine—grained
fine-grained matrix (devitrified)
(devitrified) with iron oxide accentuating a
a
crude
evidence of
crude banding
banding (95%).
(95%). The only evidence
of metabasalt on Observatory Hill is
found
found on
on the
the south
south bluff.
bluff. Here aa green metabasalt that
that occurs
occurs in
in an
an outcrop
outcrop
only 3 m
m long
long and
and 0.3
0.3 mm wide
wide may
may intrude
intrude rhyolite.
rhyolite.
Other
Other Exposures
Exposures of
of Porphyritic
Porphyritic Rhyolite:
Rhyolite:
Other
Other exposures of
of porphyritic
porphyritic rhyolite
rhyolite (Endeavor,
(Endeavor, Utley,
Utley, Berlin,
Berlin, and
and
Taylor Farm)
Farm) are
are mineralogically,
mineralogically, texturally,
texturally, and
and chemically similar
similar to
to the
the
rhyolite
rhyolite at
at Observatory
Observatory Hill.
Hill. However,
However, common
common in
in the
the Utley rhyolite
rhyolite are
are zones
zones
of
of spherulites
spherulites and
and lithophysae,
lithophysae, also
also disk—shaped
disk-shaped coarse—grained
coarse-grained inclusions
inclusions
may
may represent
represent recrystallized
recrystallized collapsed
collapsed pumice.
pumice. Rhyolite is
is locally
locally sheared
sheared at
at
Berlin (Weidman,
(Weidman, 1898)
1898) and
and slickensided
slickensided surfaces
surfaces are
are found
found at
at Utley
Utley (Gram,
(Gram,
1947).
1947). Rhyolite at
at Utley
Utley is
is intruded
intruded by
by rhyolite,
rhyolite, dacite
dacite and
and metabasalt
metabasalt dikes.
dikes.
54
54
1/
/
o
/
CC
~_
~ I ~~v'1'\:Y
N
t4
/'
.>..
~
t
J
~ (
--- -/
) /
(A/
(AI
J
~<
~4
~
/' EXPOSURES
EXPOSURES
/OF WELL
BANDED
WELL BANDED
?/ UNIT C
---- "---.,,,
~
--
~
UW DEEP HOLE
HOLE
)
WAYNE
/
BUSH
FARM
BUSH FARM
SPHEROIDS) I / f
~/u,,~ /
(~~~~
----
,..-
L BOX - PARK HERE
WELL
BANDED
UNIT B
QUARTZ
VEINS
EXPLANATION
---
-o
O
..
200
200 400
400FEET
FEET
I
4
4-
CONTACT
STRIKE AND
AND DIP
DIP OF
OF
STRIKE
FLOW BANDING
BANDING
FLOW
PLUNGING ANTICLINE
ANTICLINE
PLUNGING
PLUNGING SYNCLINE
SYNCLINE
PLUNGING
FIELD TRIP
TRIP ROUTE
ROUTE
,,~;~ FIELD
I''
-+-+-+- FENCE
FENCE
Figure
Figure 12,
12.
Route
Route map
map for
for traverses
traverses at
at the
the Marcellon
Marcellon rhyolite
rhyolite exposures,
exposures.
Letters
Letters A,
A, B,
B, CC refer
refer to
to Marcellon
Marcellon rhyolite
rhyolite unit
unit numbers
numbers (see
(see
text
text and
and Fig,
Fig. 13).
13).
56
56
STOP 33 -- THE
THE MARCELLON
MARCELLON RHYOLITE-SPHEROIDAL
RHYOLITE-SPHEROIDAL TEXTURES
TEXTURES
STOP
Location:
Location:
To
To reach
reach the
the outcrops
outcrops of
of spheroidal
spheroidal rhyolite
rhyolite we
we will
will walk
walk into
into the
the woods
woods
at
at the
the mail
mail box
box located
located across
across Monthey
Monthey Road
Road from
from the
the Wayne
Wayne Bush
Bush Farm.
Farm.
This
This traverse
traverse requires
requires aa bit
bit of
of climbing
climbing on
on bare
bare rock
rock that
that becomes
becomes quite
quite
slippery during
during wet
wet weather.
weather. Wear
Wear proper
proper field
field boots
boots and
and take
take considerable
considerable
slippery
care while
while on
on this
this traverse.
traverse.
care
(west)
(west)
This
This stop
stop will
will illustrate
illustrate several
several of
of the
the textural
textural types
types of
of rhyolite
rhyolite in
in the
the
Marcellon inlier.
inlier. See Figure
Figure 12
12 for
for the
the traverse
traverse route.
route. The
The rhyolite
rhyolite exposures
exposures
Marcellon
to
to the
the east of
of Monthey
Monthey Road
Road are
are described
described in
in aa supplemental
supplemental stop.
stop.
Introduction to the
the Marcellon Rhyolite:
Rhyolite: The
The Marcellon
Marcellon inlier
inlier (Hobbs
(Hobbs and
and Leith,
Leith,
1907;
1907; Smith,
Smith, 1978a)
1978a) is
is composed of texturally
texturally variable rhyolites
rhyolites similar
similar in
in
chemistry and
and lithology
lithology to
to rhyolites at the
the Marquette exposure (Stop
(Stop 4),
4), and
and
in the Baraboo
Baraboo area.
area. The Marcellon inlier
inlier is
is formed by four
four mineralogically and
and
chemically distinct ash—flow
ash-flow tuffs
tuffs folded into
into aa northeast striking
striking asymmetric
asymmetric
(and possibly overturned)
overturned) antiform
antiform (Fig.
(Fig. 13).
13). The western limb
limb of
of the
the antiform
antiform
(and
N. 500
50° E.
E. and
and dips
dips 50—85°
50-85° to
to the
the northwest.
northwest. The eastern limb
limb also
also
strikes N.
strikes
strikes N.
N. 50°
50° E.
E. but dips
dips steeply
steeply (80°
(80° to
to vertical)
vertical) to
to the
the southeast.
southeast. The
The
rhyolite
are cut
cut by a
northeast trending andesite dike and by an east
rhyolite flows
flows are
a northeast
(Table 1,
1, analyses
analyses 32
32 and
and 33).
33). The andesite
andesite dike
dike cuts
cuts
trending basalt dike (Table
and is
is therefore
therefore younger.
younger.
the basalt dike and
The structurally highest
A) at Marcellon
Marcêllon is a
The
highest unit
unit (unit
(unit A)
a sparsely porphy—
porphyritic
ritic plagioclase (1%),
(1%), quartz (2%),
(2%), alkali feldspar
feldspar (2%)
(2%) rhyolite characterized
diameter) composed of radiating
by abundant
abundant large spherulites
spherulites (up
(up to 15 cm in diameter)
On
the
fibers
of
alkali
feldspar
and
quartz.
On
the
eastern flank of the
the fold,
fold,
fibers
alkali feldspar and quartz.
spherulites are
are less
less distinct and
and smaller,
smaller, but
but still
still conspicuous.
conspicuous. Structurally
below unit
unit A is
is a
a rhyolite (unit
(unit B)
(6%), alkali
B) which contains sparse quartz (6%),
feldspar (4%)
feldspar
(4%) and plagioclase (1%)
(1%) phenocrysts in a
a banded matrix with
Several samples
samples show
show perlitic
perlitic cracks
cracks in
occasional
occasional faint
faint spherulitic growths. Several
characteristically
well
banded
and
contains
plagioclase
the
Unit
Unit C is
the matrix.
Bnnding in unit
as
(14-18%). B~nding
unit C is
is continuous and
as the
the dominant phenocryst (14—18%).
0
relatively
consistent
in
orientation
(N.
50°E.)
but
locally
broad westward
westward
relatively consistent in orient~tion (N. 50 E.) but locally broad
Several
lenses
of
spherulitic
rhyolite
plunging
exposed. Several lenses of spherulitic rhyolite lie
lie
plunging flow folds
folds are exposed.
Unit C
parallel
sharp contacts
contacts with
with nonspherulitic
nonspherulitic rock.
rock.
C
parallel to banding and have sharp
mineralogy to rock on
on the
on
the
on the
the eastern
eastern flank
flank of
of the
the fold
fold is
is similar
similar in
in mineralogy
The core
core of the antiform is
western flank,
flank, but it
it lacks
lacks conspicuous
conspicuous banding.
banding. The
is
(2%),
formed
(unit D)
formed by
by aa rhyolite
rhyolite (unit
D) which
which contains
contains phenocrysts
phenocrysts of
of quartz
quartz (2%),
plagioclase (15%)
and alkali
alkali feldspar
feldspar (2%)
in aa fine-grained
fine—grained devitrified
devitrified
plagioclase
(15%) and
(2%) in
groundmass
with
numerous
shards,
flattened
pumice
and
perlitic
fractures
groundmass with numerous shards, flattened pumice and perlitic fractures
All
units
at
are
interpreted
as
ash—flow
tuffs.
(Fig.
14).
All
Marcellon
ash-flow
tuffs.
(Fig. 14).
Marcellon includes:
Evidence
at Marcel10n
includes:
Evidence for
for the
the northeast
northeast striking
striking antiform at
(b)
geologic
map (Fig.
(a)
(Fig. 13);
13); (b)
(a) the
the symmetric
symmetric pattern
pattern of
of lithologies on the geologic map
rhyolite)
which
indicates
structural
(orientation of
structural data
data (orientation
of banding
banding within
within the
the rhyolite) which indicates
50° E.
E. and
and dips
dips to
to the
the
that
N. 50°
that the
the western
western part
part of
of the
the structure strikes N.
but
dips
steeply
to the
the
northwest;
the eastern part also
also strikes northeast,
northeast, but dips steeply to
northwest; the
rhyolite
The chemical
chemical correlation
correlation of
of lithologically
lithologically similar
similar rhyolite
southeast.
(c)
The
(c)
southeast.
Similarities in
structure. Similarities
from
the eastern flank of
of the
the structure.
in
from the
the western
western flank
flank to the
57
57
o0
250 500
1000
250
500 750
750 1000
2000 FEET
250
250
o0
500 METERS
N
1
:j
':·1
~
l:{:.
Basalt DIke
Baaalt
Dike
'f",$#!)
Quartz
Plagloclase
Alkali Feldspar
Quartz·- Plavlacla
.. -- Alkali
Feldapar Rhyolite
Rhyolite
.'
I, .......,/
:j176
YII76
::.::::rr-——,
....~';T
,.::.
:':.:::.)
)•_•
,,,
....~:.y
EXPLANATION
':6~
'/
Andesite
grained And..lte
Andesite Dike
And..lte Dike
Dike,• Coarse
Caar.. -—vralned
Dike
I,
'-
Unit
Unit D
D
Plagloclase
Plav1acla.. RhyolIte
Rhyolite
banded
and flaw
flow folded
banded and
folded
Unit
Unit C
C
Quartz—
Plagloclese
Alkali Feldlper
Feldiper Rhyollte
Quartz
- Plavlacla
.. • -Alkali
Rhyolite
Unit
Unit B
8
Spheruiitlc
Spherulllic Rhyellte
Rhyeille
U,dt
Utit AA
45
Strike
Strike and
and Dip
Dip .f
efBanding
Bandlnv
~+-
Vertical
Vertical Banding
BandlllV
-_
..
+-
~+-
Contect,
whereInferred,
lnf.rred, dotted
Contact, dashed
daahed where
dotted where
where
I4
burled
burled
Flow
Flow Foldln
Faldln,
Trace of
of axIal
axial Diane
,lane of
orrow indicates
Indlcat ..
Trace
of anticline,
enticllne, arrow
direction
direction of
ofplunge
plunve
Trece of
axialplane
plane of
of syncline,
Iyncllne, arrow
arrow indicates
Indlcat..
Trace
of xlal
direction
direction of
of plunge
plunve
Sample Location
Location
Sample
Antlcllne,
trace of
Anticline, showing
Ihowlnv trace
of azlal
axial plane
plane
Figure
Figure 13.
13.
Geologic
Geologic map
map of
of the
the Marcellon
Marcellon inhier
inlier (adapted
(adapted from
from Smith,
Smith, 1978a).
1978a).
58
58
Figure 14.
14.
Figure
Photomicrograph
Photomicrograph of cuspate and Y—shaped
Y-shaped shards
shards in
in the
the Marcellon
rhyolite ash—flow
ash-flow tuff
tuff (unit
(unit D).
D). Bar scale
scale is
is 11 mm
mm long.
long.
rhyolite
the
ratios of
of lithologically
lithologically similar
similar units
units (Table
(Table 1,
1, analyses
analyses 21—27)
21-27)
the Rb-Sr
Rb—Sr ratios
For
example,
both
spheru—
s.tratigraphically
suggest
that
they
are
&tratigraphically
equivalent.
For
example,
both
spherusuggest that they are
Similar
groupexposures (unit
(unit A)
A) show similar Rb/Sr
Rb/Sr values.
values.
Similar grouplitic rhyolite exposures
Unit D
D (Quartz_plagioclaSe—alkali
ings
for units
units B
Band
(Quartz-plagioclase-alkali feldfeldings are apparent for
and C. Unit
quartz—bearing rhyolites
by a
spar) can be distinguished from
from the
the other
other quartz-bearing
rhyolites by
a lower
lower
spar)
(2.82% as
as compared
compared with
with a
Fe20
Rb/Sr
and higher
0
(2.82%
a
Rb/Sr ratio and
higher Ba,
Ba, CaO,
CaO, and
and FeO ++ Fe
2 he other rhyolites by having a
1.77-2.13
%).
Also,
C
from
~he
other
rhyolites
by
having
a
unit
is
different
from
1.77—2.13 %).
higher
Ba content
content (Fig.
(Fig. 15).
15).
higher Ba
Bt-
DtD-
•
•
•
S
•
•
•
S
•
CtC
Bha. B
o0
Cf>
A CD
:>
I
100
100
~oo
500
Ba
Ba
Figure
Figure 15.
15.
1000
30 40 50
~o 60708090
60 70 80 90 00
0003040
La
La
I
~o
50
100
00
50
I~O
Sr
Sr
HI
00
100
ISO
I~O
Rb
Rb
2000
1.00
2.0
2.0
Rb/Sr
Rb/Sr
0)
0.5
O.~
1.0
1.0
CoO
CaO
.20
I.~O
0.5
Stratigraphic variation
variation in
in elemental
elemental concentrations
concentrations for
for the
the MarMar—
Stratigraphic
Ba, La,
La, Sr
Sr and
and Rb
Rb are
are in
in ppm;
ppm; CaO
CaO and
and MgO
MgO are
are
cellon
cellon rhyolite.
rhyolite. Ba,
For
comparison,
elemental
concentrations
for
in
in weight
weight percent.
percent. For comparison, elemental concentrations for
(from
Smith,
1978a).
the
Baraboo
rhyolites
(B)
are
also
plotted
the Baraboo rhyolites (B) are also plotted (from Smith, 1978a).
59
59
O.~
MO
MgO
Marcellon Traverse:
Walk into
into the
the woods
woods to the
the west
west
Marcellon
Traverse: Walk
Monthey
Road
from
the
Wayne
Bush
Farm.
See
Figure
12
Monthey Road from the Wayne Bush Farm. See Figure 12
at the
the mailbox located
at
located across
across
for
the traverse
traverse route.
for the
route.
Unit B
B
Unit
Note the
the well-banded
well—banded unit
unit BB rhyolite
rhyolite to
to your
your right
right in
in the
exposure just
Note
the exposure
just
to
the
west
of
Monthey
Road
(Fig.
12).
The bands
bands are
are discontinuous
discontinuous and
to the west of Monthey Road (Fig. 12). The
and are
are
formed by
by collapsed pumice fragments and
formed
and shards.
shards. At
At this
this exposure,
exposure, bands
bands
strike N.
N. 50°
500 E.
E. and
and dip
dip to
to the
the northwest
northwest at
at 50°
50° to
to 70°;
70°; thus
thus indicating
indicating the
the
strike
orientation of
orientation
of the
the west limb of the
the Marcellon
Marcellon antiform.
antiform. Band
is
Band orientation
orientation is
remarkably consistent
consistent in
in this
this area,
area, but
but several
several broad
broad folds
folds interrupt
this
remarkably
interrupt this
pattern.
In several
several places unit B is
pattern.
In
is spherulitic.
spherulitic.
Walk to the southwest along
along the
the margin
margin of
of the
the bluff.
bluff. Cross
Cross the barbedbarbed—
wire fence and
wire
and climb to
to the
the crest
crest of
of the
the bluff
bluff (Fig.
(Fig. 12).
12). As
ascend,
As you ascend,
note the
grooves in differentially weathered unit B rhyolite
note
the lichen
lichen growing in grooves
(the grooves
grooves are
are parallel
parallel to
(the
to the
the banding described
desc~ibed above).
above).
At
the crest of
At the
the bluff
bluff notice
notice the
the glacially
glacially polished
polished and
and striated
striated surface
surface (striations
the
(striations trend
trend
N. 70°
of milky quartz on the
N.
70° W.).
W.).
Also noteworthy are
are the
the large
large veins
veins of
south flank of
of the
the bluff.
bluff.
One
is 20 cm wide and
and over
over 66 mm long.
long.
One quartz
quartz vein is
Cross the
the summit
the hill
hill and descend
descend to its base (you
Cross
summit of
of the
(you should now be
on the
the west
west side
on
side of the hill and almost at
at its
its end)
end) (Fig.
(Fig. 12).
12). Notice that
that
as
hill is
east to west
west the
as the
the hill
is traversed
traversed from east
the banding so common in
in unit B
disappears and
and that
the rock becomes
becomes highly charged
charged with spheroids (characterdisappears
that the
(characteristic
istic of
of unit
unit A).
A). This
the contact between
between unit
unit BB and
and unit
unit A.
A.
This change marks the
Spheroidal
Spheroidal Texture
Texture
Unit A is a
a poorly—banded
poorly-banded ash—flow
ash-flow tuff with a
a spheroidal texture
texture
(Figure
(Figure 16).
16). Banding trends
trends N.
N. 20°E.
20 0 E. to
to N.
N. 30°
30° W.
W. and
and may
may swirl
swirl about
about
spheroids or may be truncated
truncated by
by them.
them. Three important types of spheroids
are
are present
present in
in this
this exposure.
exposure.
Figure
Figure 16.
16.
View
Vi~w of
of weathered
weathered spherulites
spherulites in
in the
the Marcellon
Marcellon rhyolite
rhyolite (unit
(unit C).
C).
These
These spheruljtes
spherulites are
are identical
identical to
to those
those observed
observed in
in unit
unit A.
A.
60
60
Spherulites
Spherulites composed
composed of
of radiating
radiating fibers
fibers of
of quartz
quartz and
and alkali
alkali feldspar
feldspar
A
small
alkali
feldspar
crystal
may
be
present
in
the
(Fig.
17).
A
small
alkali
feldspar
crystal
may
be
present
in
the core
core of
of the
the
(Fig. 17).
Spherulites
In
outcrop
they
appear
massive
and
may
be
broken.
spheroid.
In outcrop they appear massive and may be broken. Spherulites
spheroid.
commonly
commonly form
form by
by the
the devitrification
devitrification of
of volcanic
volcanic glass,
glass, and
and commonly
commonly occur
occur in
in
the
densely
welded
vitric
basal
zone
of
an
ash—flow
cooling
unit.
the densely welded vitric basal zone of an ash-flow cooling unit.
(1)
(1)
Spherulites
Spherulites are
are also
also quite
quite common
common in
in felsic
felsic lava
lava flows.
flows.
Spheroids with
with concentric
concentric bands.
bands. In thin section they
they are
are composed
composed of
of
Spheroids
alternating
led glass
alternating concentric
concentric bands
bands of
of coarsely
coarselyand
and finely
finelydevitrif
devitrified
glass (Fig.l8).
(Fig.18).
"Thesespheroids
spheroids may
may be
be concretionary
concretionary lapilli
lapilli (??).
(??).
These
(2)
(2)
(3) Lithophysae
Lithophysae with
with hollow
hollow cores
cores and
and in
in many
many cases
cases with
with drusy
drusy quartz
quartz lining
lining
(3)
In thin
the cavity
cavity wall.
wall. These
These spheroids
spheroids may
may not
not have
have aa central
central cavity.
cavity.
thin
the
section many of
of them
them have aa core
core of
of epidote,
epidote, and/or
and/or quartz
quartz (Fig.
(Fig. 19).
19).
The
The spheroids
spheroids have
have cross sections
sections that
that are
are nearly
nearly circular
circular (average
(average ratio
ratio
± 0.11).
of minor to
to major
major axis
axis == 0.71
0.71 ~
0.11). The cross sections of
of these
these
of length of
spheroids may be regarded as strain ellipses,
ellipses, and their
their nearly circular
suggests that
that these
these rhyolites
rhyolites were
were not
not strongly
strongly deformed.
deformed. Also
Also supportsupportshape suggests
ing this
this suggestion is
is the
the overall freshness of the
the rhyolites
rhyolites (there
(there is
is little
little
evidence for medium—
medium- or high—grade
high-grade metamorphism,
metamorphism, and
and original textures
textures are
are
in the
the matrix).
matrix). Also considering
considering their
their age,
age, these
these rocks
rocks are
are
preserved in
remarkably fresh
fresh in
in terms
terms of
of their
their chemistry
chemistry (Smith,
(Smith, l978a).
1978a).
Deep Well:
Well: Return
Return to
to Monthey
Monthey Road.
Road. Walk from
from the
the Bush Farm
Farm to
to the
the tree
tree
Deep
covered hill just to
to the
the north
north of
of the
the farm
farm (Fig.
(Fig. 12).
12).
The outcrop of well—
wellbanded unit
at the
base of
of the
hill was
was the
banded
unit C at
the base
the hill
the site of a
a deep hole drilled by
B. Haimson and students
students from the
the University of
of Wisconsin—Madison.
Wisconsin-Madison. Two
B.
ninety—seven feet
of core
core was
was recovered
hundred
and ninety-seven
feet of
recovered before drilling had to
hundred and
The
1978).
be stopped because of
of the
the extreme
extreme hardness
hardness of
of the
the rock
rock (Haimson,
(Haimson, 1978).
The
hole penetrated banded
banded unit
C. and
hole
unit C.
and then
then entered a
a poorly banded rhyolite
C. This
This poorly banded
banded rock is most probably
mineralogically identical
identical to unit
unit C.
separate ash-flow
ash—flow cooling
aa textural
textural variant
variant of
of unit
unit C.
C. and
and may
may represent
represent aa separate
Also, a
1 m thick
dike trending
trending N.
N. 26°E.
26°E. was
was intersected
intersected
unit.
Also,
aIm
thick inetabasalt
metabasalt dike
unit.
at
feet in
in the
the hole.
hole.
at aa depth of 132 feet
61
61
Figure 17.
Figure
17.
Figure
Figure 18.
18.
Photomicrograph of spherulitic texture in the Marcellon rhyolite
unit
These spherulites
spheruljtes are
are composed
composed of
of radiating
radiating fibers
fibers of
of
unit A.
A. These
quartz and
and alkali
alkali feldspar.
feldspar. Bar scale in
in 11 mm
mm long.
long.
Photomicrograph
Photomicrograph of
of aa spheroid
spheroid with
with concentric
concentric bands.
bands. Core
Core is
is
composed
composed of
of coarse—grained
coarse-grained quartz and
and alkali
alkali feldspar;
feldspar; rim
rim is
is
formed
formed by
by fine—grained
fine-grained quartz
quartz and
and alkali
alkali feldspar.
feldspar. Several
Several
spheroids
spheroids show
show alternating
alternating bands
bands of
of coarse—
coarse- and
and fine—grained
fine-grained
material.
material. Bar
Bar scale
scale is
is 11 mm
mm long.
long.
62
62
Figure
Figure 19.
19.
and
Photomicrograph of
of aa spheroid
spheroid with
with aa core
core of
of coarse
coarse quartz
quartz and
Photomicrograph
Quartz grains
grains are
are interlocking
interlocking and
and probably
probably grew
grew in
in aa
epidote.
epidote. Quartz
surrounded
The core
core is
is off-center
off—center within
within the
the spheroid
spheroid and
and is surrounded
cavity.
cavity. The
Many
of the
the
by aa band
band of
of fine-grained
fine—grained quartz
quartz and
and alkali
alkali feldspar.
by
feldspar. Many of
fine—
and
spheroids are
are more
more intricate
intricate and
and have
have alternating
alternating bands
bands of
of fine- and
spheroids
These
coarse—grained alkali
alkali feldspar
feldspar and
and quartz
quartz about
about the core. These
coarse-grained
Bar scale
scale is
is 11 mm
mm long.
long.
structures
structures may
may be
be lithophysae.
lithophysae. Bar
63
63
Supplemental Stop
Stop -— Flow
Flow Structures
Structures in
in the
the Marcellon
Marcellon Rhyolite:
Rhyolite:
Supplemental
This stop
stop illustrates
illustrates structures
structures and
and textures
textures in
in unit
unit C.
This
From
C.
From the
the Bush
Bush
Farm walk
walk to
to the
the north
north on
on Monthey
Monthey Road
Road to
to the
the tree
tree covered
covered knob
Farm
(Fig.
knob (Fig. 12).
12).
Turn right
right (east)
on the
dirt road
road (just
Turn
(east) on
the dirt
(just south
south of
of the
the hill).
hill). Walk
the
Walk~st
st the
drilling site
site (described
(described in
in Stop
Stop 3)
3) and
and continue
continue walking
walking for
for about
drilling
70
m
about 70 m
(Figure 12).
12). Turn
Turn left
left (north)
(north) into
into the
the trees
trees and
and follow
follow the
the "canyon"
"canyon" to
(Figure
to the
the
bare steep
steep exposure
exposure on
on the
the right
right (a
(a distance
distance of
of about
about 50
50 m,
bare
on
the
way,
m, on the way, you
you
should pass
pass aa large
large red
red granite
granite erratic).
erratic). The
should
The textures
textures described
described below
below are
are
located on
on this
this exposure.
exposure.
located
Unit CC is
is aa well-banded
well—banded rhyolite
rhyolite containing
containing plagioclase
plagioclase (15-25
(15—25 %)
Unit
as the
the
%) as
dominant phenocryst.
The unit
unit strikes
strikes N.
N. 30°
E. and dips steeply
dominant
phenocryst. The
30° E.
steeply 500
50° to
to 80°
80°
to the
the northwest
northwest (this
exposure is
to
(this exposure
is on the west limb
limb of
of the
the Marcellon
antiform).
Marcellon antiform).
Bands
are
discontinuous
and
are
in
general
lighter—colored
Bands are discontinuous and are in general lighter-colored than
than the
the matrix
matrix
(Fig. 20).
20). Many
Many bands
bands have
have aa dark
dark medial
medial line,
line, and
and in
in places
places they
they are
(Fig.
are observed
to bend
bend about
about phenocrysts.
phenocrysts. The
to
The bands
bands were
were formed
formed during
during primary
primary flowage
flowage and
and
compaction
of
an ash-flow
ash—flow tuff
tuff by
by shearing
shearing and
and compaction
compaction of
compaction of an
shards.
of pumice and shards.
Banded ash-flow
ash—flow tuffs
tuffs similar
similar to
to those
those observed
observed here
here are
Banded
in
are quite
quite common in
outflow
deposits
about
Tertiary
volcanic
centers
(Schmincke
outflow deposits about Tertiary volcanic centers (Schmincke and Swanson,
1967; Deal
Deal and
1967;
and Rhodes,
Rhodes, 1976).
1976). When viewed perpendicular to the foliation
plane,
these
Tertiary
ash—flow tuffs
tuffs display
display strong
strong lineation formed
plane, these Tertiary ash-flow
formed by
flattened
pumice
(Fig.
21).
flattened pumice (Fig. 21). The
be 20
20 to
to 11 on
the
The axial
axial ratio of pumice may be
on the
flow plane,
plane, and
flow
and as
as high
high as
as 200
200 to
to 1
1 on
to the
the flow
flow surface
surface
on the
the plane normal to
and parallel
parallel to
and
to the
the direction
direction of
of flow.
flow.
Where pumice shows a
a high degree of
stretching and
flattening
the
rock
and
the rock may
may resemble
resemble aa flow-banded
lava, but the
the
flow—banded lava,
presence of glass shards
shards and the discontinuous nature of the bands suggests
suggests
instead that
that the
the rock
rock is
highly foliated
foliated ash-flow
ash—flow tuff
instead
is aa highly
(Smith, 1978b).
1978b).
tuff (Smith,
The banding at this locality is
is folded
folded into aa series
anticlines
series of broad anticlines
and synclines that
plunge
steeply
(50°
that plunge steeply (50° to
to 80°)
80°) to the
the west.
west. Fold amplitudes
amplitudes
are as great as
as 30
30 mm and
and wavelengths
wavelengths vary
vary up
up to
to 10
10 m.
m.
In most
most cases where aa
fold
nose
is
observed,
the
plunge
of
the
fold
fold
is observed, the plunge of the fold axis parallels the
the dip
dip of
of unit
unit
C
C as
as aa whole.
whole. Fold
Fold limbs
limbs are
are themselves
themselves folded
folded into antiforms and synforms
synforms
that plunge steeply
steeply to
to the
the west
west (Fig.
(Fig. 22).
22). These minor
minor folds
folds have amplitudes
amplitudes
of
up
to
10
m
and
wavelengths
that
of up to 10 m and wavelengths that vary
vary from
from several
several centimeters
centimeters to
to several
several
meters.
meters. Flow
Flow bands
bands on
on fold
fold limbs
limbs may
may truncate
truncate each
each other,
other, also fold crests may
may
not
not completely
completely close,
close, forming
forming fanning
fanning patterns
patterns (Fig.
(Fig. 23).
23).
The
ae interpreted
The folds
folds:re
interpreted as
as ramp
ramp structures
structures formed
formed during
during the
the flowage
flowage of
of an
an
ash—flow
tuff.
ash-flow tuff. In
In detail
detail they
they are
are formed
formed by
by compressional
compressional buckling
buckling and
and thrustthrusting
ing of
of the
the upper
upper part
part of
of an
an ash—flow
ash-flow cooling
cooling unit
unit over
over aa more
more fluidal
fluidal interior
interior
(Smith,
1978b).
In
Tertiary
ash—flow
(Smith, 1978b).
In Tertiary ash-flow tuffs
tuffs ramp
ramp structures
structures are
are broad
broad warps
warps in
in
the
the flow
flow foliation
foliation that
that resemble
resemble large
large folds
folds in
in felsic
felsic lavas.
lavas. Amplitudes
Amplitudes are
are
up
up to
to 50
50 mm and
and wavelengths
wavelengths vary
vary from
from several
several meters
meters to
to tens
tens of
of meters.
meters. Many
Many
are
asymmetric
with
gentle
limbs
dipping
10°
to
30°
sourceward,
are asymmetric with gentle limbs dipping 10° to 30° sourceward, and
and are
are convex
convex
upward
upward (Schminke
(Schminke and
and Swanson,l967).
Swanson,1967).
64
f14
20.
Figure 20.
Highly flattened
and sheared
sheared pumice
pumice and
and shard
shard fragments
flattened and
fragments forming
forming a
a
pronounced lineation
lineation in
in the
the Marcellon
Marcellon rhyolite
rhyolite (unit
(unit C).
C). The
The bands
bands
colored than
are discontinuous and
and are
are in
in general
general lighter
lighter colored
than the
the matrix.
matrix.
Note that
that several bands
bands trend
trend to
to form
form about
about cavities
cavities and
and phenocrysts.
phenocrysts.
Figure
Figure 21.
21.
Close—up of
of lineation
lineation formed
formed by
by highly
highly flattened
flattened and
and stretched
stretched
Close-up
pumice in
in the
the Tertiary
Tertiary A.
A. L.
L. Peak
Peak Tuff,
Puff, San
San Mateo
Mateo Mountains,
Mountains, New
New
pumice
The
strong
lineation
formed
during
the
late—stage
laminar
Mexico.
The
strong
lineation
formed
during
the
late-stage
laminar
Mexico.
Also note
note the
the numerous
numerous rotated inclusions.
flowage
flow. Also
inclusions.
flowage of
of the
the ash flow.
65
65
Figure
Figure 22A.
22A.
A large steeply plunging flow fold
fold in the Marcellon rhyolite
The fold
fold axis
axis strikes
strikes N.
N. 50°
5Ø0 W.
W• and
and plunges
plunges 8So
85° to
to
(unit C).
C). The
The plunge of the fold axis
the west. The
axis parallels
parallels the
the dip
dip of
of unit
unit
as aa whole.
Dashed line traces
C as
Dashed
traces the limbs
limbs of
of the
the fold.
fold.
Figure
Figure 22B.
22B.
AA small
small fold
fold in
in the
the Marcellon
Marcellon rhyolite
rhyolite (unit
(unit C).
C). This
This structure
structure
probably
probably formed
formed during
during primary
primary flowage
flowage of
of the
the ash—flow
ash-flow tuff.
tuff. Its
Its
axis
axis strikes
strikes east—west
east-west and
and plunges
plunges 60°
60° to
to the
the west.
west.
66
66
I
23A.
Figure 23A.
I foot
Sketch of a fold
fold in
in the Marcellon rhyolite unit C
C where
does not
completely
close
producing
a
fanning
pattern.
not completely close producing a fanning pattern.
truncation of
of banding.
banding.
fold
fold
Also
Also
crest
crest
note
note
O.5m
0.5 m
Figure
23B.
Figure 23B.
Sketch of
of aa large
large fold
Sketch
fold in Marcellon rhyolite
rhyolite unit
unit C.
C.
steeply
(left).
steeply to
to the
the west
west (left).
67
67
Fold plunges
Fold
plunges
STOP 44 -- THE
THE MARQUETTE
MARQUETTE RHYOLITE
RHYOLITE(NORTH
(NORTh OF
OF COUNTY
COUNTY HIGHWAY
STOP
HIGHWAYH)
H)
Location: The
The stratigraphy
stratigraphy and
and fabric
fabric of
of the
the Marquette
Marquette rhyolite
rhyolite to
Location:
to the
the north
north of
of
County
Highway
H
will
be
examined
at
this
stop.
County Highway H will be examined at this stop. AA supplemental
supplemental stop
stop views
views
banding, pumice
pumice lenses
lenses and
and aa block-flow
block—flow breccia
breccia in
in exposures
banding,
exposures to
to the
the south
south of
of
County HH on
on Ingall's
Ingall's knob.
knob. See
See Figure
Figure 24
24 for
for traverse
traverse routes.
routes.
County
EE
--
r
N
t4
STOP
400 FEET
400
FEET
=
/)
I
z-
UNIT B
—,
' — FIAMME
BR EC CIA
EXPLANATION
CEJ
GEOLOGIC
GEOLOGIC UNIT
UNIT
.---
CONTACT
CONTACT
_——--
~
Figure
Figure 24.
24.
-+--t-+-
see
see text
text for
for
xpI
an at ion
'3xplanation
PLUNGING
PLUNGING ANTICLINE
ANTICLINE
—-----. ' -
GATE
GATE
~
TRAIL
TRAIL
--:yo
PLUNGING
PLUNGING SYNCLINE
SYNCLINE
FENCE
FENCE
FIELD TRIP
FIELD
TRIP ROUTE
ROUTE
Route
Route map
map for
for traverses
traverses at
at the
the Marquette
Marquette rhyolite
rhyolite exposure.
exposure.
Introduction
Introduction to
to the
the Geology
Geology of
of the
the Marquette
Marquette Exposure:
Exposure:
The
The rhyolite
rhyolite at
at Marquette
Marquette (Pretts,
(Pretts, 1895;
1895; Hobbs
Hobbs and
and Leith,
Leith, 1907;
1907; Smith
Smith and
and
Hartlaub,
Hartlaub, 1974;
1974; Smith
Smith l978a)
1978a) occupies
occupies seven
seven small
small hills
hills surrounded
surrounded by
by PleisPleistocene
tocene sediments
sediments and
and Paleozoic
Paleozoic sedimentary
sedimentary rocks
rocks (Fig.
(Fig. 25).
25). The
The extensive
extensive
cover
cover prevents
prevents reliable
reliable field
field correlation
correlation of
of units
units from
from hill
hill to
to hill,
hill, and
and
since
most
contacts
are
obscured,
relative
since most contacts are obscured, relative age
age of
of the
the Marquette
Marquette units
units can
can only
only
be
be inferred
inferred by
by noting
noting their
their stratigraphic
stratigraphic position
position within
within major
major folds.
folds. CorreCorrelations
lations depicted
depicted on
on the
the geologic
geologic map
map (Fig.
(Fig. 25)
25) are
are based
based primarily
primarily on
on chemical
chemical
68
68
"'J
fool·
I-'.
(J'q
—
'i
CD
CD
~
l!..:I
U1
.
~
....
C'l
CD
El
2
ll>
"0
'i
.c
t:
ffi
CD
CD
C"t
C"t
CD
CD
1-4
H
::s
....
I-S
fool·
i-a.
CD
CD
'"i
Plagioclose Rhyollte
Plagioclase
Rhyolite
Volts EE and
Units
and C
C
V.~~;ij
Breccia
Breccia
ILI'/-
E$KtFJ
C.
Strike and
dip of
of contact
Strike
and dip
contact
Normal fault,
fault, dashed
Normal'
dashed where
where
,~
approximately
located,
approximately
located, UUD
.... ""U
upthrown
upthrown side,
side, D-downthrown
D-downthrawn
,,""
Antlcllne,
trace of
Anticline, showing
showing trace
of
axIal plane
directIon
axial
plane and
and direction
)'7
,,""
Syncline,
trace of
Syncline, showing
showing trace
of
axial
dIrection
axial plane
plane and
and direction
of plunge
of
plunge
Overturned Anticline,
Overturned
Anticline,showing
showing
trace
trace of
of axial
axial plane
plane and
and
direction of
direction
of plunge
plunge
c' Overturned
",""
Overturned Syncline,
Syncline,
l'
showingtrace
trace of
of axial
showing
axial
plane and
and direction
direction of
plane
of
plunge
plu n g e
)
I
I
I
I
I
— Sample
SampleLocation
Location
I
I
I
I
Quarry
,.
1
.1.
.1
I
I.
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4'KK)"
/
~,
,
,,
.•I.
\
ll>
c-lC"t
CD
CD
y
""y
~...,
Andeslte C?)
Andesite
(f) Dikes
Dikes
Fine- Gralned Rhyolite
Rhyollte Dike
Fine-Grained
Dike
8
':• •
ll>
""
C.
"0
Vertical
Vertlcol banding
bonding
of plunge
of
plunge
Very fine-grained rhyolite.
coarsely porphyritic rhyolite
H>
~
StrIke and
Strike
and dip
dip of
of banding
bonding
s
side
side
[2]
L Very fine—gralned rhyollte,
rn
coarsely porphyritic rhyollte
0
CD
CD
Quartz
Quar
t z- Plagloclase
P 10 g I ocla se - AlkalI
AI ka II
Feldspar
Feldspar Rhyollte
Rhyolite
,'/ '
1/oils B,O,F
8,O,F and
Units
and A
A
(J'q
o.q
fool·
i-S.
C"t
Porphyritic Quartz-Alkali
Porphyritic
Quartz-Alkali FeldFeldspar
Rhyollte with
spar Rhyolite
with interbedded
Interbedded
flne-gralned
rhyollte flow
fine-grained rhyolite
flow
(Jolt 6
Unit
G
D
0
0
I-.
0
::r
Contact,
dashed where
where InInContact. dashed
(erred,
ferred, dotted
dolled where
where burled
burled
-.
~'
EXPLANATION
t:
I
N
N
,
\
t
..CLUPPER1S
CLUPPER1"S
HILL
H,
H>
'i
0
0
2
El
'60
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2
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fool·
HC"t
....
0
....I-I
1.0
0
.
::r
....:t
—1
00
a,
OJ
'-'
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250
!SOO
500
7'0
750
10'00
000
2000
20'00
FEET
FE
ET
•
INGALLS
KNOB
2.!50
250
xoo METERS
!SOO
METERS
i
________________
and petrographic
petrographic similarities.
and
similarities.
The inlier
inlier is
is formed
formed by
by seven
seven mineralogically
mineralogically and
and chemically
chemically distinct
distinct
The
volcanic
flows,
ash—flow
tuffs,
and
breccias.
volcanic flows, ash-flow tuffs,
The
The units
units lettered
lettered A
A to
to G from
from
southeast to
to northwest
northwest are
are broadly
broadly folded
folded into
into aa series
series of
of normal
normal and
and oversoutheast
overturned anticlines
anticlines and
and synclines
synclines with
with an
an average
average wavelength
wavelength of
of 300
300 m.
turned
The
m.
The
fold axes
axes strike
strike N.
N. 200
N. 400
fold
20° to N.
40° E.
E. and plunge
plunge to
to the
the northeast.
northeast.
These
These
folded rhyolite
rhyolite units
units are
are cut
cut by
by aa 100
100 m
m thick
thick andesite
andesite dike
dike (Table
1, analysis
analysis
folded
(Table 1,
30)
which
was
intruded
along
a
northeast
trending
normal
fault.
30) which was intruded
a
trending normal fault.
The
The fault
fault
is downthrown
downthrown to
to the
the north,
north, and
and the
the displacement,
displacement, calculated
calculated by
by estimating
estimating the
is
the
amount of
of structural
structural shortening,
shortening, probably
probably does
does not
not exceed
exceed 600
600 m.
amount
The
m.
The structures
structures
to the
the north
north of
of the
the fault
fault have
have aa one
one to
to one
one correspondence
correspondence to
to those
those to
to the
the
to
south, except
except that
south,
that they are displaced to
to the
the southwest.
southwest. While the
the map
shows
map shows
simpler structural
structural patterns
patterns to
to the
the north
north of
of the
the fault
fault then
then to
to the
the south,
south, this
this
simpler
difference is
probably due
due to poor
poor structural
structural control
control to
difference
is probably
to the
the north of the
fault.
fault.
The youngest
youngest rock in
northeast trending fine—grained
The
in the
the inlier
inlier is
is aa northeast
fine-grained
massive dacite
dacite dike,
dike, 35
35 m
m thick,
which cuts
cuts the
fault and
dike
massive
thick, which
the fault
and the
the andesite
andesite dike
(Table 1,
1, analyses 39
The dike
dike is
unit C in lithology
(Table
39 and
and 40).
40).
The
is similar to unit
(fine—grained with
with plagioclase
plagioclase as
as the dominant phenocryst),
(fine-grained
phenocryst), but
but it
it is
is disdistinguished from unit
unit C
C on
on chemical
chemical grounds
grounds (Fig.
(Fig. 26).
26).
89 "ioo
G—.-•\
\106\
'I98 !1194
—II
10
10
i'92.—B
I
/
'
9
Rb!
Rbi
/Sr
I Sr
97 'I
—
jP5
!e'P5
191
(i ', ,
191 (.......
Rhyolite
Rhyolite
dike
dike
,
\ \ "Andesite"
\ \ dOk
..... ....
\ \ \dike
I e
~ \
190' \ \
.....
I9O \,
\
,
~.J 189
189
0
0
l.a
1.8
Na20/K20
Figure
Figure
26.
26.
°
Rb/Sr—Na20/K
Rb/Sr-Na 2 0/K 0 plot
plot for
for Marquette
Marquette inlier
inlier samples.
samples. This
This plot
plot de~
de
monstrates
monstrates tat
t5at mineralogically
mineralogically similar
similar rhyolites
rhyolites can
can be
be distindistinguished
guished on
on the
the basis
basis of
of Rb/Sr
Rb/Sr and
and Na20/K20
Na O/K
ratios. Also
Also note
note the
the
ratios.
cyclic
cyclic change
change in
in Rb/Sr
Rb/Sr ratio.
ratio. Plagioclase_bearing
Plagi~cla~e-bearingrhyolites
rhyolites (unit
(unit
CC and
and E)
E) have
have Rb/Sr
Rb/Sr greater
greater than
than 1,
1, whereas
whereas quartz—plagioclase_
quartz-plagioclasealkali
alkali feldspar
feldspar rhyolites
rhyolites (units
(units B,
B, D,
D, and
and F)
F) have
have Rb/Sr
Rb/Sr less
less than
than
1.
1. Unit
Unit GG is
is the
the quartz—alkali
quartz-alkali feldspar—plagioclase
feldspar-plagioclase rhyolite
rhyolite
(from
(from Smith,
Smith, l978a).
1978a).
°
70
70
unit GG is
is aa thick
thick (1000
(1000 m)
m) quartz
quartz (10
(10 %),
%), alkali
alkali feldspar
feldspar (commonly
(commonly perth—
perthUnit
Except
for
minor
porphyry.
rhyolite
thitic)
(16
%)
and
plagioclase
(7
%)
rhyolite
porphyry.
Except
for
minor
plagioclase
(7
%)
and
thitic) (16 %)
variations
variations in
in phenocryst
phenocryst abundance
abundance and
and faint
faint banding,
banding, the
the unit
unit is
is texturally
texturally
Shard—like
forms
were
observed
in
the
matrix
of
unit
G,
homogeneous.
Shard-like
forms
were
observed
in
the
matrix
of
unit
G, indicating
indicating
homogeneous.
it is
is an
an ash—flow
ash-flow tuff.
tuff. AA fine—grained
fine-grained rhyolite
rhyolite is
is interbedded
interbedded with
with
that it
unit
unit G,
G, and
and crops
crops out
out near
near the
the south
south end
end of
of the
the unit
unit GGexposure.
exposure.
The
The 66 units
units lying
lying to
to the
the southeast
southeast of
of unit
unit GG are
are texturally
texturally variable,
variable, with
with
banded,
banded, fine—grained
fine-grained and
and porphyritic
porphyritic varieties
varieties common.
common. Most of
of the
the units
units show
show
evidence
~vidence of
of brecciation
brecciation and
and micro—brecciation.
micro-brecciation. Coarse
Coarse breccia
breccia is
is found
found on
on the
the
southeast
southeast margin of Ingall's
Ingall's Knob where clasts of
of porphyritic
porphyritic and
and fine—grained
fine-grained
red to
to black
black rhyolite
rhyolite exceed
exceed 10
10 mm in
in size.
size. Unit D
D on
on Cluppert's Hill is
is also
also
Eutaxitic
texture
is
well
displayed
in
several
of
extensively brecciated.
brecciated.
texture is
displayed in several of the
the
extensively
units.
units.
Each unit
unit in
in the
the Marquette inlier
inlier has distinguishing chemical
chemical and
and
mineralogical characteristics which are
used
to
correlate
units
between
are used to correlate units between
(Fig. 46,
46, Table
Table 1,
1, analyses
analyses 4—14).
4-14). Units
Units A,
A, B,
B, D,
D, and
and FF are
are porphy—
porphyexposures (Fig.
ritic
ritic plagioclase (18
(18 to
to 27%),
27%), quartz (2
(2 to
to 8%),
8%), and
and alkali
alkali feldspar
feldspar (1
(1 %)
%)
20 to
to 36
36 %
% total
total phenocrysts.
phenocrysts. Unit B is
is distinguished from
from
rhyolites with 20
the other quartz bearing rhyolites by Na
Na20/K20
0/K 0 greater than 1.0 and
and low
low Rb/Sr
2
2
0.92). Unit D
D and Unit F
P are similar in
in both major and
and minor element
(0.64 —- 0.92).
however, contains in its upper part aa 100 m
D, however,
m thick
thick massive
chemistry. Unit D,
phase;
similar massive
masive rock
phase; aa similar
rock is
is not
not associated
associated with
with unit
unit F.
F. To date,
date, no
Units
C
and
E
are
I
ine--grained
been made
made on
on unit
unit A.
A.
Units C and E are fine-grained
chemical studies have been
(10 to 15
15 %% phenocrysts) with plagioclase
plagioclase as
as the
the dominant
dominant phenocryst.
phenocryst. Unit E
(10
is
C by lower
lower CaO.
CaO.
is distinguished
distinguished from unit C
Noteworthy is the cyclic change from phenocryst—poor
phenocryst-poor plagioclase
rhyolite (units
E) to phenocryst—rich
(units C and E)
phenocryst-rich three—mineral
three-mineral rhyolite (units
(units B,
B,
D,
and F).
F). This cyclic variation in mineralogy is
is also reflected in
in trace
trace
D, and
element chemistry (Table
(Table 1,
1, analyses 4—14);
4-14); for example,
example, Rb/Sr ratios
ratios vary
vary
from 1.45
1.45 to
to 1.23
1.23 for
for units
units EE and
and C and
and from
from 0.71
0.71 to 1.0 for
from
for units
units F,
F, D,
D, and
B (Fig.
(Fig. 26).
26).
Chemical and flow direction data (Smith,
(Smith, 1978a)
1978a) show that
that all
all of
of the
the
Marquette units are comagmatic and that all flows
flows erupted from
from aa source
source to
to
This evidence
evidence suggests
the
outcrops. This
suggests that
that cyclic
the northwest of the present outcrops.
variation in
chemistry, mineralogy,
mineralogy, and
texture reflect
reflect eruption from a
variation
in chemistry,
and texture
a
differentiating source.
source. Fine—grained
Fine-grained units probably represent eruption
eruption from
from
On the
the other
other hand,
hand, more
more highly porphyritic
fractionated
crystal-poor magma. On
fractionated crystal—poor
varieties may
may represent
represent eruption from
from zones
zones of
of crystal
crystal accumulation within
varieties
The lower
lower Rb/Sr
Rb/Sr ratios
ratios in phenocryst
phenocryst and
the source chamber.
chamber. The
and feldspar rich
units (F,
and B)
B) may
may be
be explained
explained by aa model
model where
where Sr is
units
(F, D and
is concentrated into
As a
the crystallizing feldspar and
the
and Rb
Rb is
is enriched
enriched in
in the
the liquid
liquid phase.
phase. As
a
consequence phenocryst
phenocryst and
rich units
would have
have lower Rb/Sr than the
consequence
and feldspar
feldspar rich
units would
the
fine—grained, feldspar-poor
feldspar—poor varieties
varieties (units
(units C
C and
and E)
E) which
which formed
formed from
from
fine-grained,
fractionated,
crystal- and
and feldspar—poor
feldspar-poor magma.
magma.
fractionated, crystal—
Alternately, fine—grained
Alternately,
fine-grained and
and phenocryst—rich
phenocryst-rich pairs
pairs may represent
compositionally zoned
zoned ash-flow
ash—flow sheets
sheets with
with the
the phenocryst-rich
phenocryst—rich unit
unit at
at the
compositionally
the
Zoned ash-flow
ash-flow tuffs
tuffs commonly
commonly
top
at the
the base.
base.
Zoned
top and
and the
the fine-grained unit at
show an
an upward
upward increase
increase in
in MgO,
MgO, CaO,
CaO, A1
Al203,
TiO2 and
and Sr/Rb
Sr/Rb and
and may
may vary
vary in
0 , Ti0
show
2 3
2
71
71
from quartz
quartz latite
latite at
at the
top to rhyolite
rhyolite at
composition from
the top
at the
the base (for
(for example
see Smith,
Smith, 1960;
1960; Ratte
Ratte and
and Steven,
Steven, 1964;
1964; Smith
Smith and
and Bailey,
Bailey, 1966;
1966; Noble
Noble and
and
see
Hedge, 1969;
1969; and
Phenocryst abundance,
abundance, and
and xenolith
xenolith abundance
abundance
Hedge,
and Rhodes,
Rhodes, 1976).
1976). Phenocryst
and size
size usually
usually increase
increase upward,
upward, with
with pumice
pumice commonly
commonly showing
showing reverse
reverse zonation
zonation
and
(Sparks, 1976).
ash—flow sheet
sheet the
(Sparks,
1976). Within one
one ash-flow
the transition from phenocryst—poor
phenocryst-poor
to phenocryst-rich
phenocryst—rich tuff
tuff can
can be
be abrupt
abrupt (Noble,
1970). Marquette
Marquette units
units FF and
and EE
to
(Noble, 1970).
may
together
represent
a
single
compositionally
zoned
ash—flow
sheet
with
unit
may together represent a single compositionally zoned ash-flow sheet with unit
B
the
differentiated
fine—grained
base
and
unit
F
the
less
differentiated
pheno—
E the differentiated fine-grained base and unit
the less
phenocryst-rich top.
Grouping of
of units
units D
D and
and C
C is
is doubtful
doubtful since
since they
they are
are separated
separated
cryst-rich
top. Grouping
. by a
a fault
fault and by an
an andesite
andesite dike.
dike. More
More detailed
detailed field
field and
and chemical
chemical data must
be
obtained
before
this
be
this model
model can
can be
be properly
properly evaluated.
evaluated.
The Marquette Rhyolite Traverse:
The
Stop 4A —
Unit CC
Stop
- Unit
Walk due
then
turn to
to
then turn
north from the
the locked
locked gate on
the
woods
(east)
the woods (east) to the
the first
first
the
the north side
side of County Highway H,
H,
exposure
(see
exposure (see Fig.
Fig. 24
24 for
for the
the route).
route).
This exposure
exposure is
formed by
by a
plagioclase—bearing rhyolite
rhyolite ash—flow
This
is formed
a plagioclase-bearing
ash-flow tuff
tuff
(unit C).
It contains
contains small
small (up
to 55 mm
mm in
in size)
size) anhedral
anhedral to
to subhedral
subhedral plagioplagio—
C).
It
(up to
clase laths
set in a
fine—grained matrix
matrix that
brown.
clase
laths set
a black fine-grained
that is
is streaked reddish brown.
Unit C is
well banded,
banded, and
and may
may also
also display spherulitic and
Unit
is commonly well
and brecciated
texture.
texture.
At this
this locality,
locality, bands stand out prominently due to
to differential
erosion. The bands form the
erosion.
the reddish—brown
reddish-brown streaks,
streaks, and
and under
under careful scrutiny
scrutiny
they
are observed
observed to be
be composed
composed of
discontinuous lenses
lenses of collapsed pumice
they are
o£ discontinuous
and shard fragments.
fragments. The banding trends
trends N.
N. 60 E.
E. and dips 85° south
south or
or is
is
vertical.
Since this
exposure is
on the
flank of
of a
northeast plunging
vertical.
Since
this exposure
is on
the south flank
a northeast
syncline,
syncline, aadip
dip to
to the
the north
north is
is expected.
expected. This
is probably due
This deviation is
due to
flow folding
folding in the
ash—flow tuff
supplemental stop at
flow
the ash-flow
tuff (see
(see the
the supplemental
at the Marcellon
rhyolite for
for further
further discussion
discussion of
of flow
flow folding).
folding).
Stop 4B
4B —- Unit
Unit B
B
This stop is
is just to
to the
the west of an old stone fence (Fig.
(Fig. 24)
24) constructed
about 1900 as
about
as part of
of the
the old
old Driblow
Driblow farm.
farm.
Unit B is
is a
a porphyritic quartz,
quartz, plagioclase,
plagioclase, alkali feldspar—bearing
feldspar-bearing rhyo—
rhyolite with aa reddish—brown
reddish-brown to
to black
black matrix.
matrix. Quartz is
is rounded and
and clear and
and
may
may be
be up
up to
to 33 mm
mm in
in size.
size. Plagioclase is
is pink to
to white in
in color and
and occurs
in
in laths up
up to
to 66 mm
mm in
in size;
size; some
some grains
grains show
show prominent
prominent albite
albite twinning.
twinning.
Alkali
Alkali is
is difficult
difficult to
to identify
identify in
in hand
hand specimen.
specimen. On weathered surfaces
surfaces faint
faint
banding
banding and
and minor
minor brecciation
brecciation are
are observed.
observed. This quartz—bearing
quartz-bearing rock is
is distinguished from other quartz—bearing
quartz-bearing rhyolites in
in the
the Marquette inlier
inlier by its
its
higher
ratio.
higher Na20/K20
Na 0/K
ratio. Unit B is
is the
the only sodic rhyolite in
in the
the inlier
inlier
2
(Fig.
(Fig. 26).
26). Unit
ufiit B changes in
in lithology
lithology laterally.
laterally. On Ingalls
Ingalls Knob
Knob (south
(south of
of
Highway
Highway H)
H) quartz
quartz is
is small
small and
and rarely
rarely observed
observed in
in outcrop
outcrop whereas quartz
quartz is
is
large and
and easily identified
identified in
in unit
unit BB exposures
exposures to
to the
the north
north of
of HighwayH.
HighwayH.
°
The
The contact
contact between
between unit
unit BB and
and unit
unit C
C trends
trends No.
No. 10°
10° W. and
and passes
passes to
to the
the
south
south and
and east
east of
of this
this stop.
stop. Many
Many of
of the
the large
large blocks
blocks observed
observed just
just to
to the
the
south of our present position are breccias with an assortment of fragment
fragment types.
types.
It
It is
is doubtful,
doubtful, however,
however, whether
whether these
these blocks
blocks are
are in
in place.
place.
72
72
Stop 4C
4C —- Small
Small Andesite Dike Intruding
Intruding Unit C
C Rhyolite
Stop
Traverse due north
north from
from Stop
Stop 4B to
to the
the low
low outcrops
outcrops across
across the
the field
field in
in
the trees (just
(just to
to the
the north
north of
of ihe
the Bee
Bee Hives)
Hives) (Fig.
(Fig. 24).
24). At this
this stop
stop aa
fine—grained
unit C is
fine-grained variety of unit
is cut by a
a thin andesite dike (an
(an off—shoot
off-shoot
trending dike).
dike). The andesite
andesite and
and rhyolite
rhyolite are
are at
at first
first
of the main northeast trending
difficult
The following
difficult to
to distinguish
distinguish from
from one
one another
another in
in the
the field.
field.
following
characteristics will aid
aid in
in their
their identification.
identification. Unit C
C rhyolite
rhyolite breaks
breaks
irregularly
irregularly with
with aa splintery
splintery surface.
surface. Sparse small plagioclase laths
laths are
are the
the
dominant phenocryst.
,dominant
phenocryst. Jointing produces straight breaks and angular
angular corners
rock. The andesite contains small plagioclase laths (1/2
(1/2 mm)
mm) set in
in a
a
in the rock.
fine—grained
fine-grained matrix with
with aa characteristic
characteristic greenish
greenish hue.
hue. Jointing
Jointing produces
produces
irregular breaks and
and rounded corners
corners in
in the
the dike
dike rock.
rock. A
A fresh
fresh surface
surface of
of
the rhyolite reflects
when
reflects light
light from
from numerous
numerous planes,
planes, and
and thus
thus "twinkles't
"twinkles" when
rotated in
in direct
direct sunlight.
sunlight. Partially
Partially separated
separated splinters
splinters of
of rock
rock are
are lighter
lighter
in color than unbroken rock
rock and
and form
form grooves
grooves on
on the
the broken
broken surface.
surface. In concontrast,
trast, the andesite has aa smooth
smooth and
and dull
dull freshly
freshly exposed
exposed surface.
surface.
In several
several places,
places, aa very fine
fine banding is
observed in the
is observed
the andesite and
(N. 450
45° E.) obliquely to
to the
the strike
strike of
of the
the dike.
dike. These bands may
may be
be
trends (N.
flow bands sheared into
into this
this orientation
orientation after
after dike
dike emplacement.
emplacement. Alternately
they may reflect aa rock
rock cleavage
cleavage formed
formed during
during the
the folding
folding of
of these
these rocks.
rocks.
Stop 4D (Optional)
(Optional) —
- The Contact Between the
the Andesite Dike and
and Unit
Unit C
C
Rhyol
ite
Rhyolite
Since the
exposure is
small, it
will not
not be
be visited on the
the size of this
this exposure
is small,
it will
It is
is of
of considerable
considerable interest,
interest, however,
however, because
because it
it displays
displays one
one
field trip.
trip.
It
of the few exposed contacts
contaots in
in the
the inlier.
inlier.
east across
From Stop 2C walk to the east
across the
the field
field to the
the gap in the north—
northThe exposure
exposure (piled
trending fence
fence (Fig.
(Fig. 24).
24). The
(piled with rock)
rock) encountered on the
way is composed of
of unit
unit C
C rhyolite
rhyolite cut
cut by
by numerous
numerous quartz
quartz veins.
veins. After passpassing through
through the
ing
the gap in the fence proceed through
through the
the forest
forest (bearing
(bearing N.
N. 10
10 E.)
E.)
The contact
contact between rhyolite
rhyolite and
to the
the first
first rock
rock ledge.
ledge. The
and andesite is
is exposed
on top of
has toppled exposof this
this ledge where a
a juniper tree
tree with shallow roots
roots has
ing aa fresh
fresh rock
roák surface
surface (the
tree was
was uprooted
uprooted during
during aa major
major ice
ice storm
storm in
in
ing
(the tree
April, 1976).
1976). The intrusive contact trends
trends N.
N. 87°
87° E.
E. and
and dips
dips 60°
60° to
to the
the north.
north.
This dip
dip probably reflects
reflects the
northeast—trending normal
This
the inclination of
of a
a northeast-trending
normal
fault
fault (later
(later intruded
intruded by the
the dike)
dike) (Fig.
(Fig. 25).
25). The difference between rock
rock
types
types is subtle (see
(see discussion
discussion under
under Stop
Stop 4C).
4C). The contact is
is sharp;
sharp; no
no
are found
dike and
and no contact
contact effects
effects are
xenoliths of
of rhyolite
rhyolite are
found within the
the dike
in the
the rhyolite.
rhyolite. This dike is
is fine—grained
fine-grained and
and shows
shows little
little change
observed in
In thin
thin section,
section, the
in grain size from ôontact
in
contact to
to center.
center.
In
the texture of the
the
dike rock is intergranular to ophitic
of sausseritized plagio—
dike
ophitic with aa framework
framework of
plagioclase laths
clots set in aa patchy matrix of
epidote—clino—
clase
laths and clots
of iron oxide
oxide and
and epidote-clinozoisite. Both andesite and
and rhyolite
rhyolite are
are jointed
jointed with
with N.
N. 60°
60° E.
E. and
and N.
N. 40°
40° W.
W.
as
as important directions.
displays the contact
contact between the
dike and
Another exposure that displays
the andesite dike
unit C rhyolite can be reached by walking through the
the trees
trees from Stop 4C
(bearing N.
N. 10°
10° W.)
W.) to
to an
an exposure piled with rock (Fig.
(bearing
(Fig. 24).
24). The contact
here trends N.
N. 80 E. and
and dips
dips 65°
65° to
to the
the north.
north. Piled on top of the
the exposure
exposure
73
...,
are rocks
rocks moved
moved to
to this
this location
location from
from the
the cleared
cleared field
field to
to the
the north.
north. Most
Most of
of the
are
the
blocks
are
massive
unit
D
rhyolite.
This rock is similar in outward appearance
blocks
unit D rhyolite. This
to unit
unit C,
C, but
but it
it can
can be
be distinguished
distinguished quickly in the
field from the other fine—
to
the field
finegrained units
grained
units by the bell-like sound
sound emitted
emitted when
when hit
hit by
by aa hammer.
hammer.
Also the
rock breaks with aa distinctive "breaking
"breaking glass"
glass" sound.
sound.
Stop 4E —
Massive Unit
Unit D,
D, and Unit E
- Massive
See Figure 24 for directions from
See
from Stop
Stop 4D
4D to
to this
this locality.
locality.
at point 4E*
4E* (see
Fig. 24)
For orientation stand at
(see Fig.
24) and
and look to the northwest;
northwest;
the contact
contact between
between unit
unit D
D and
and unit
unit EE trends
trends N.
N. 30°
300 E.
E. through
through the
the grassgrass—
the
Unit E lies on the
covered depression before you.
you. Unit
the rock
rock ledge
ledge to
to the
the northwest.
northwest.
Massive unit
rhyolite is
fine grained near
near its
Massive
unit D rhyolite
is very fine
its contact with unit E,
E,
but becomes noticeably coarser in
in grain size to
to the
the south.
south. Plagioclase
altered to sausserite
sausserite occurs
occurs in glomeroporphyritic
glomeroporphyritic clots and
altered
and is the
the dominant
dominant
Phenocrysts are
set in a
devitrified matrix that
phenocryst. Phenocrysts
are set
a devitrified
that contains coarser—
coarsergrained pod—shaped
pod-shaped areas
areas (pumice
(pumice fragments?).
fragments?).
Broken spherulites are also
Unit D locally displays
displays fine
fine striations that
observed in
in the
the matrix.
matrix.
Unit
that are
similar to those in
in the
the andesite
andesite dike
dike (see
(see description
description of
of Stop
Stop 4D).
4D).
These
0
striations strike (N.
30°E.)
contact between units D
striations
(N. 30
E.) parallel
parallel to the
the contact
D and E but
dip obliquely to it
striations as
dip
it (80°
(80° south for
for the
the striations
as compared to 60°
60° north
for the
the contact).
Unit D at
at this
Unit
this location is
is similar in lithology to the
the fine—grained
fine-grained
variety of
of unit
unit C observed at
Stop 4C;
4C; it
however, splinters like glass
glass.when
at Stop
it however,
.. when
This fine-grained
broken and commonly rings
rings like
like aa bell
bell when
when hit
hit by
by aa hammer.
hammer.
has chemical
chemical characteristics
characteristics that
rock has
that distinguish it
it from other fine—grained
fine-grained
Marquette rhyolites (Fig.
(Fig. 26).
26).
Walk across
across the
the grass covered depression to
to the
the low
low rock
rock ledge
ledge of
of banded
banded
unit E rhyolite.
rhyolite. The contact between unit
unit D
D and unit
unit E trends
trends northeast
northeast
through this
this depression.
depression. Banding in
in unit
unit E is
is formed
formed by discontinuous white
to pink streaks
pumice fragments
fragments and
streaks that
that represent
represent pumice
and shards sheared and compressed during late—stage
late-stage primary flowage and
and during post—depositional
post-depositional compaction
compaction
and welding. Bands may be up to
to 50 cm long,
long, but are
are usually
usually less
less than
than 55 mm
mm in
in
width. Commonly they
they bend
bend about
about phenocrysts.
phenocrysts. Bands strike N.
N. 53°E.
53°E. and
and dip
47° to
to the
the west.
west.
On the
southwest corner of
of the
near the
On
the southwest
the outcrop near
the base of the
the unit,
unit, unit E
grades into
into aa spherulitic
spherulitic rhyolite.
rhyolite. Spheruites
Spherulites are
are as
as large
large as
as 33 cm
cm in
in
diameter.
diameter.
To the
the west,
west, the
the outcrops are
are covered by aa drumlin elongated in
in an
an east—
eastwest direction.
direction. This orientation reflects the
the movement of the
the Green Bay
Bay Lobe
Lobe
(Woodfordian)
(Woodfordian) from east
east to
to west
west in
in this
this area.
area.
Stop 4F
4F (Optional)
(Optional) —- Porphyritic
Porphyritic Unit DD
From
From Stop 4E walk north
north to
to the
the east—trending
east-trending fence,
fence, then
then follow
follow the
the fence
fence
eastward (300
(300 m)
m) to
to the
the north—south
north-south fence
fence (Fig.
(Fig. 24).
24). Outcrops encountered to
to
the
east—trending fence
fence are
are of
of unit
the north
north of the
the east-trending
unit E rhyolite,
rhyolite, blocks in the field
field
74
74
to
to the
the south
south are
are fine—grained
fine-grained unit
unit DD rhyolite.
rhyolite. Continue
Continue walking
walking
Note
the
angular
blocks
fence to
to the
the first
first exposure.
exposure. Note the angular blocks of
of rock
rock to
to
fence
of the
the fence.
fence. Here aa wide
wide assortment
assortment of
of rhyolite
rhyolite lithologies
lithologies is
is
of
blocks
blocks were
were probably
probably transported
transported by
by ice
ice aa short
short distance.
distance.
along
along the
the
the
the north
north
found.
found. These
These
Unit
Unit DD is
is gray
gray on
on weathered
weathered surfaces
surfaces but
but pink
pink on
on freshly
freshly broken
broken fractures.
fractures.
In
In hand specimen abundant
abundant phenocrysts of rounded quartz up
up to
to 3
3 mm in
in size
size and
and
subhedral feldspar (plagioclase
and
alkali
feldspar)
up
to
5
mm
in
length
(plagioclase
feldspar) up to
in length are
are
-easily identified.
identified. In
In thin section the rock contains large
large rounded
rounded and
and embayembayeasi1y
ed quartz (10%),
(10%), subhedral grains of sausseritized plagioclase (8%),
(8%), and
and ortho—
orthoperthitic texture
texture (14%).
(14%). Banding in
in unit D
D at
at this
this locality
locality is
is
clase with perthitic
faint;
faint; band trends
trends vary
vary from
from N.
N. 7°
7° E.,
E., 70°
70° east
east to
to N.
N. 500
50° E,
E, 85°
85° southeast
southeast
(deviation due to
to flow
flow folding?).
folding?).
(deviation
Unit D
D is
is easily distinquished from unit B,
B, particularly by differences
in Na20/K20 ratio (the
greater than 11 for
for unit
(the ratio is
is greater
unit B and
and less
less than 1 for
unit D).
D). Also,
Also, unit D
D contains a 100 m
m thick
thick massive phase (stop
(stop 4E);
4E); aa
unit
similar
similar massive phase
phase is
is not
not associated
associated with
with unit
unit BB (or
(or in
in fact
fact with
with unit
unit F,
F,
the other quartz,
plagioclase, alkali
alkali feldspar—bearing
feldspar-bearing rhyolite
rhyolite unit).
unit).
the
quartz, plagioclase,
75
75
SUPPLEMENTAL STOP
STOP -- MARQUETTE
MARQUETTE RHYOLITE
RHYOLITE ON
ON INGALL'S
KNOB
SUPPLEMENTAL
INGALL'S KNOB
Highlights of
of this
this stop
stop include
include the
the well-banded
well—banded unit
unit C,
C, and
and pumice
pumice
Highlights
lenses and
and breccia in
lenses
in unit
unit A.
A.
Unit C —
Banding: Park
Park at
at the
the entrance
entrance to
to the
the Ingall's
Knob gravel
gravel pit
pit (see
Unit
- Banding:
Ingall's Knob
(see
Fig. 24).
Walk along
along the
the dirt
dirt road
road toward
toward the
the gravel
gravel pit
pit and
and then
then bear
bear right
right
Fig.
24). Walk
(south) to
to the
the outcrops
outcrops of
of dark rhyolite clearly visible
(south)
visible on
on the
the flanks
flanks of
of
Ingall's Knob. These
These outcrops
outcrops are
are composed
composed of
of well
well banded
banded unit
unit C
C rhyolite
rhyolite
Ingall's
(Fig. 27) •
(Fig.
Figure
Figure 27.
27.
Photomicrograph of highly
highly flattened
flattened and
and crenulated
crenulated shards
shards in
in the.
the.
Marquette rhyolite
rhyolite (unit
(unit C).
C). Flattening probably occurred during
during
primary movement of the
Folding may have occurred during
the ash
ash flow.
flow.
during
flowage or during
during later
later deformation.
deformation. Bar scale
scale is
is 11 mm
mm long.
long.
The bands are discontinuous and are formed by sheared and collapsed pumice
fragments.
Banding strikes
strikes N.
N. 50°E.
50 0 E. and dips 700
70° to
to 800
80° to the
the south;
south; bands
are locally
folded.
The
rock
in
this
locality
also
contains
lenses
of breccia
locally folded.
in this
and spherulitic
spherulitic rhyolite.
rhyolite.
Unit AA —- Fiamme
Fiamme (Pumice Lenses):
Lenses): Walk
Walk to
to the
the end
end of
of Ingall's
Ingall's Knob
Knob (see
(see Fig.
Fig.
24)
24) and
and climb directly
directly up
up the
the rock
rock face.
face. The
The rock
rock forming
forming the
the bluff
bluff on
on the
the
southeast end of Ingall's
Knob
is
a
porphyritic
quartz,
orthoclase,
plagio—
Ingall's
is
quartz, orthoclase, plagioclase—bearing
ash—flow tuff
tuff showing
showing nicely
nicely developed
developed fiamme
fiamme (the
black
clase-bearing rhyolite
rhyolite ash-flow
(the black
lens—like
features
in
the
rock).
The
fiamme
are
collapsed
pumice
fragments
lens-like features in the rock). The fiamme are collapsed pumice fragments
and
and are
are elongated
elongated parallel
parallel to
to the
the strike
strike of
of unit
unit AA (N.
(N. 50°E.).
50 0 E.). They
They have
have an
an
average
average axial
axial ratio
ratio of
of 12
12 ++ 8/1
8/1 (based
(based on
on the
the measurement
measurement of
of 50
50 fiamme).
fiamme).
In thin section,
section, unit A
A rhyolite
rhyolite contains
contains rounded
rounded and
and embayed
embayed quartz
quartz
(10%),
alkali
feldspar
with
perthitic
(10%),
feldspar
perthitic texture
texture (8%),
(8%), partially
partially sausseritized
sausseritized
76
76
plagioclase
and iron
plagioclase (5%),
(5%)"and
iron oxide
oxide (tr).
(tr). The
The matrix
matrix is
is finely
finely devitrified
devitrified but
but
contains bands
bands that
that are
are more
more coarsely
coarsely recrystallized.
recrystallized. Flow
Flow texture
texture is
is common
common
contains
with
with shard—like
shard-like forms
forms aligned
aligned and
and locally
locally bent
bent about
about phenocrysts
phenocrysts of
of quartz
quartz
Ic xenolith
xenolith was
was identified in
and feldspar
feldspar (Fig.
(Fig. 28).
28). One
One small
small maf
mafic
in thin
thin
and
sections.
sections.
Figure 28.
28.
Figure
flattened shards
shards in the Marquette rhyolite
Photomicrograph of flattened
rhyolite
ash-flow tuff
tuff (unit
(unit A).
A). Shards are
are aligned and locally
ash—flow
locally bent
bent about
about
quartz and
and feldspar.
feldspar. Bar scale is
phenocrysts of quartz
is 11 mm
mm long.
long.
The change in slope above the rock face
face marks the contact
Unit A
A —- Breccia: The
between the top of unit
unit A ash—flow
ash-flow tuff
tuff (below)
(below) and
and the base of unit A
A breccia
o
contact
varies
in
orientation
between
N.
40°E.
and
N.
30°W.,
(above).
This
in
orientation
between
N.
40
E.
and
N.
30 o W.,
(above).
o
The wavy nature of this
trends N.
N. 50°E.
50 E. The
this contact suggests that
that
but in general trends
it
is
an
unconformity.
it is
It is
Unit
is poorly sorted and
and is
is approximately
approximately 50
50 mm thick.
thick.
It
is
Unit A breccia is
o
50°E.
banded with large clasts and
crudely banded
and matrix
matrix fragments
fragments elongated
elongated in
in aa N.
N. 50
E.
Along the
the route of this
direction
(parallel to the
the strike of
of unit
unit A).
A). Along
this traverse,
traverse,
direction (parallel
concentrated toward
toward the
aa crude
is observed with large fragments concentrated
the
crude size
size sorting
sorting is
This size
size sorting,
sorting, however,
however, is
is not
not characteristic
characteristic of
of
upper part of the
the unit.
unit. This
In
other
locations,
large
of
rhyolite
are
the
unit
as
a
whole.
In
other
locations,
large
fragments
rhyolite
are
the unit
On our
our route,
route, breccia
breccia near
near the
the base
base of
of the
the unit
unit
found
the unit.
unit.
On
found throughout the
contains
(less than
contains small
small (less
than 30
30 cm
cm in
in size)
size) dark-colored
dark—colored porphyritic
porphyritic rhyolite
rhyolite
Toward
fragments.
are quartz—bearing
quartz-bearing rhyolites.
rhyolites. Toward
Only aa few
few of
of the
the fragments
fragments are
fragments. Only
the top
top of
of the
the unit
unit the
the fragments
fragments become
become huge;
huge; one
one block
block is
is 33
33 m
m long
long in
in aa
the
o
Most of
of the
the larger
larger fragments
fragments are
E. direction and is
is 12 m
m wide. Most
are similar
N.
N. 50
50°E.
However,
three
in
lithology
to
the
quartz-bearing
unit
A
ash-flow
tuff.
However,
three other
in lithology to the quartz—bearing unit
ash—flow tuff.
rock types
types are
are present;l)banded
present;.l)banded rhyolite
rhyolite with
with small
small white
white feldspar,
feldspar, 2)
2) banded
banded
rock
rhyolite with
with large
large (5mm)
(5mm) white
white feldspar,
feldspar, and
and 3)
3) massive
massive rhyolite
rhyolite with
with small
small
rhyolite
The matrix
matrix of
of the
the breccia
breccia is
is gray
gray in
in
quartz
phenocrysts. The
quartz and
and alkali
alkali feldspar
feldspar phenocrysts.
77
77
------------------------------------------...,
color on
on weathered
weathered
color
with
crystal,
rock
with crystal, rock
surfaces.
In thin
thin section
section the
the matrix
matrix is
is microbrecciated
microbreccjated
surfaces.
In
o
and angular
angular shard
shard fragments
fragments aligned
aligned in
in the
the N.
and
E. direction.
N. 50
50°E.
direction.
Breccia Exposure
Exposure at
at the
the Summit
Summit of
of Ingall's
Knob: Details
Breccia
Ingall's Knob:
Details of
of the
the relationship
relationship
between
fragments
and
matrix
are
revealed
in
an exposure
between fragments and matrix are revealed in an
exposure at
at the
the summit
summit of
of
Ingall's Knob
Knob (Fig.
The largest
largest fragment
fragment at
at this
this location
location is
is aa porphyporphy—
Ingall's
(Fig. 29).
29). The
ritic (black
(black in
in color)
color) rhyolite
rhyolite composed
composed of
of quartz
quartz and
and alkali
alkali feldspar
feldspar phenoritic
pheno—
o
crysts.
It
is
5
in
wide
and over
over 10
10 m
m long
long in
in the
the N.
N. 50
50°E.
direction. Contacts
crysts.
It is 5 m wide and
E. direction.
Contacts
between it
it and
and the
the breccia matrix (gray
between
(gray in
in color) are
are sharp.
sharp. Note
Note the
the smaller
fragments of
of black
black rhyolite
rhyolite in
in the
the matrix
matrix on
on both
both sides
sides of
of the
the larger
fragments
larger blackblack—
colored rhyolite
rhyolite fragment.
colored
fragment.
These
These fragments
fragments probably
probably are
are pieces
pieces of
of rhyolite
rhyolite
that broke
broke off
off the
the larger
larger fragment
fragment during
during transport.
that
transport.
Just
Just to
to the
the north
north there
is
a
large
red
fragment
impregnated
is a large red fragment impregnated with quartz veins.
veins. The
fragThe size
size of
of this
this fragment is
is difficult
difficult to estimate because of extensive cover.
ment
cover. Notice
Notice the
the smaller
smaller
red—colored fragments
fragments in
in the
the matrix
matrix just
just to
to the
the south
south of
of the
the red
red-colored
red clast.
clast. The
The
red fragment
fragment is
is aa porphyritic
porphyritic rhyolite
rhyolite similar
similar in
in mineralogy
mineralogy to
red
to the
the black
black
fragments. Both
Both fragment
fragment types
are similar
similar in mineralogy to
to the
unit A ashfragments.
types are
the unit
ash—
flow tuff.
flow
tuff.
Origin of
Origin
of the
the Breccia:
Breccia:
In
this breccia in
in the
the
In order
order to
to explain
explain the origin of this
following observations
observations must be accounted for:
following
for:
1.
The matrix
matrix of
of the
the breccia
breccia may
may show a
crude layering that
1.
The
a crude
that resembles
resembles
a
flowage
a flowage texture.
texture. Smaller
and shards
aligned in the
the
Smaller fragments,
fragments, crystals
crystals and
shards are
are aligned
N. 50°E.
N.
50 o E. direction.
direction.
Many of
of the
the larger clasts have unequal dimensions in
in section
and have
have
section and
their long axes oriented in
in the
the N.
N. 50°E.
50 o E. direction.
direction.
2.
2.
There are
are aa wide variety
variety of
of clast
clast types.
types. Many of the
the larger
larger fragfragments are
are similar in
in lithology to
to the unit A
A ash—flow
ash-flow tuff.
tuff.
3.
3.
4.
4.
There is
is only a
a slight suggestion of size sorting in
in the
the deposit.
deposit.
5.
5.
Many of
of the
the fragments
fragments are
are very
very large
large (up
(up to
to 33
33 mm long).
long).
The unit
unit is
is similar
similar in
in overall
overall fabric
fabric to
to mud—flow
mud-flow breccias or
or lahars
lahars
commonly
tuffs and lavas in
commonly interbedded
interbedded with
with ash—fLow
ash-flow tuffs
in Tertiary
Tertiary and
and Holocene
Holocene
volcanic
volcanic piles,
piles, in
in terms
terms of
of poor
poor sorting
sorting and
and fragment
fragment size
size (Parsons,
(Parsons, 1968;
1968;
Smith,
Smith, 197Gb).
1976b). However,
However, mud—flow
mud-flow breccias
breccias usually
usually do
do not
not contain
contain elongated
elongated
or
or oriented
oriented fragments,
fragments, and
and the
the matrix does not show
show flow
flow structure.
structure. The
The
unit
unit may
may instead
instead represent
represent aa pyroclastic—flow
pyroclastic-flow breccia
breccia (that
(that is,
is, aa block
block avalavalanche
anche or
or block—flow
block-flow deposit).
deposit). Modern
Modern examples
examples of
of this
this type
type of
of deposit
deposit are
are
described
described by
by Aramaki
Aramaki (1963)
(1963) and
and Parsons
Parsons (1968)
(1968) from
from Asama
Asama Volcano
Volcano in
in Japan.
Japan.
Modern
Modern block—flow
block-flow deposits
deposits may
may erupt
erupt initially
initially as
as ash
ash flows
flows and
and then
then during
during
emplacement
emplacement may
may pick
pick up
up large
large fragments
fragments from
from the
the surface
surface over
over which
which they
they
travel.
travel. Also,
Also, fragments
fragments from
from the
the walls
walls of
of the
the vent
vent and
and cognate
cognate pumice
pumice are
are
often
often incorporated.
incorporated. The
The matrix
matrix of
of the
the Holocene
Holocene block—flow
block-flow deposits
deposits around
around
Asama
Asama Volcano
Volcano may
may be
be crudely
crudely banded
banded and
and is
is commonly
commonly composed
composed of
of fine
fine ash
ash and
and
dust.
dust. These
These breccia
breccia units
units extend
extend as
as far
far as
as 18
18 km
km from
from Asama
Asama Volcano
Volcano and
and vary
vary
in
in thickness
thickness from
from 40
40 cm
cm to
to 10
10 mm (Parsons,
(Parsons, 1968).
1968).
There
There are
are many
many similarities
similarities between
between the
the Holocene
Holocene pyroclastic—flow
pyroclastic-flow breccias
breccias
about
about Asama
Asama Volcano
Volcano and
and the
the unit
unit AA breccia;
breccia; consequently,
consequently, II suggest
suggest that
that the
the
78
78
Matrix
Matrix
NN
0
:
o
\/
I—
Ii
Cover
Cover
quartz veins
veins
quartz
k~~v~:'~>:"?
_
~~
~
\N?
.
/"
'.
. ~/
. .,; 0
—
o()
oO
00
o
"" \
"
-
0
0
-
/
"",
?...
'"
.......""
",......... ---/
00
—7-Matrix oo~
~ 7
7- --~/
Matrix
\
"
I
- /
\ '
./ ./,r-.
-~/~.
/. -=- /.
.........
-::: . :
\ -
/
.r
-.
?
•
~
?:;:~/- \
~
°/....-- / ......
•
?/
/
C/.
ct:1/.· .
7/ '
/
110
T
Tree
Tree
feet _I
00
0
00
00
.
?"- - ? /1' / ..
• _ . Tree
?"2?
ree 7' ..
Matrix
Matrix
Stump
EXPLANATION
fH
Black
r::I
Red
Red rhyolite
rhyolite
rhyolite
Small
of rrhyolite
Sma
II ffragments
rag men t s of
hy 0 lit e
in
matr ix
in matrix
o11
Figure
Figure 29.
29.
Matrix,
microbreccia
Matrix, microbreccia
Sketch map
map of
of an
an exposure
exposure of
of unit
unit A breccia
Sketch
breccia on Ingall's
Ingall's Knob.
Knob.
79
79
unit A
A breccia
breccia is
is aa pyroclasticpyroclastic— or
or block-flow
block—flow breccia
breccia and
and not
not aa mud-flow
mud—flow
unit
deposit.
deposit.
Unit A-Unit
A—Unit B Contact
Unit
The contact
contact between
between unit
unit A
A and
and unit
unit B
B on
on Ingall's
Ingall's Knob
Knob is
is gradational.
gradational.
The
The basal
basal part
part of
of unit
unit B
B contains
contains numerous
numerous beds
beds and
and lenses
lenses of
of breccia
breccia that
that
The
grade into unit A
Just to
to the
the northwest
northwest of
of the
the outcrop
outcrop of
of unit
unit A
grade
A breccia. Just
detail above)
good exposure
exposure of brecciated unit
breccia (described
(described in detail
above) is
is a
a good
This lens
of breccia is
separated from
from massive
massive unit B by a
B (Fig.
(Fig. 24).
24). This
lens of
is separated
a thin
(2 m
m wide)
wide) sheared zone.
Unit B breccia at
(2
zone.
Unit
at this
this exposure is
is monomictic.
monomictic.
This is
contrast to other
other unit
lenses, and
This
is in contrast
unit B breccia lenses,
and the
the unit A breccias
that are
are polymictic.
that
80
80
N
WATE RTOWN
WATERTOWN
t+
IUNCTION
TO
WATERLOO
STOP 5 -
POLISHED
EXPOSURE
NORTH
QUARRY
SOUTH QUARRY
SOUTH
QUARRY
UW
DRILLIN
DRILLING
SITE
.5 MILES
0
CONTOUR INTERVAL
CONTOUR
INTERVAL
10 FEET
10
FEET
EXPLANATION
—
====ROAD
ROAD
•
BUILDING
BUILDING
QUARRYWALL
WALL
JVQUARRY
Figure
Figure 30.
30.
Detailed map of the Portland
Portland Quarries.
Quarries. Field trip Stop 55 is
is in
in the
the
north quarry.
quarry. South quarry should
should be
be entered
entered from
from the
the east.
east.
82
82
QUARTZ ITE NEAR
NEAR PORTLAND
PORTLAND
STOP 5 -- WATERLOO QUARTZITE
This stop illustrates
quartzite, the
This
illustrates the
the lithology of the
the Waterloo quartzite,
the youngest major Precambrian rock
est
rock unit
unit in
in south—central
south-central Wisconsin.
Wisconsin. These outcrops
are at
at the
the extreme
extreme southeastern
southeastern edge
edge of
of the
the exposed
exposed Precambrian
Precambrian shield
shield in
in
are
Wisconsin.
gate on the
19, walk south
Location:
From the
the locked gate
the south side
side of
of S.T.H.
S.T.H. 19,
toward
~oward the
the John
John O'Laughlin
O'Laughlin Quarries
Quarries (this
(this area
areaisis-a
-a Department
Department of
of Natural
Natural
Resources hunting
hunting preserve).
preserve). At the
the road
road junction
junction take
take the
the left
left fork.
fork. The
right
of the
Wisconsin's two deep drill
drill
right fork leads
leads to the
the site
site of
the University of Wisconsin's
holes, about 900 feet of
holes,
of core
core was
was obtained
obtained from
from one
one of
of them.
them. Drilling was
terminated
before intersecting the
base of
quartzite (see
Haimson, guide
terminated before
the base
of the
the quartzite
(see Haimson,
Walk
past
the
large
corrugated
iron
building
and
then
turn
1978).
the large
iron
and then turn west (right)
(right)
1978).
and walk
walk about
about 70 m
m through the
and
the trees
trees to
to the
the quarry
quarry (see
(see Fig.
Fig. 30
30 for
for route).
route).
The Waterloo Quartzite is
Introduction:
The
is probably stratigraphically equivalent
to the
the Baraboo
Baraboo and
and Barron
Barron Quartzites
Quartzites in
in Wisconsin
Wisconsin and
and to
to the
the Sioux
Sioux Quartzite
Quartzite
to
In
south—central
in Minnesota
Minnesota and South Dakota (Dott
in
(Dott and
and Dalziel,
Dalziel, 1972).
1972).
In south-central
Wisconsin the quartzite
quartzite sheet lies
lies stratigraphically above late—Penokean
late-Penokean
aged rhyolites
rhyolites and
and granites
granites and
and is
is mainly
mainly preserved
preserved as
as infolds
infolds into the
aged
the igneigneThe absolute age
ous basement.
basement. The
age of the quartzite can only be determined by
indirect means. At Baraboo
Baraboo the
the quartzite overlies
overlies rhyolites
rhyolites that
that are
are similar
similar
in
chemistry
to
those
rocks
in
the
Fox
River
Valley
dated
at
1765
m.y.
in
in the Fox River Valley dated at 1765 m.y. old.
old.
This date is
This
is the
the maximum
maximum age
age of
of the
the quartzite.
quartzite. Both the rhyolite and overlying quartzite
quartzite were
were deformed
deformed during an event suggested by Smith (1978a)
(1978a) to
to
Rb—Sr apparent age of the
have occurred 1650
1650 m.y. ago.
ago. This date is the Rb-Sr
the Fox
River Valley igneous
igneous rocks
rocks (Van
(Van Schmus
Schmus and
and others,
others, 1975).
1975). These data suggest
suggest
that
Baraboo—Waterloo Quartzite was
was deposited on an eroded rhyolite—granite
that the
the Baraboo-Waterloo
rhyolite-granite
basement between 1765
1765 and
and 1650
1650 m.y.
m.y. ago.
ago. A pegmatite dike with
with coarse
coarse quartz,
quartz,
feldspar and
muscovite crystals
crystals that
feldspar
and muscovite
that cuts the Waterloo Quartzite (on
(on Rocky
T. 9N.,
R. l3E.)
has been dated at 1440 m.y.
Island —- NW
Sec. 27,
27, T.
9N., R.
l3E.) has
m.y. old by
the
Rb—Sr method (Aldrich
Also, muscovite from a phyllite
the Rb-Sr
(Aldrich and
and others,
others, 1959).
1959). Also,
bed in the
Quartzite has
has been dated
dated at
m.y. old by the K—Ar
bed
the Waterloo Quartzite
at 1410 m.y.
K-Ar
technique (Goldich
dates place a
(Goldich and
and others,
others, 1966).
1966). These dates
a minimum age on the
the
deposition of
of the
the quartzite.
quartzite.
,
t,
At Waterloo,
Waterloo, the
the dominant rock
rock is a
a red to
to gray vitreous
vitreous quartzite comcomposed
of
75
to
98%
Si02.
Quartz
is
present
as
interlocking
posed
to 98% Si02'
is
interlocking and
and strained
strained
sand—sized grains (Fig.
sand-sized
(Fig. 31).
31). Muscovite in
in the
the matrix of the
the quartzite commoncommonly displays
displays lepidoblastic
lepidoblastic texture,
with increasing amounts
ly
texture, and
and with
amounts of mica the
Occasionally, thin phyllite layers
rock may grade into aa foliated
foliated quartzite.
quartzite.
Occasionally,
are found
found interbedded with the
Bands of
are
the quartzite.
quartzite. Bands
of andalusite
andalusite schist were
identified
in core
core recovered
recovered from
from the
the deep
deep well
well drilled
drilled just to the
identified in
the east of
the quarries
quarries (Haiinson,
(Haimson, 1978). The andalusite is
is partially
partially altered
altered to
to sericite.
sericite.
The assemblage andalusite—muscovite—quartz
andalusite-muscovite-quartz suggests that
that the
the quartzite was
locally, if
not regionally,
regionally, metamorphosed
metamorphosed to the
part of the
locally,
if not
the upper
upper part
the greenschist
facies. An amphibolite dike was also encountered in
in the
the well (Haimson,
(Haimson, 1978).
1978).
In the
the Waterloo
Waterloo area
area the
the quartzite
quartzite forms
forms aa broad
broad east-plunging
east—plunging syncline
syncline
In
(Buell, 1892,
1892, Warner,
Warner, 1904,
1904, Sumner,
Sumner, 1956)
1956) which
which is
is almost
almost entirely
entirely buried
buried
(Buell,
by Ordovician and
and Cambrian sedimentary
sedimentary rocks
rocks (Fig.
(Fig. 32).
32). Outcrops to
to the
the
north of
-h-, Sec. 25,
T. 8N.,
8N., R.
R. l3E.)
define the
north
of Lake
LakeMills
Mills(NE(NE
25, T.
l3E.) define
the south limb
of the structure.
structure. Here bedding dips
dips to
to the
the north
north at
at 500.
50°. The apparent nose
t,
83
of the
of
the fold
fold is in the Portland area
area (the
(the area
area of
of Stop
Stop 5).
5). Here the strike
o
of
bedding
changes
from
N.
30°W.
(in the
the south)
south) to N.
N. 30°E.
of bedding
from N. 30 W.
(in
30 o E. (in
(in the
the north)
north)
defining a
a broad concave eastward arc;
arc; the
the nose
nose of
of the
the syncline.
syncline.
Strike
and dip
dip measurements
measurements are
are a
bit erratic
erratic in this
area suggesting that
and
a bit
this area
that the
the
structure in the nose of
the
syncline
is
complex.
The north limb of
of the syncline is complex. The
of the
the syn—
syndine is
cline
is exposed
exposed near
near Mud
Mud Lake
Lake where
where quartzite
quartzite strikes
strikes N.
N. 80°E.
80 o E. and
and dips
dips
The north
north limb
limb may
may extend
extend as
as far
far to the
east as
steeply to the
the south.
south. The
the east
as Hartford in Washington County (Sumner,
ford
(Sumner, 1956).
1956).
Figure
Figure 31.
31.
Photomicrograph of
of the
the Waterloo
Waterloo Quartzite
Quartzite from
from the
Photomicrograph
the Portland Quarry.
Quarry.
Interlocking and strained quartz grains
grains are
are interrupted
interrupted by aligned
laths of
laths
of muscovite.
muscovite. With increasing
increasing amounts of muscovite the
the rock
rock
grades into
into aa foliated
foliated quartzite
quartzite and
and finally
finally aa phyllite or schist.
grades
Bar scale
scale is
is 11 mm
mm long.
long.
The quartzite at
at Waterloo is well jointed
jointed with N.
N. 40°E.
40 o E. and N.
N. 80°E.
80 o E.
o
directions common (also
(also N.
N. 70°W.
70 W. as
as aa minor
minor direction).
direction). However no
no detailed
studies of
of the rock fabric in
studies
in the
the Waterloo
Waterloo area
area have
have been
been undertaken.
undertaken. Thick
Thick
layers of
of phyllite,
layers
phyllite, so common in
in the
the upper
upper part
part of
of the
the Baraboo
Baraboo Quartzite,
Quartzite,
are lacking in the Waterloo Quartzite. Phyllite beds at Waterloo are thin
are
thin
(rarely thicker
thicker than
than 25
25 cm)
cm) and
and commonly
commonly pinch
pinch out
out over
over aa lateral
lateral distance
distance
(rarely
of 10 to
to 20
20 m.
m. Primary structures such as bedding planes,
planes, cross bedding and
and
conglomerate beds are common,
common, and ripple marks are occasionally observed.
observed.
The unravelling of the structural history of the Waterloo Quartzite is
is crucial
to the understanding
understanding of
of the
the 1650
1650 m.y.
m.y. old
old event.
event.
The Waterloo
Waterloo Quartzite
Quartzite is
is overlain
overlain by
by Cambrian
Cambrian sandstones
sandstones that
that locally
locally
contain large
large rounded
rounded boulders
boulders of
of quartzite.
quartzite. About 3 km north
north of
of Stop
Stop 55 (Fig.
(Fig.
32),
32), blocks of quartzite 1 meter in size are embedded in Cambrian sandstone
sandstone
close to the quartzite exposures;
exposures; the size of the
the clasts decreases rapidly
until just 700 m
m from the
the sandstone—quartzite
sandstone-quartzite contact the
the Cambrian sandstone
is
fine grained and friable and
is fine
and contains
contains no
no quartzite
quartzite fragments
fragments (Buell,
(Buell, 1892).
1892).
84
84
PORTLA D
SHIELDS
19} - . . - - - - - - l
1
WATERTOWN
o
2 MILES
WATERLOO
N
MILFORD
t
EXPLANATION
E X P L A N AT I ON
o0
QUARTZITE
QUARTZITE
EXPOSURE
EXPOSURE
DIP OF
OF BEDDING
AND DIP
BEDDING
STRIKE
STRIKE AND
-®—i--— f
-.-...;:)~
H.R.
H.R.
ROAD
ROAD
RAILROAD
TRACK
RAILROAD TRACK
FIELD
ROUTE
TRIP ROUTE
FIELD TRIP
HUBBLE
TON
HUBBLETON
ROAD
ROAD
Stop 55
Figure
Detailed route
route map
map through
through the
the Waterloo
Waterloo Quartzite
Quartzite area.
area. Stop
Figure 32.
32. Detailed
Map adapted
adapted from
from Buell
Buell (1892).
(1892).
is
is at
at the
the Portland
Portland Quarries.
Quarries. Map
85
85
If the
the Paleozoic
Paleozoic sedimentary
sedimentary rocks
rocks and
and the
the Pleistocene
Pleistocene sediments
If
sediments were
were
stripped
from
the
Waterloo
area,
the
quartzite
would
stripped from the Waterloo area, the quartzite would stand
stand as
as an
an arcuate
arcuate
ridge (concave
(concave to
to the
the east)
east) 500
500 to
to 900
900 feet
feet above
above the
ridge
the surrounding
surrounding Precambrian
Precambrian
surface.
For
example,
to
the
north
of
the
city
of Waterloo,
Waterloo, quartzite
surface. For example, to the north of the
quartzite is
is
intersected in
in deep
deep wells
wells at
at 135
135 feet
feet above
above sea
intersected
sea level.
level. Just
Just 22 miles
miles to
to the
the
east, quartzite
quartzite is
is exposed
exposed at
at the
the Portland
Portland quarries
quarries at
east,
at an
an elevation
elevation of
of 860
860
feet (see
(see Smith,
Smith, 1978c).
l978c).
feet
Only one
one deep
deep well
well has
has penetrated
penetrated quartzite.
quartzite. This
Only
This well
well located
located near
near
Reesville
in
western
Dodge
County
penetrated
500 feet
feet of
of quartzite
Reesville in western Dodge County penetrated 500
quartzite before
before
entering aa mica-rich
mica—rich rock described by Thwaites (1940)
entering
(1940) as
as aa gneiss
gneiss or
or aa
schistose
quartzite.
schistose quartzite.
Studies of
of well
well cuttings
cuttings show
show that
that the
the Waterloo
Waterloo Quartzite
Quartzite is
Studies
is part
part of
of aa
large
area
of
quartzite
extending
from
Waterloo
to
Milwaukee
large area of quartzite extending from Waterloo to Milwaukee and
and north
north to
to
Fond du
du Lac
Lac (Smith,
Fond
(Smith, l978c).
1978c). Thwaites
Thwaites (1940)
(1940) reported
reported iron-bearing
iron—bearing shale
shale
interbedded
with
this large quartzite sheet.
interbedded with this
sheet.
Stop Description:
Description: After
Stop
its steep south
wall.
After entering
entering the
the quarry,
quarry, walk to its
south wall.
The
rock
this quarry
quarry is
typical of
of Waterloo
Waterloo Quartzite
Quartzite in
The rock in
in this
is typical
area.
in the
the Portland area.
It is
is coarsely
coarsely recrystallized and is
It
is rich in
in muscovite.
muscovite. Bands
Bands of conglomerate
are common and
and contain quartzite
quartzite fragments
fragments up
up to
to 33 cm in
are
in size.
size. Conglomerate
Conglomerate
bands
strike
N.
35°E.
and
dip
42°
to
the
south.
bands
N. 35°E. and
42° to the south.
On the western part of
of the
the
quarry wall a 25 cm thick
thick phyllite
phyllite lens
lens is
is exposed
exposed (Fig.
(Fig. 33).
33). The
phyllite
The phyllite
thins
thins to
to 3
3 cm
cm and
and eventually
eventually pinches
pinches out
out to
to the
the west. Color banding that
that
represents
primary
bedding
parallels
conglomerate
represents
parallels conglomerate layers.
layers. Cross
is
Cross bedding
bedding is
observed just above the
the phyllite lens
lens (Fig.
(Fig. 33).
33). Dott and Dalziel (1972)
(1972)
report
report a
a mean current direction of
of 165
165 degrees
degrees (S.
(S. l5°E.)
15°E.) for
for the Waterloo
Quartzite
based
on
measurements
of
38
Quartzite based on measurements of 38 cross sets.
sets. This compares with aa
direction of 171 degrees measured for the Baraboo Quartzite
Quartzite (Dott
(Dott and
and Dalziel,
Dalziel,
1972).
1972). Common current directions for these two quartzites strongly
strongly suggest
suggest
that
that the
the Baraboo
Baraboo and
and Waterloo
Waterloo Quartzites
Quartzites are correlative.
correlative.
In
In outcrops just to the
the south
south of
of the
the quarry,
quarry, foliated
foliated quartzite
quartzite is
is
highly
polished
and
grooved
(due
to
highly polished and grooved (due to glaciation).
glaciation). Grooves
Grooves trend
trend N.
N. 20°E.
20 o E.
Foliation
Foliation and
and cross
cross bedding
bedding (?)
(?) impart
impart aa swirl—like
swirl-like pattern
pattern to
to the
the outcrop.
outcrop.
In
places
the
foliatedquartzite
In places the foliated quartzite has
has weathered
weathered out in
in aa series
series of
of low
low ridges
ridges
each
each about
about 11 cm
cm high
high (Fig.
(Fig. 34).
34).
86
86
Figure 33.
33.
Figure
View of aa thin
thin phyllite
phyllite layer
layer (between
(between arrows)
arrows) interbedded
interbedded with
with
quartzite at
at the
the Portland
Portland Quarry
Quarry (Stop
(Stop 5).
5). Note
Note the
the crossbedding
crossbedding
in the quartzite just
just above
above the
the phyllite
phyllite bed.
bed.
Figure
Figure 34.
34.
located just
just to
to the
the
Close-up
Close—up view
view of
of foliated
foliated Waterloo
Waterloo Quartzite
Quartzite located
Foliation planes
planes are
are
south
south of
of the
the quarry
quarry visited
visited at
at Stop
Stop 5.
5. Foliation
each about
about 11 cm
cm high.
high.
weathering out
out here
here into
into aa series
series of
of low
low steps
steps each
weathering
87
87
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89
1 000-3K8T007-78
1000-3K8T007
-78
OMISSIONS
OMISSIONS
South-Central Wisconsin
Wisconsin
Precambrian Inliers
Field
Field Trip
Trip Guide
Guide Book
Book Number
Number 22 -- Precambrian
Inliers in
in South-Central
off the
bar scales
In preparation
publication, the
the bar
scales were
were inadvertently
inadvertently left
left off the
In
preparation for
for publication,
following figures.
figures.
Figure 14
14 (p.
(p. 59)
59)
Photomicrograph
Marcellon rhyolite
Photomicrograph of
of Marcel10n
ash-flow tuff.
tuff.
Marcellon
rhyolite ash-flow
Horizontal
dimension,
3.3
mm.
Horizontal dimension, 3.3 rom.
Figure 17
17 (p.
(p. 62)
62)
Photomicrograph of
Marcellon rhyolite
Photomicrograph
of Marce1lon
rhyolite spherulitic
spherulitic texture0
Marcellon
texture.
Horizontal
dimension,
6.4
mm.
Horizontal dimension, 6.4 rom.
62)
Figure 18
18 (p.
(p. 62)
bands.
Photoinicrograph of
of aa spheroid
spheroid with
with concentric
concentric bands.
Photomicrograph
Horizontal dimension,
Horizontal
dimension, 6.4
6.4 mm.
rom.
Figure 19
19 (p.
63)
(po 63)
(p.
and
Photornicrograph of
of aa spheroid
spheroid with
with aa core
core of
of quartz
Photomicrograph
quartz and
Vertical
dimension,
11.2
mm.
epidote. Vertical dimension, 11.2 rom.
epidote.
Figure 27
27 (p.
76)
(p. 76)
in the
Photomicrograph
crenulated shards
Photomicrograph of
of flattened
flattened and
and crenulated
crenu1ated
shards in the
Marquette rhyolite.
dimension, 6.6
Marquette
rhyolite. Horizontal
Horizontal dimension,
6.6 mm.
rom.
Figure 28
77)
28 (p.
(p. 77)
Photomicrograph of
of flattened
Marquette
in the
Photomicrograph
flattened shards
shards in
the Marquette
Horizontal
dimension,
rhyolite ash-flow
rhyolite
ash-flow tuff.
tuff. Horizontal dimension, 6.6
6.6nun0
rom.
(p. 84)
Figure 31
31 (p.
84)
Photomicrograph
Quartzite.
Photomicrograph of
of the
the Waterloo
Waterloo Quartzite.
Horizontal
dimension,
6.6
Horizontal dimension, 6.6nun.
rom.
Figure 33
33 (p.
(p. 87)
87)
View
em thick.
View of
of thin
thin phyllite
phyllite layer,
layer, about
about 40
40 cm
cm
thick.
in middle
middle of
in
of layer.
layer.
Pen lies
Pen lies