Pergamon
Quaternary International, Vol. 28, pp. 147-169, 1995
Copyright © 1995 INQUAJElsevier Science Ltd
Printed in Great Britain. All rights reserved
1040-6182/95 $29.00
1040--6182(95)00037-2
YOUNGER DRYAS ICE-MARGINAL
DEPOSITS IN NORWAY
BjCrn G. A n d e r s e n , * Jan Mangerud,'t Rolf SOrensen,:~ A r n e Reite,§ Harald Sveian,§
M o r t e n Thoresen§ and BjOrn Bergstr6m§
*Department of Geology, University of Oslo, P.O. Box 1047 Blindern, N-0316 Oslo, Norway
tDepartment of Geology, University of Bergen, AllOgt. 41, N-5007 Bergen, Norway
~Department of Soil and Water Sciences, Agricultural University of Norway, P.O. Box 5028, N-1432 As, Norway
§Norwegian Geological Survey, P.O. Box 3006 Lade, N-7002 Trondheim, Norway
INTRODUCTION
in coastal areas beyond the main Y.D. morainal belt.
The corresponding glaciation limits and equilibrium
Distinctive Younger Dryas (Y.D.) marginal moraines lines lay between 350 and 600 m below those of present
fie within a narrow morainal belt, which has been traced day in various parts along the coast.
and mapped from the Russian border in the north
Both the lowering of the equilibrium lines and the
through the fjord districts of northern, western and changes in marine fauna and in pollen flora show
southern Norway to the Swedish border in the south, a that the Y.D. climate was drastically different from
distance of approximately 2500 km (Fig. 1 in Andersen the climates before and after this phase. Even the
et al., this volume). One ridge or two semi-parallel main distinctive Y.D. shoreline, which is called the Main
ridges together with scattered ice-front deltas are most shoreline in north Norway, is probably an indication of
common, but in some areas there are many smaller cold climate, since the line consists of well-developed
ridges within the belt. In most areas the main Y.D. terraces eroded in bedrock in many areas.
moraines represent the largest and most distinctive
The following regional descriptions start with regions
ice-marginal deposits.
in northern Norway and continue through western and
The Y.D. ice fronts pushed into marine environment southern Norway. Some key names are shown in Fig. 1,
in the fjord districts, and marine sediments were and other names are presented on local maps.
deposited at, and beyond, the ice fronts. This kind
of sediments frequently contain marine molluscs that
have been radiocarbon dated, and used to date the
Y.D. sediments, as indicated by Andersen et al. (in
NORTH NORWAY (BY B.G. ANDERSEN)
this volume). In the order of 200 radiocarbon dates
NORDLAND, TROMS AND FINNMARK (FIG. 1)
of molluscs related to Y.D. have been obtained. They
were corrected for a marine reservoir age as indicated
by Andersen et al. (in this volume), who also described General Description
Conspicuous marginal moraines of Younger Dryas
the procedure by which the dates are presented in the
(Y.D.) age have been mapped in the fjord and
following.
The Y.D. glaciers reached a maximum extent in early coastal districts of North Norway, from TrCndelag
Y.D. time in most areas, except in districts near Bergen through Nordland (Andersen, 1975; Rasmussen, 1981;
in western Norway (Fig. 1) where a late Y.D. advance and Andersen et al., 1982), Troms (Andersen, 1968)
was most extensive. Marginal moraines and ice-front 1973). The main moraines lie within a morainal
deltas deposited during late Y.D. advances have been belt, which can be traced almost continuously from
recorded in several areas. They frequently lie from 10 Tr~ndelag to the Russian border, a distance of
to 40 km behind the main early Y.D. ice-marginal approximately 1200 km, and the moraines continue
across the border into Russia. (See Rainio et al.,
deposits.
Glacially tectonized, or glacially overridden AllerCd in this volume.) The Y.D. moraines are usually the
deposits have been found in several areas on the largest and best developed marginal moraines in every
proximal side of the Y.D. moraines. They show that fjord district. In Troms and Finnmark, they represent
the Y.D. glaciers advanced from a few to more than the Troms¢-Lyngen event, and in Nordland, the Tj6tta
40 km in various areas. The ice fronts retreated rapidly event. Several parallel ridges frequently lie within the
morainal belt, most commonly two, but in some areas
both before and after the main Y.D. phase.
A considerable lowering of the equilibrium line took more, and in other areas only one. Where the Y.D.
place in Y.D. time, and numerous Y.D. local moraines moraines cross the fjords there are usually large,
were deposited by cirque glaciers or small local ice caps marked submarine ridges (Fig. 2), and morainal points
147
148
B.G. Andersen
et al.
SW
NE
rROMSA¢
- ,:-- "), /
f~CTromso
)
"'
1M
2OO
-
TRSNDELAG,,O
"Q
',
_~ _ _ r o n ; l l ~ f j o r d 640
J
~Trondheim
,+++÷+4÷++++++++
*÷44÷÷÷++44+÷+4÷+
÷4÷4÷÷÷÷÷+4÷4÷444
+4÷~÷÷4÷4÷44÷~÷÷÷4
444÷4+++4÷÷÷4+++÷4÷
4+÷÷+++÷÷+÷4÷÷++4÷4+÷÷+44~+4÷÷44+++44.÷4.÷÷+÷
÷÷÷÷÷÷÷÷0÷÷÷÷444÷÷o÷~÷4+÷o÷÷0÷4÷44~4÷444444÷÷o*÷4
4
*÷÷÷*.4÷4÷÷÷÷÷÷+÷4+÷÷÷4÷÷~÷÷4÷÷~0÷444~÷4~**o.4÷~4÷+1
÷44++4444++++4÷+4~÷÷+++++÷+÷4÷~4444+~+÷4÷+÷4+4÷÷4++~
+4÷++÷++÷+÷÷4÷÷44+÷÷4444÷÷44÷÷÷4+÷÷4÷÷*÷.4+4÷4~*÷÷+
[ ] c**
WE~.r~o~/~.Nordfjord
..... ~.ognefjord
NO~Wer2~Y~ " H ardan, er
TCrgo
d
-
'",
',;
,,
,,
600
SO;
1:2:]~"
[ ] s.~
PTl ~..,
[ ] r.,
(i] ~
.
FIG. 2. Cross-section of the submarine Younger Dryas (Y.D.)
end-moraine ridge which crosses the mouth of Ranafjord (see
Fig. 7). The lines represent reflectors recorded on a sparker
profile. From Andersen et al. (1982).
RYFYLKE~t~Lvse- . ~ " ~ ,
S~RLANDET
FIG. 1. Names of some districts described in the text.
on both sides (Fig. 3). Laternal moraine ridges lie along
the fjord sides (Fig. 4), except where it is too steep, and
they are used to reconstruct the longitudinal profiles of
the glaciers (Fig. 5). Most profiles show that the frontal
parts of the fjord glaciers were steep, and that, together
with the sharp, steep-sided moraine ridges, which are
most likely push moraines, indicate that the glaciers
were very active. Where the ascending lateral moraines
reach the level of the adjacent mountain plateau, the
morainal belt continues across the plateau to the next
fjord. On the extensive plateaus of eastern Finnmark,
there are commonly many ridges within a wide belt.
The distinctive Main shoreline corresponds with the
Y.D. morainal belt (Figs 3 and 6), and this, in
combination with radiocarbon dates of the moraines,
has been used to verify the Y.D. age of the observed
morainal belts in the different fjord districts.
Within the fjords of Nordland, there are Y.D.
moraines representing the so-called Nordli event approximately 30 km east of the well-defined main Y.D.
FIG. 3. The Troms0-Lyngen (Y.D.) end moraine crosses the mouth of S÷rfjord, a branch of Ullsfjord (Fig. 4) looking north. Note the
steep lateral moraine (L) in the right foreground, and the distinctive Main shoreline in the background, marked with an arrow. Photo
by Royal Norwegian Airforce.
149
Ice-marginal Deposits in Norway
'.
''%
j.
..
./
f'"
•'..? ;
,n....!
J~
T
j
'lj,.ane~ V . ~
IISm
jq J
@
A
'~ ¢
~qB ,i
I
f t
--
e
4~ e'" ~e,e
p~°
.~..F.. "11
i" ....
%',°. °~
o.'°"~
e l Qw
10 km
!
J
I
69
FIG. 4. Marginal moraines within the Troms~ area of Troms. Heavy black lines: Younger Dryas (Y.D.) moraines, xxxx-lines: older
and younger moraines. Short curved lines: Y.D. local moraines.
m
800
700
600
500
SerrjoTd
,- Ullsli
Baisfj
.o°- ...
400
300
200
100
2'0
3() km
FIG. 5. Longitudinal profiles of Younger Dryas glaciers in Balsfjord and Scrfjord (UIIsfjord). Modified from Andersen (1968).
150
B.G. Andersen et ul.
FIG. 6. The Younger Dryas (Y.D.) shoreline in an area near the Y.D. marginal moraine in southern Nordland is frequently represented
by terraces eroded in bedrock. Photo by A. Rasmussen.
moraines (Fig. 7). They have been dated at approximately 10.1 ka BP (Fig. 8)
Radiocarbon Dates of the Moraines
In the order of 40 radiocarbon dates have been
presented of deposits related to the end moraines
in North Norway, most of them by Andersen (1968,
1975), Rasmussen (1981), Andersen et al. (1982),
Marthinussen (1962) and Corner (unpublished data).
All dates, except three, are of marine shells. The
shells were usually collected from sediments within,
or adjacent to the end moraines, or corresponding icefront outwash deltas. All dates presented by Andersen
(1968, 1975) represent some of the first dates of
marginal moraines in Norway, and some of them
have relatively high values for the standard deviation,
which suggests that they are not very accurate. For this
reason, and because of problems with exact correlation
of some of the dated deposits with early or late
phases of the end-moraine formation, the presented
time limits for the glacial phases (Fig. 9) must be
considered tentative. However, the many good dates
of the Tj6tta Substage moraines in Nordland, and of
the TromsO-Lyngen Substage moraines in Troms and
Finnmark, clearly show that they are of Y.D. age.
Stratigraphic observations together with the fact that
there are frequently two parallel main moraine ridges
within the Y.D. morainal belt suggest that this belt may
represent two separate glacial phases: in Nordland an
early phase 10.9(11.2)-10.8 ka BP, and a late phase
10.6-10.5 (10.4) ka BP; in Troms an early phase
11.3(?)-11 ka BP, and a late phase 10.5-10.3 ka BP
(see Figs 8 and 9).
The Advance before and the Retreat after the Main
Younger Dryas Phase
Since most of the dates are of sediments connected
with the moraines, and very few are of deposits in areas
between the moraines, the exact patterns for the retreat
and advance phases are not known. We know that the
retreat following an approximate 12.2 ka old Skarpnes
event (Fig. 7) was rapid, at least 12 km in approximately
300 years, and by approximately 11.9 ka the ice front
was located proximally to the location of the Y.D. end
moraine in Balsfjord. We also know that the Aller0d
period was relatively warm, with a Boreo-Arctic marine
fauna. Therefore, there is good reason to believe that
the ice front had retreated a considerable distance
behind the Y.D. end moraine before it started the Y.D.
advance. An approximate 11.5 ka date of shells from a
glacially overridden deposit about 800 m proximally to
the Y.D. moraine in Ullsfjord supports this conclusion
(Corner, pers. comm.). Dates from Nordland, too,
suggest that the ice front had retreated to a position
near, or proximally to the position of the Y.D. main
moraines at the beginning of the Aller0d period (Figs 8
and 9).
The dates of younger end moraines, which lie a
considerable distance behind the Y.D. moraines, show
that the retreat following the Y.D. main phase was
rapid (see Figs 7 and 8).
The Younger Dryas Shoreline
The most distinctive shoreline in north Norway is
the Main shoreline, which is frequently carved into
bedrock and forms bedrock terraces (Figs 3-6 and 10).
This shoreline is of Y.D. age, and it is usually best
151
Ice-marginal Deposits in Norway
~o*o
,66*30'
**
°.°°
°°
-66"15'
°,"
°°*
•::~.....
46*
i
****°
*.
k
10 km
¢ .
I
|
FIG. 7. Marginal moraines (heavy lines) recorded in southern part of Nordland. The Tj6tta moraines represent the main Younger Dryas
moraines. Modified from Andersen et al. (1982).
NORDLAND
~4C atte
0m~)
"C dmte of delmslt:
• older tkan Use mor-;ne
X corrapondin| with tire morMme
o younger than the morelue
IF
o~
r.~mt~tolc~9~ h
__ m.?
oJ~-"~.I Naniknl 9.6±O . 2 .
10
_ _ _*f~'~'~ywo~'DL7 "~'ricn,.2-1o.,
..-
m.----~-*m-
--
--
"--~ i'0.4 Im
"110..5 u
~,~[~
•
~ TJI~TTA SUIISTAGE
. vq,, 12.2Jut (?!
i
i
II
J
FIG. 8. Time-distance diagram for ice-front fluctuations in Nordland.
,.
152
13. G. Andersen et al.
14C age
TROMS and waternmmt FINNMARK
(h it)
9"
t4C date of depmlt:
¢~7~~ ~.lk.
• older than the moraine
q~..--"~M~en~.'
x corre~ponding wlta the moroine
o younger than the moraine
~,
_~ . B ~ r e , ~ ,
1(
~
11
9.Sko
9.9 ka
.3 kn
12
20
IJ0
6
70
20
30
~0
~e
'
t~
'
h kal
FIG. 9. Time-distance diagram for ice-front fluctuations in Troms and westernmost Finnmark.
developed immediately in front of the Y.D. moraines.
In addition, the outwash deltas which correspond with
Y.D. moraines were graded to the Main shore level.
The late glacial shorelines within the fjord districts
proximally from the Y.D. moraines are generally
indistinct, and lie at lower shore levels.
The Younger Dryas Marine Fauna
A high-Arctic Portandia arctica fauna dominated by
P. a., Macoma calcarea and Hiatella arctica frequently
occurs in clays deposited near the Y.D. ice front.
The same fauna was also found in some older
clays, but a Bathyarca glacialis fauna dominates in
Y.D. glaciomarine clays deposited after the main
Y.D. moraines, such as in clays deposited at the
approximately 10.1 ka old Nordli moraines. A BoreoArctic fauna with thick-shelled specimens of Mya
truncata, Chlamys islandica, Astarte elliptica, and so
on dominates in most Aller~d sediments which were
deposited at some distance from the muddy water near
the ice fronts, and the same kind of fauna is found
frequently in Preboreal sediments.
The Younger Dryas Local Glaciers and Glaciation Limits
Numerous small, distinctive moraines deposited by
local glaciers lie in the mountains beyond the Y.D.
morainal belt, and no corresponding moraines exist
in areas on the proximal side of this belt (Figs 4
and 10). Therefore the moraines are of Y.D. age or
older. Since many of the local moraines lie in areas
immediately outside the Y.D. belt, which are areas
that were covered by the approximately 12.2 ka old
Skarpnes fjord glaciers, they must be younger than
12.2 ka BP. Some of the local glaciers deposited
end moraines in the shore zone, and particularly one
of the moraines has a well-defined outwash delta at
Main shore level (Fig. 10). At another locality, an
approximately 10.5 ka old marine bed in front of
a local moraine, was correlated with the moraine.
Therefore, all considered, most of the local moraines
must be of Y.D. age. Based on the location of
the numerous Y.D. local moraines and the altitudes
of the glaciated mountains, Andersen (1968, 1975)
calculated a Y.D. glaciation limit and equilibrium
line at approximately 475 + 50 and 550 + 50 m
below present day glaciation limit/equilibrium line in
Troms and Nordland, respectively.
T R O N D E L A G (BY A. REITE, H. SVEIAN,
M. T H O R S S E N AND B.G. ANDERSEN)
The districts adjacent to the extensive Trondheimsfjord
have been studied by many Quaternary scientists,
and the following presentation is based on numerous
publications and reports, such as Reite (1994), Reite
et al. (1982), Sveian (in preparation), and Sollid et al.
(1976, 1979), in addition to unpublished information
from several scientists at the Norwegian Geological
Survey (NGU).
General Descriptions
The Trondheimsfjord is a wide fjord consisting of
several overdeepened rock basins partly filled with
thick units of glaciomarine sediments. It is surrounded
by low-lying districts which are frequently covered
with glaciomarine deposits. The sea level was in the
order of 150-200 m higher than today when the ice
front was located within the fjord area. Wide valleys
lead from the fjord eastward through a low mountain
range at the Swedish-Norwegian border. Ice from the
Ice-marginal Deposits in Norway
153
O
~z
.=. =
~=.=
~,z-
~.<
~5
r,
154
B . G . Andersen et a/.
~ o.
°o
VUKU
I
I.ON-. ~.llOq
The belt, which represents the Tautra Substage, is by
far the most dominant, and can be traced as an almost
continuous belt over considerable distances, except
within the southern mountain districts. The Tautra
moraines are of early Y.D. age, and there is another
almost continuous morainal belt representing a late
Y.D. event, the Hoklingen Substage, approximately
10-30 km behind the Tautra moraines. Parts of the
end moraines were deposited in marine environment,
and they are frequently composed of both till beds,
glaciomarine and glaciofluvial beds. Narrow endmoraine ridges, often 8-10 m high, are commonly
found on higher terrain.
The Age of the Younger Dryas Moraines
"...-
N
f"..o..
|
........-,.... (
..¢
?
T
30 km
FIG. 11. Marginal moraines in the Trondheimsfjord area of Central
Norway. The Tautra moraines represent the main Younger Dryas
(Y.D,) phase and the Hoklingen moraines represent a late Y.D.
phase, Modified from Reite (1994).
central parts of the Scandinavian ice sheet could easily
cross this mountain range, and it pushed into the
Trondheimsfjord area with a long fairly straight-lined
ice front. It crossed this fjord during the first half of
the Younger Dryas (Y.D.) period, with an extensive
calving front at Tautra, and it deposited a marked end
moraine on the Fosen Peninsula (Fig. 11). Only on the
south side of the Trondheimsfjord do deeper valleys
lead into higher mountains and mountain plateaus from
which valley glaciers entered the fjord district.
The coastal areas to the west of the fjord were
deglaciated between 13,000 and 12,000 years ago,
and four more or less parallel main morainal belts
have been mapped in areas from the coastline to the
districts near the Swedish border (Fig. 11). However,
detailed mapping carried out by Sveian (in preparation)
in the northern part of Tr0ndelag indicate that there
are many ice-marginal deposits located between the
main moraines. Their location is generally controlled
by topographic features rather than climatic events,
and the ice recession was usually rapid between the
main morainal belts.
Fossiliferous glaciomarine beds lie both below, within
and on top of some of the observed end moraines.
In addition thick fossiliferous glaciomarine beds, in
general clay beds, lie on the distal side of the
moraines. Most of the dates related to the moraines
are radiocarbon dates of marine shells from this kind
of deposits. However, some few dates are of organic
lacustrine deposits and of whale bones. The Tautra
moraines are, in fact, most accurately dated by means
of whalebones, and gyttja from below and on top of a
laminated lacustrine unit deposited in a lake which was
dammed by the Tautra Substage glaciers.
Figure 12 is a time-distance diagram for ice-front
fluctuations based on dates from the southern parts
of Tr0ndelag. The diagram is modified from Reite
et al. (1982) and Reite (1994). Based on the dates,
they suggested an age between 10.8 and 10.5 ka BP for
the Tautra morainal belt. This time bracket again relies
very much on the mentioned two dates of gyttja above
and below the laminated Y.D. unit. However, if only
dates of fossils from the marine deposits are considered,
the oldest age limit for the Tautra moraines could as
well be approximately 11 ka BP. Keep in mind that
all dates of marine fossils are corrected for a reservoir
age of 410 or 440 years, and with a somewhat higher
reservoir age for the fossils (see Andersen et al. in this
volume) the correct radiocarbon age for the lower limit
of the Tautra event could very well be approximately
10.8 ka, even based on dates of marine fossils.
Numerous dates of marine shells from till beds and
end moraines in the northern part of Tr0ndelag were
presented by Bergstrfm, Olsen and Sveian (Bargel
et al., 1994). However, no time--distance diagram
was presented, and the exact correlation with the
moraines is problematic in some cases. Therefore,
only the plotted dates and the location of the moraines
are shown in Fig. 13. The authors concluded that the
dates support an age of 10.8-10.5 ka BP for the
Tautra morainal belt, and they dated an older belt
of coastal moraines at approximately 12.4--12.3 ka BP.
This coastal belt, which we tentatively call the 'Outer
Coastal Moraines', approaches the Tautra moraines in
the northernmost part, and many dates of marine
beds below Tautra age sediments range between 11
and 12.5 ka BP in that area. This indicates that the
Ice-marginal Deposits in Norway
J4c at,
i n u.)
~
155
G
10 ¸
aO
---
--
~AUTRA
~-'?
(10.4-10.3kltl
SUBSTAG,II0.S-10Jktl
O
M, JdOItAINIIS(!1.4-12.3k8)
"
~o
b
I
4o
!
x
I
n
L
,
~i. t~J x,
le
,
~
•
~o
~o
,
6,
.~,--
FIG. 12. Time-distance diagram for ice-front fluctuations in the Trondheimsfjord area. Modified from Reite et ai. (1982) and Reite
(1994). (a) Dates of lacustrine gyttja, (b) dates of whale bone. Legend: see Fig. 9.
ice front there was located at or behind the position
of the Tautra moraines as early as in Btlling time.
The Hoklingen morainal belt is located from 10
to 30 km behind the Tautra belt. The available
radiocarbon dates of marine fossils suggest that the
Hoklingen moraines are of late Y.D. age, about
10.3-10.4 ka old, and marine sediments proximally to
the moraines are dated at 10.2-10.3 k a a n d 10 ka BP
(Sveian, 1989).
The Vuku morainal belt lies approximately 20 km
east of the Hoklingen moraines. The moraines are
.65 e
relatively small, and they are dated at about 10-9.8 ka BP.
A few more prominent moraines, representing a GrongSn~sa event, lie 30--40 km behind the Vuku moraines at
Sn&sa, and the suggested age is 9.8-9.5 ka BP.
The Younger Dryas Advance
Marine AllerCd deposits below basal till that was
correlated with the Tautra end moraines have been
observed a considerable distance behind the Tautra
morainal belt, approximately 15 km at one locality
and possibly 35 km at another. As mentioned before,
the ice front had retreated to the position of the Tautra
moraines as early as in mid-Btlling time within the
northern parts of TrCndelag. Therefore the retreat
behind the position of the Tautra moraines was most
likely a combined Btlling-Allertad retreat, and the
advance to the Tautra moraines was a late Aller~d(?)
early Y.D. advance.
WESTERN NORWAY (BY J, MANGERUD)
.--o_
I
I
I
I
A synthesis of the palaeoenvironmental and palaeoclimatic changes in western Norway during the AllerCdYounger Dryas (Y.D.)-Early Holocene is presented
recently by Birks et al. (1994). A short review of glacier
fluctuations is also given by Nesje and Dahl (1993). The
present paper is focused on the identification and age
of the Y.D. end moraines.
The Area between Hardangerfjord and Sognefjord
I
I
Identification of the Younger Dryas Moraines
In this area, the Y.D. moraines were not properly
identified and mapped until the 1970s (Mangerud,
1970; Aarseth and Mangerud, 1974). The reason is
simply that most of the end moraines on land are very
small, 1-5 m high, and discontinuous.
Two new techniques were crucial for solving the
problem:
FIG. 13. Radiocarbon dates of molluscs, mostly from tills and
ice-marginal moraines or glaciofluvial deltas, and a few from
glaciomarine clays in northern Tr~ndelag. (Compiled by Bergstr6m,
Olsen and Sveian, in Bargel et al., 1994.)
(1) Mapping the sub-marine moraines with penetrating
echo-sounder, which enabled Aarseth and Mangernd
(1974) to connect the terrestrial moraines with moraines
....
156
B . G . A n d e r s e n et al.
6"
8"
84"-
:" [
( i
, i
o
11070~180,~
10940±180[~
"Z.
Z
10230~180 i
0
12220±150
i
~>
N
,~Se°
0
5
k
J
10km
==
-.,,..J
10260i120
/
10940±180 /
End moraines
!
0@@@@@@Ice-front deposits without constructional
morphology
11265±100 /
HERDLA
MORAINES
Assumed position of ice-front
Radiocarbon dates from till and sub-tilt
sediments. Locality marked by cross
10260¢120 Dates from sediments not disturbed by ice
FIG. 14. Map of the coastal area between Hardangerfjorden and Sognefjorden. The Younger Dryas (Y.D.) Herdla moraines are indicated.
Radiocarbon dates in boxes are from shells in till or in sub-till sediments, which give a m i n i m u m measure of how far east the ice front
withdrew during the AUerod, and also prove a glacial re-advance subsequent to the given ages. Dates that are not in boxes (Blomcy,
Agotnes, Vinnes) show sites with an undisturbed AllerCd-Y.D. sequence, which demonstrate that the Y.D. re-advance did not overrun
these sites. O n the inset map is shown the Y.D. moraines around southern Norway; from Aarseth and Mangerud (1974), with some
additional dates. In order to give identical n u m b e r s to Fig. 2, all dates on marine fossils are corrected for a marine reservoir age of
440 years (whereas in the original they were corrected for 410 years).
157
Ice-marginal Deposits in Norway
0
0
=!
i;
0
~3NNIA
. . . .
-:
~.,~,=.~_~.,~.
k'~~t'~'~Tv~--
--'(~'-'-j~'~N'~'TT
.
.
.
0
=.~
.
+, +, +p ÷, ÷= +~ +,
0 0
O0
09t~0t'£ 6
C~9-1
~_=.~
I,~9 "1
~;~9 -1
~z9-108t;OZO ~t
081~0t'6 0I 061~0Z0 It
4
E- o
9®
=m
E~
o~
I
I
i
I
I
I
I
I
g
0
I
I
I
I
~
I
I
I
,
I
0
0
0
,
,
,
i
I
,
1
,
1
0
0
0
,
,
,
I
I
I
l
I
158
B . O . Andersen et al.
across the numerous fjords and sounds. In fact, the
moraines are often larger on the fjord bottoms, which
were the valley floors, compared to the land areas. In
this way a nearly continuous end moraine zone, named
the Herdla Moraine, was mapped.
(2) Radiocarbon dating. In the Bergen area tills with
shells or shell fragments had been known from the
turn of the century. However, the ages of the shells
were unknown until the first radiocarbon dates yielded
AllerOd and Y.D. ages (UndAs, 1963; Holtedahl, 1964),
demonstrating that the Y.D. glacier re-advanced across
that area. Sub.sequenfly similar dates were obtained
from many different sites (Fig. 15) (Mangerud, 1970;
Aarseth and Mangerud, 1974; Mangerud et al., 1979;
Mangerud, unpublished data). The crucial observation
is that all sites yielding ages in the range 10-12 ka BP
of shelly tills or sub-till sediments are situated east of
(proximal to) the Herdla moraine. Shortly west of the
Herdia moraine undisturbed stratigraphic sequences
were discovered (particularly Blomcy, Agotnes, Vinnes,
Figs 14 and 15), covering the entire period from
12,000-9000 (Mangerud, 1970, 1977; Ovstedal and
Aarseth, 1975), proving that the Y.D. re-advance
did not extend beyond the Herdla moraine. In this
area only one end moraine zone of Y.D. age is found,
and it was formed very late in Y.D. (Fig. 15).
The correlation of the Herdla moraine across
Hardangerfjord was established by Follestad (1972)
and Holtedahl (1975). Along the southern side of
Hardangertjord Follestad (1972) mapped lateral moraines
which demonstrated that the Y.D. glacier indeed was
very thick (Fig. 16).
Age and amplitude of the Younger Dryas re-advance
All radiocarbon dates from Y.D. till or sub-till
sediments are of marine shells. They are corrected
for a reservoir age of 440 years, whereas the Y.D.
reservoir age probably is 700-800 years (Andersen
et al., this volume). The dates demonstrate that the
ice withdrew far inland during the AllerCd (Figs 14
and 15). The time for the start of the Y.D. re-advance
is not precisely known, except that it post-dates the
age 11,23-11,53 ka BP of the site (Trengereid) which
lies farthest inland (Fig. 14). The re-advance ended
shortly before 10 ka BP when the ice front reached
the Herdia moraine. How fast the ice front advanced
between these two end points cannot be determined
in detail. The simplest assumption is that the glacier
advanced more or less continuously during the entire
Y.D., especially when considering the ampfitude of
the re-advance in the deep fjords (see below). This
conclusion is also supported by the interpretation of
nULLI. W
E
m.u.I.
NE
m.uJ.
-1500
:1
m.a.Ll,
lr~O- SW
Q
1000
-1000
-5OO
GO0~tve
11.2~180
-5OO-
-5OO
FIG. 16. Longitudinal profiles along fjords where the glacier re-advanced during the Younger Dryas (Y.D.) The upper profile is
Herdlefjorden-Scrfjorden (the short fjord connecting the two fjords is omitted), see Fig. 2. The easternmost site (Trengereid) with
Aller#d dates is marked. The glacier profile is from Hamborg and Mangerud (1981). Note that the fjord along most of the distance
of the Y.D. re:advance is 300-500 m deep. The lower profile is Hardangerfjorden, simplified from Follestad (1972). The glacier surface
is mapped by means of lateral moraines. The innermost proven AllerOd site (~lve) in this fjord is also marked, but the ice probably
withdrew considerably farther inland. The fjord is around 10 km wide along this profile, and as shown, more than 500 m deep along
long stretches.
Ice-marginal Deposits in Norway
the marine sequence at Vinnes, just outside the Herdla
moraine (Aarseth 1994 pers. commun.). However,
the envelope of dates also allows for a fast first readvance to the vicinity of the Herdla moraine around
10.8 ka BP, followed by a minor withdrawal, and a
second re-advance near the end of Y.D. (Fig. 15), as
proposed by Anundsen (1985).
The minimum extent t~f the re-advance is some
40-50 km, measured from Trengereid to the Herdla
moraine. However, a diverse AllerOd mollusc fauna
with nine species, including Clamys islandica and even
Modiolus modiolus found at Trengereid, indicates that
the ice front was much farther inland when that fauna
lived there.
Even more important in judging the amplitude of the
Y.D. re-advance is the location of the lateral moraines,
which demonstrates that the glacier front was steep and
the glacier was thick (Follestad, 1972, Aarseth and
Mangerud, 1974). In addition, the re-advance occurred
in several hundred meter deep fjords (Fig. 16). Thus
along most of the profiles shown in Fig. 16, the ice was
more than 800-1000 m thick in areas that were ice free
before the re-advance. Mangerud (1980) interpreted
the large re-advance in this area, compared to, for
example, more easterly areas of Scandinavia, as partly
a result of accumulation of snow on extensive mountain
plateaux dose to the coast, which could feed ice flow
down narrow valleys and fjords.
The Area North of Sognefjord
South of Sognefjorden the main ice sheet nearly
reached the outer coast during the Y.D. glacial
maximum, and no local glaciers existed beyond the
ice sheet. This pattern changes completely north of
Sognefjorden where the marginal moraines deposited
by the main ice sheet continue inland; in Nordfjord they
occur in the middle part of the fjord, and in Storfjord
and Romsdalsfjord close to the head of the main fjords.
North of Sognefjord numerous cirque glaciers, and even
an ice-cap (/ldfotbreen), existed in the mountains west
of the main ice sheet during the Y.D.
Moraines deposited by the Scandinavian ice sheet
Fareth (1987) mapped the Y.D. moraines, the Nor
moraines, in Nordfjord, where large frontal deposits
occur across the main fjords and valleys, and long
segments of laternal moraines lie along the valley
slopes. This allowed him to reconstruct in detail an
extensive system of long and thick outlet glaciers
from the ice sheet. Fareth dated the Nor moraines
to approximately 10,440 + 170 BP (T-645), using
molluscs in glaeiomarine clay in the distal part of
an ice-front delta (Fig. 17). Mangerud et al. (1979)
obtained a slightly older age (10,750 + 170, T-2304)
on shells in till distal to the Nor moraines, and
stratigraphically below the mentioned glaciomarine
clay. This demonstrated that in this area there had
indeed been a re-advance that culminated early during
the Y.D., and that the glacier during this early readvance had reached beyond the main (Nor) moraines
159
(Fig. 17). Klakegg and Nordahl-Olsen (1985) obtained
more dates (plotted on Fig. 17) confirming these
conclusions. As important was their discovery of shells
in till some 30 km proximal of the Y.D. moraines
from which were dated at 11,360 + 70 BP (T-6091)
(Fig. 17). Thus the Y.D. re-advance (e.g. across the
514 m deep lake Hornindalsvatnet) had been of the
same order of magnitude as in the Bergen area, but in
the Nordfjord area it culminated early during the Y.D.
Rye et al. (1987) obtained dates that showed that the
glacial retreat after the Y.D. was fast.
North of Nordfjord Sollid and SCrbel (1977, 1979)
mapped the marginal moraines deposited by the
Y.D. ice sheet close to the head of Storfjorden and
Romsdalsfjorden. They also reported lateral moraines
as high as 1450 m a.s.l. In that area no radiocarbon
dates related to the moraines are reported.
Local glaciers
Cirque glacier moraines were first described in the
coastal mountains of this area by Kaldhol (1930).
Reite (1968) obtained a radiocarbon date, which
demonstrated that the ice sheet withdrew from the
area near the cirque moraines during the AllerCd, and
he argued that the large depression of the equilibrium
line shown by the cirque moraines indicated that they
were of Y.D. age. This age was finally confirmed for
a cirque moraine at Kr~kenes (Fig. 14) by means of
coring and dating sediments in a lake downstream of
the moraine (Mangerud et al., 1979; Larsen et al.,
1984). In the lake they found organic sediments which
demonstrated that this particular cirque glacier did not
exist during the AllerCd (between 12,320 + 120, T-2534
and 11,100 + 80, T-2532), but overlying laminated clay
showed that it was formed at the onset of the Y.D. and
disappeared near the transition to the Holocene. The
Vedde Ash was found in the middle of the laminated
unit (Mangerud et al., 1984). This ash was originally
dated to 10.6 ka BP, but AMS dates of terrestrial
macro plant remains gave an age around 10.3-10.4 ka
BP (Bard et al., 1994; Mangerud et al., unpublished
data from Kr~kenes). This type of investigations
has been continued by S~nstegaard and co-workers
who have cored many lakes downstream from local
glaciers. They have not found any other site where
they could prove that the cirque glacier disappeared
completely during the Aller~d, and their preliminary
conclusion was that most local glaciers survived during
the AllerCd, although they were smaller than during the
Y.D. (S¢nstegaard, 1994, pers. commun.) The glacier at
Kr~kenes was situated at lower altitude than most of
the other Y.D. cirque glaciers (Larsen et al., 1984).
Therefore this glacier was more sensitive to climatic
fluctuations, and it disappeared during the climatic
amelioration of Aller~d, which glaciers at higher
altitudes survived.
A large number of Y.D. moraines deposited by
cirque glaciers have been mapped between Sognefjorden
and Romsdalsfjorden (e.g. Fareth, 1987; Sollid and
SCrbel, 1979; Larsen et al., 1984). They are generally
160
B (,. A n d e r s e n et al.
~o
o
~
0
~o
t~UlOJOUJ ~I)
uoloP.L3e
0
l
~.~
0
•
•
•
~UIDJOW
SaU!OJOW
~I~AJSU!A
0
8,,=,
sauioJow~JONb~V~l~
sau!oJOW
5no4ap~oA
o"
i~
e,
Z~
I\\
sauioJOUJ )I!AO(~ ~-~
o¢
au,oJowpolsaa-I
:0
~5
o
8
o
8
o
8
0
o
o
0
r~
6
Ice-marginal Deposits in Norway
well defined, 2-10 m high ridges, curving across the
mouth of cirques or across valleys. Also some larger
individual glaciers existed during the Y.D. The largest
was an ice cap on the plateau where present day
Alfotbreen (glacier) is located (Fareth, 1987; Klagegg
et al., 1989). This glacier reached its Y.D. maximum
before the 10.3-10.4 ka old Vedde Ash was deposited
(S4anstegaard, 1994, pers. commun. ).
Equilibrium line depressions
The problems related to the calculation of palaeoequilibrium line altitudes and comparing them with the
present day situation were recently discussed by Dahl
and Nesje (1992). Here we will mainly list some results.
The largest depression of the Y.D. equilibrium line
altitude (ELA) was along the outermost coast, where
Larsen et ai. (1984), for 14 cirque glaciers, calculated
a mean lowering of 600 m compared with the present
day (extrapolated) steady-state ELA given by Ostrem
and Liest~l (1964). (Note that Larsen et al. added
100 m and cited 700 m depression compared with
the climatic ELA for 1931-1960.) Fareth (1987) found
a depression of ELA of approximately 450 m for
Y.D. valley glaciers in the middle and inner parts
of the Nordfjord, and slightly less for some local
glaciers, when comparing with Ostrem and Liestals
map. Dahl and Nesje (1992), and Nesje and Dahl
(1992) found similar values, using the same method
as Fareth. However, Dahl and Nesje (1992) found that
the ELA depression for one particular Y.D. cirque
glacier was only about 170 m if they compared with
ELA on adjacent present day cirque glaciers with
similar location where winter accumulation is strongly
increased by wind-blown snow.
161
SORLANDET AND RYFYLKE (BY B.G.
ANDERSEN AND B. BERGSTROM)
Description of the Moraines
The description in this chapter is based mainly
on information presented by Andersen (1954, 1960),
Anundsen (1972), and Bergstr6m (in preparation).
The Younger Dryas (Y.D.) morainal belt continues
from the Hardangerfjord area through the Ryfylke
fjord district and eastwards across the plateaus and
valleys of the inland part of S¢~rlandet to reach the low
east coast of S•rlandet near Grimstad, and to continue
along the coast to the Oslofjord district.
Long outlet fjord glaciers with steep fronts occupied
several narrow fjords in Ryfylke, and distinctive
moraine ridges were deposited along the glacier
margins. Best known are the moraines in Lysefjord
where Esmark (1824) observed the famous Esmark
Moraine (Figs 18, 19 and 20). Several moraine ridges,
more or less parallel, lie within the morainal belt which
crosses the mountain plateaus between the valleys on
S¢rlandet. Bare bedrock is usually exposed on the
plateaus on the proximal and distal sides of the belt.
Lakes are dammed by the moraines in most of the
valleys, and long outwash valley trains were deposited
downvalley from the moraines. The outwash plains
were graded to sea levels 30--60 m above the present,
but postglacial river erosion has removed much of the
original outwash sediments.
Two sizeable lakes are dammed by considerable icefront outwash deltas and end-moraine ridges where the
morainal belt approaches the coastline near Grimstad.
From here on, the belt continues northeastwards across
several islands which are partly or totally covered
FIG. 18. The Lysefjord glacier 11 to 10 ka BP. Heavy lines: observed marginal moraines. Es: the Vassryggen (Esmark) end moraine.
From Andersen (1954).
B.G. Andersen et al.
162
IOOO,
m
500,
m
sealevel
Y.D.
t~
r
e "~
n
.
,
,
io
k,
.5001
lU
FIG. 19. Longitudinal profile of the Lysefjord glacier. Thin line: observed lateral moraines. Shaded bumps: end moraines. From
Andersen (1954).
by Y.D. glacial and glaciomarine deposits, such as
Jomfruland Island (Fig. 22).
The Age of the Marginal Moraines, and the Size of
the Glacier Fluctuations
Very few dates exist of deposits related to the
described moraines in S~rlandet and Ryfylke. Some
dates have been obtained from the easternmost and
westernmost parts where the Y.D. glacier pushed into
marine environment. Two radiocarbon dates at about
10.8 and 10.6 ka BP, in deposits from the moraine
on Jomfruland Island confirm the Y.D. age of this
moraine (Bergstrrm, in preparation). A n o t h e r approx.
11.4 ka BP date of marine deposits exposed below a
till bed, about 10 km inland from Jomfruland, shows
that the glacier retreated a considerable distance behind
the position of the Y.D. moraine in AllerOd time,
before the advance to the moraines (Bergstrrm, in
preparation). Some dates from the fjords in Ryfylke
show that the front of the fjord glacier had retreated
to about the position of the Y.D. moraines as early as
in late BOiling time (Fig. 21). A Boreo-Arctic fauna
with Mytilus edulis has been observed in late Boiling
marine clays below Y.D. outwash about 200 m from
the Lysefjord end moraine (Andersen, unpublished
data). This shows that the marine water temperature
was favourable at that time, and the ice front must have
been located in Lysefjord well behind the position of
FIG. 20. The Vassryggen (Esmark) end moraine which dams Lake Haukelivann. The outwash plain in the foreground was graded to
a sea level about 40 m above present sea level.
Ice-marginal Deposits in Norway
14C age
(ka}
163
RYFYLKE
1o.
10-
i
Y.D. moraine
11"
?
12
12
~--
Late Boiling moraine
1Okra
14e date of aenost*: • older than the moraine
x corresponding with
the moraine
~
FIG. 21. Time-distance diagram for ice-front fluctuations in Ryfylke. Dots: dates of marine molluscs from sediments which are older
than the moraine, x: date of molluscs which are of the same age as the moraine. Modified from Blystad et al. (1982).
t h e Y . D . e n d - m o r a i n e b o t h in late BOiling a n d A l l e r 0 d
times. T h e r e f o r e t h e size o f t h e Y . D . a d v a n c e in
R y f y l k e was m o s t likely o f t h e s a m e o r d e r o f m a g n i t u d e
as t h e a d v a n c e in H a r d a n g e r f j o r d (see M a n g e r u d in this
volume).
L a t e A l l e r 0 d d a t e s o f shells f r o m m a r i n e d e p o s i t s
b e l o w till b e d s a s h o r t d i s t a n c e o n t h e distal side o f
s o m e Y . D . m o r a i n e s suggest a late A l l e r 0 d o r e a r l y
Y . D . glacier a d v a n c e b e y o n d t h e distinctive Y . D .
m o r a i n e s ( A n u n d s e n , 1977; B l y s t a d et al., 1984), a n d
it was i n d i c a t e d that this a d v a n c e was a surge, since
no corresponding end moraines were observed. An
a p p r o x . 10.8 ka B P d a t e was o b t a i n e d of a g l a c i o m a r i n e
silt with a h i g h - A r c t i c P o r t l a n d i a arctica f a u n a , which
FIG. 22. Jomfruland Island on the SE coast of Norway is a Younger Dryas end moraine. Bare bedrock is exposed on the many small
islands on the proximal side of Jumfruland.
164
B . G . Andersen
et al.
THE OSLOFJORD REGION, SOUTHEASTERN
NORWAY (BY R. S~RENSEN)
Deglaciation chronology for the Oslofjord region has
been revised several times during the last two decades
(Sorensen, 1979, 1983, 1992a; Klakegg and S~rensen,
1991). A considerable amount of new information
about ice-marginal deposits in the Oslofjord region
has been presented through the modern Quaternary
mapping programme of the Norwegian Geological
Survey. This information has been taken into consideration in this paper. The term chronozone is substituted
with chron, since the unit is based on 14C geochronology.
The different zones of ice-marginal deposits are
abbreviated IMZ. Most of the presented dates are
radiocarbon dates of shells.
Older Dryas and AllerOd (12-11 ka BP)
The Hvaler/TjCme-Trollhiittan Ice-marginal Zone
(Line 1, Fig. 23)
FIG. 23. Revised deglaciation of the Late Glacial and Early
Preboreal in the Oslofjord region (modified from Klakegg &
S0rensen, 1991). Line 1: the Hvaler-Tj6me Ice-marginal Zone
(IMZ). (Trollh~ittan). Line 2: the Onsoy-Slagen IMZ (Levene).
Line 3: the Ra IMZ. (Sk6ve-Billingen). A: the Eidet locality
(Rygg, 1991). Line 4a: the ,~s IMZ. B: the Fokser6d locality
(SOrensen, 1992). Line 4b: the Ski IMZ. Line 5: the Aker IMZ.
B: the Bommestad locality (S0rensen, 1992b). Sh Slagen; On: Onsoy;
Go: Goverud; M: Mona. Projection line I: Eastern side of Oslofjord,
Fig. 25a. Projection line II: Western side of Oslofjord, Fig. 25b.
Mollusk fragments just above diamict sediments at
Tj~me have been radiocarbon dated to 11,975 + 155
BP. This gives a minimum age of the Hvaler/Tj~me-
~¢3
Lithology
"o
•
Environ,- ¢n ment
rR
Foreshore
-~
overlies a till bed a short distance beyond a marked
Y.D. moraine. Blystad et al. (1984), correlated this
silt with the moraine, and the high-Arctic fauna in the
glaciomarine silt suggests that the ocean temperature
had changed drastically from late Bolling/Allerod time
to Y.D. time.
The time-distance diagram (Fig. 21) is a composite
diagram based on radiocarbon dated marine deposits
from three fjord branches in Ryfylke (Blystad et al.,
1984; Anundsen 1987; Andersen, unpublished data).
III Coarsening
"
upwards
4"
- ::~:--'._
20
Glacio-
- .....
" p,...."
....
". .......
=,v,..,A, ....
15
marine
fan
-'.. ........
II
....
Lower-slope
bottomsets
"'7"'~"
/
The Younger Dryas Equilibrium Line
Based on the assumption that distinctive marginal
moraines must have been deposited below the altitude
of the equilibrium line, a minimum altitude for the
Y.D. equilibrium line was calculated at 800-1000 m
above present sea level, which is about 730--930 m
above the Y.D. sea level. The present-day equilibrium
line was calculated to lie about 1300-1400 m above
sea level. Therefore, Andersen (1954) and Anundsen
(1972) estimated a Y.D. equilibrium-line depression of
maximum 400-550 m and 350--400 m for southern and
northern parts of Ryfylke, respectively.
10630+160
- - 10 350 + 120
10570±110
~
• • !
•
N
5
Glaciomarine
1
•
•
•
o
10680±100
10 680 ± 170
fan
Ice-contact
fades
0
0
FIG. 24. Section from the Eidet gravel pit (Locality A, Fig. 23), with
main sediment units, environmental interpretation, and radiocarbon
dates. The upper and the lower levels are accelerator datings, on
Foraminifera tests. The other datings are conventional (modified
from Rygg, 1991).
Ice-marginalDepositsin Norway
Trollhiittan IMZ (Bergstrem et al., 1992), cf. Older
Dryas, Lundqvist (this paper). This is a slightly older
age than suggested by Serensen (1979). An Older
Dryas age of this ice-margin is indirectly supported
by radiocarbon dates (at the Marine Limit) ranging
from 11.9 to 11.4 ka BP, midway between the
Hvaler-Trollh,~ittan and Onsey-Levene ice-marginal
zones south of Halden (Serensen, 1992a, Fig. 23a
and b).
The Onsey/Slagen-Levene Ice-marginal Zone (Line 2,
Fig. 23).
This ice-marginal zone consists of two sub-parallel
ridges occurring on both sides of the Oslofjord. The
age is discussed by SCrensen (1992a), and is set to
Late Aller~d (11.2-11.4 ka BP). The short stop in
the glacier-front recession may reflect the start of
the climatic deterioration culminating during Younger
Dryas (Y.D.). New mapping (Olsen and L~awe, 1984;
Klakegg and Scrensen, 1991) shows that these icemarginal lines end at the Ra ridges just north of
locality B on Fig. 23. Therefore, during the Y.D. main
glacier advance, when the Ra ridges were deposited,
the glacier advanced further than the Levene glacier
in areas southwest of locality B. Radiocarbon dates
of shells from marine sediments, about 2 km behind
the Ra ridges, indicate a substantial Y.D. re-advance
(Fig. 25b), and the size of this advance increases
westwards towards the Krager~ region (BergstrCm,
in press).
165
been deposited near the glacier front and dates the final
retreat from the Ra ridge in this area (Rygg, 1991).
A section at Foksered (Locality B, Fig. 23) has been
described by Serensen (1992a, b). The Ra complex at
this site consists of two distinct ridges, composed of
mainly diamict sediments. The average of three dates
of shells from the diamictons is 10,663 ka BP. Both
at Fokser~d and two other sites on the western side
of the Oslofjord (Bommestad and Salstsene, B and S
Fig. 23), the last early Y.D. re-advance appears to have
been more extensive than the first, el. descriptions by
Brandal and Heder (1991) from the eastern side of the
Oslofjord.
The Late Younger Dryas
The As ice-marginal zone (Line 4a, Fig. 23)
The As IMZ represent a complex of ice-marginal
ridges (Nordahl-Olsen, 1990). They are mainly deposited
below ML. The correlation of this IMZ with the
Swedish deglaciation pattern is still unclear (Lundqvist,
1988), but a connection with the drainage of the Baltic
Ice Lake has been suggested (Lundqvist, this volume).
This may be true for the southernmost part of the
As IMZ (cf. Lundqvist, 1988; Fig. 8), but not for
the main ridge system. The westward continuation
of the As IMZ is still uncertain. It may coalesce
with the Ski IMZ on the western side of the Oslofjord,
cf. Klakegg (1991), and Bergstrem (1988). The large
ice-contact delta at Mona has been correlated with
The Early Younger Dryas
the As IMZ. Marine mollusc shells found in mud
facies
on the upper delta slopes has been dated to
The Ostfold and Vestfold Ra ridges (the Ra IMZ)
10,430
+ 160 and 10,670 + 270 BP (Holtedahl, 1974;
(Line 3, Fig. 23)
Andersen,
1975), and marine shell fragments in mud
The Ra ridge complex consists of two or more
below
diamicton
in the main ridge of the As IMZ has
prominent ice-marginal ridges, both above and below
recently
been
dated
to 10,215 + 95 BP. The available
the marine limit (Olsen and Lcwe, 1984; Kj~ernes,
dates
are
conflicting,
and the last date is considered
Robertsen and Bargel, 1991; SCrensen, 1992a). Of
most
reliable.
Bjerlykke
(1900) recognized evidence
several 'key localities' with well-dated sections, only
of
an
ice-front
oscillation
at the main As IMZ ridge.
the Eidet site (Figs 24 and 25) on the east side of the
Later
investigations
have
confirmed
this, but the size
Oslofjord (Rygg, 1991) will be described in detail as
of
the
fluctuation
is
unknown.
an example. Some supplementary sites on both sides of
the Oslofiord are also mentioned (Fig. 23). A number
of unpublished radiocarbon dates are presented in the
recession diagrams (Fig. 25a and b).
The Ski ice-marginal zone (Line 4b, Fig. 23)
The Eidet site
The site (Locality A, Fig. 23) is located on the
distal slope of the Ra ridge complex, sheltered to
the north and east by rocky hills. The locality lies
120 m a.s.l. (65 m below the local ML). A sequence
of glaciomarine mud overlying diamiet sediments (flowtills) is described in detail, Fig. 24 (Rygg 1991). In
the lower part of the mud sediments ('near proximal
environment', Boulton 1990), three of five radiocarbon
dates give ages between 10.6--10.7 ka BP (Figs 24
and 25a). The diamict sequence represents the last
re-advance to the Ra. The mud unit II (Fig. 24) has
The Ski IMZ is a complex of mainly submarine
ice-marginal ridges (Kj~ernes, 1986; Bergstr~m, 1988;
Nordahl-Olsen, 1990). The correlation with Sweden
is discussed in detail by Lundqvist (1988, and also
in this volume). An oseiUation at the main ridge is
documented in two sections in the Oslofjord region as
well as in the valley of L~gen River (Fig. 23). Marine
shell-fragments in mud below diamictons in the main
Ski IMZ ridge has been dated to 10,170 ___ 190 BP
(S~arensen, 1983; Serensen et al., 1990). this is the only
date available, but indirectly a few other radiocarbon
dates support a late Y.D. age of this ice-marginal
complex.
166
B . G . Andersen et al.
ka
.6
tl.
$
a
,..
~
- ............................
1
=_.
0
•
¢0
........................................................................................
11
o
a
0
12
I
I
r
I
-
I
i
0
I
r
50 km
____]"
b
i
I
I
I
0
[
I
[
I
I
50 krn
FIG. 25. Recession diagrams for the eastern (a), and western side (b) of the Oslofjord (see Fig. 23). Revision of the diagram.presented
by S~rensen (1979), based on available radiocarbon dates. Diamonds: radiocarbon dates made on marine molluscs. *Average of three
dates from the Eidet locality (Locality A on Fig, 23), see Fig. 24, Circles: radiocarbon dates made on marine or limnic gyttja. Arrows
indicate obviously too old gyttja dates (cf. Olsson, 1979).
Early Preboreal/the Aker ice-marginal zone (Line 5,
Fig. 23)
The Aker IMZ consists of 3-4 ice-marginal ridges
below ML, developed as diamict-dominated ridges near
Oslo (Isachsen, 1941), ice-contact underwater fans in
Lier (Follestad, 1986; L0nne, 1993), ice-contact deltas,
and outwash fan/dead-ice wasting zones at Kongsberg
(JCrgensen and Sorensen, 1979). Above the ML small
push-moraine ridges are developed in some areas
(Gjessing, 1980). The age of the Aker IMZ has been
discussed by (Gjessing and Spjeldn~es, 1979; S0rensen,
1979, 1983). New dates presented by Henningsmoen
and Spjeldn~es (1991) confirm previous assumptions of
an Early Preboreal age (about 9.8 ka BP) of the
Aker IMZ.
Deglaciation chronology of the Oslofjord region
The main pattern and chronology of the deglaciation
has been known for a long time (cf. Holtedahl, 1960;
Andersen, 1965). However, during the last decades a
fairly large number of new radiocarbon dates have been
obtained. Nearly all of them are of marine molluscs,
and they are corrected for a 'reservoir age' of 440 or
410 years, which is possibly too small, see p. 158.
167
Ice-marginal Deposits in Norway
A few gyttja datings (of limnic sediments) are
available, and they correspond fairly well to the
established chronology based on marine mollusc dates
(within two standard deviations of the dates).
Glacial Recession and Oscillations (Fig. 25)
The position of the projection lines (I and II, Fig. 23),
has been chosen on the basis of the dominant glacier
movements during the time-span discussed. However, a
marked change in glacier movement occurred between
Late Allered and Early Y.D. on the west side of the
Oslofjord (S~arensen, 1992a), and this will introduce
some errors in the calculation of recession rates during
the AllerOd chron. This presentation shows just an
average trend for the Oslofjord region, and is the first
revision of the diagram presented by Serensen (1979).
It is based on all available radiocarbon dates published
later than 1964 and on recent unpublished dates.
Average recession rates are given in Table 1. From
Older Dryas (O.D.) to Y.D. the recession pattern is
similar on both sides of the Oslofjord, mainly due to
a similar glacier regime (Serensen, 1990, 1992a). The
major re-advance to the Ra IMZ is estimated to 6--7
and 10 km on the eastern and western side of the
Oslofjord, respectively. However, the estimates are
rather speculative as yet. The final retreat from the
Ra ridges to the As/Ski ice-marginal deposits was very
rapid on both side of the fjord during the interval from
ca. 10.6 to ca. 10.4 ka BP, with decreasing recession
rates at the end of the time-interval. At the end of Y.D.
the recession rates were very low and details cannot
be shown in the diagrams. Particularly on the eastern
side of the Oslofjord a pattern of small moraines
demonstrates the slow, stepwise glacier-retreat at the
end of Y.D (Rosenfeld, 1978; in S¢rensen, 1983). At
the transition from Y.D. to Preboreal the recession
rates increased rapidly, with a brief interval of glacierfront oscillations along the Aker IMZ.
TABLE 1. Average recession rates (in m yr-t) on both sides of
the Oslofjord. Hvaler-Onsey-The Ra Re-advance *As Ski-Tjeme
Slagen Goverud
Projection line I:
Projection line II:
35
35
15
20
60
30
90
95
6
-t
*Assumed values
tThe As IMZ is not identified
Recession diagram L for the eastern side of the
Oslofjord
'The J~imtland ice lobe' controlled the glacier regime
on the eastern side of the Oslofjord as well as southern
V~irmland and Dalsland in Sweden, during the Late
Glacial. Early Y.D. ice-front oscillations in southwest
Sweden are discussed by Bj6rck and Digerfeldt (1984,
1986), Johansson (1982), and Lind (1983).
No direct evidence on the magnitude of the Y.D.
glacier-front oscillations is found on the eastern side
of the Oslofjord, and the information from Sweden is
applied in the diagram.
Recession diagram H for the western side of the
Oslofjord
During Y.D. the glacier regime on the western side of
the Oslofjord changed considerably. This is explained
by the activation of 'The Hardangervidda-Jotunheimen
ice lobe' originating from 'The HardangerviddaJotunheimen glacier culmination zone' in central
Norway (Vorren, 1977; SOrensen, 1983). Evidence for
a strong re-advance to the Ra IMZ is the crushed marine
shells in clayey diamictons which are common in the Ra
from Horten to Krager¢, and the radiocarbon dated
sites 'behind' the Ra (Serensen, 1992a) and sub-till
AllerOd deposits (Bergstrem, 1994 manuscript).
REFERENCES
Aarseth, I. and Mangerud, J. (1974). Younger Dryas endmoraines
between Hardangerfjorden and Sognefjorden, Western Norway.
Boreas, 3, 3-22.
Andersen, B.G. (1954). Randmorener i sCrvest Norge. Norsk
Geografisk Tidsskrift, 14, 279-342.
Andersen, B.G. (1960). SCrlandet i Sen- og Postglacial Tid. Norges
Geologiske Undersckelse, 210, 1-142.
Andersen, B.G. (1965). The Quaternary of Norway. In: Rankama,
K. (ed.), The Quaternary 1, pp. 91-138. John Wiley, London.
Andersen, B.G. (1968). Glacial Geology of Western Troms, North
Norway. Norges Geologiske Undersckelse, 256, 1-160.
Andersen, B.G, (1975). Glacial Geology of Northern Nordland,
North Norway. Norges Geologiske Undersckelse, 320, 1-74.
Andersen, B.G., B6en, F. and Rasmussen, A. (1982). The Tj6tta
glacial event in southern Nordland, North Norway. Norsk
Geologisk Tidsskrift, 62, 39-49.
Anundsen, K. (1972). Glacial chronology in parts of southwestern
Norway. Norges Geologiske Undersckelse, 280, 1-24.
Anundsen, K. (1977). Radiocarbon datings and glacial striae
from the inner part of Boknfjord area, South Norway. Norsk
Geografisk Tidsskrift, 31, 41-54.
Anundsen, K. (1985). Changes in shore-level and ice-front position
in Late Weichsel and Holocene, Southern Norway. Norsk
Geografisk Tidsskrift, 39, 205-225.
Bargel, T.H. (ed.), Bergstr6m, B., Hilmo, B.O., Olsen, L.,
Storr¢, G. and Sveian, H. (1994). Guide til Midtnordenekskursjonen 1994. Kvart~ergeologl og milj¢geologi i Midt-Norge.
Norwegian Geological Survey Report, 94.071, 1--60.
Bergstr¢m, B. (1988). Siljan, Quaternary geological map. 1713-I,
scale 1:50 000 with description (in Norwegian). Norges Geologiske
Undersekelse, Skrifter, 86, 1-44.
Bergstrem, B. (1993). Isfrontvariasjoner i Nedre Telemark under
Aller~ad og Yngre Dryas. Geonytt 20, 15.
Bergstrem, B. (1994). Vikna-Kolvereid, in Bargel et al. 1994.
Bergstrem, B. (in preparation). Stratigraphical evidence of a
considerable Younger Dryas glacier advance in southeastern
Norway.
BergstrOm, B,, Olsen, K.S. and Serensen, R. (1992). Tjeme,
Quaternary geological map. 1813 II, scale 1:50 000 with
description on the map (in Norwegian). Norges Geologiske
Undersokelse.
Birks, H.H., Pans, Aa., Svendsen, J.I., Aim, T., Mangerud, J.
and Landvik, J. (1994). Late Weichselian environmental change
in Norway, including Svalbard. Journal of Quaternary Science, 9,
133-145.
Bj6rck, S. and Digerfeldt, G. (1984). Climatic changes at
Pleistoeene/Holocene boundary in the Middle Swedish end
moraine zone, mainly inferred from stratigraphic indications.
In: M6rner, N.-A. and Karl~n, W. (eds), Climatic Changes
on a Yearly to Millennial basis, pp. 37-56. Reidel Publishing
Company, Dordrecht.
Bj6rck, S. and Digerfeldt, G. (1986). Late Weichselian-Early
Holocene shore displacement west of Mt. Billingen, within the
Middle Swedish end moraine zone. Boreas, lg, 1-18.
Bjerlykke, K.O. (1990). Lidt om Aas-Mor~enen. Tidsskrfit for Det
norske landbrug 7. Christiania.
Blystad, R. and Anundsen, K. (1983). Late Weichselian Stratigraphy
at Hielmeland, Southwest Norway. Norsk Geologisk Tidsskrift,
63, 277-287.
168
B.G. Andersen et al.
Boulton, G.S. (1990). Sedimentary and sea level changes during
glacial cycles and their control on giacimarine facies architecture.
In: J.A. Dowdeswell and J.D. Scourse (eds), Glacimarine
Environments: Peocesses and Sediments, pp. 15-52. Geological
Society Special Publication 53, London.
Brandai, M.K. and Heder, E. (1991). Stratigraphy and sedhnentation
of a terminal moraine deposited in a marine environment - - two
examples from the Ra-ridge in Ostfold, southeast Norway. Norsk
Geologisk Tidsskrift, 71, 3-14.
Dahl, S.O. and Nesje, A. (1992). Paleodimatic implications based
on equilibrium-line altitude depressions of reconstructed Younger
Dryas and Holocene cirque giaciers in inner Nordfjord, Western
Norway. Palaeogeography, Palaeoclimatology, Palaeoecology, 94,
87-97.
Dahl, A., Olsen, K.S. and Serensen, R. (in press). Holmestrand,
Quarternary geological map. 1813 IV, scale 1:50 000 with
description on the map (in Norwegian). Norges Geologiske
Undersekelse.
Fareth, O.W. (1987). Glacial geology of Middle and Inner
Nordfjord, western Norway. Norges Geologiske Undersekelse,
408, 1-55.
Follestad, B.A. (1972). the delgaciation of the south-western parth
of the Folgefonn Peninsula, Hordaland. Norges Geologiske
Undersekelse, 280, 31--64.
Gjessing, J. (1980). The Aker moraines in southeast Norway. Norsk
Geografisk Tidsskrift 34, 9-34.
Gjessing, J. and Spjeldnaes, N. (1979). Dating of the Grefsen
moraine and remarks on the deglaciation of southeast Norway.
Norsk Geografuk Tidsskrift, 33, 77--81.
Henningsmoen, K.E. and Spjedn~es, N. (1991). Kvart~erdateringer
fra SkAdalen ved Oslo. Abstract in Geonytt 18, 26.
Holtedahl, O. (1960). Geology of Norway. Norges geologiske
undersekelse, 208, 1-540.
Hoitedahl, H. (1964) An Allered Fauna at Os, near Bergen,
Norway. Norsk Geologisk Tidsskrift, 44, 315-322.
Holtedahl, O. (1974). Noen giasifluviale isrand-avsetninger i den
sydlige delav Glomma-vassdragets (n~tv~erende)dreneringsomr~ide.
Norges Geologiske Undersokelse, 306.
Holtedahl, H. (1975). The Geology of the Hardangerfjord, West
Norway. Norges Geologiske Undersekelse, 323, 1-87.
Isachsen, F. (1941"). Grefsenmorenens opbygning og fossilinnhold.
Norsk Geologisk Tidsskrfit, 20, 253-262.
Johansson, B.T. (1982). Degiaciationen av Norra Bohnsl/in och
S6dra Dalsland. University Gothenburg, Department Geological
Publication A 38, 180 pp.
Jergensen, P. and Serensen, R. (1979). Late Glacial and Holocene
deglaciation and sedimentation in L~tgendalen, southeastern
Norway. Norsk Geologisk Tidsskrfit, 59, 337-343.
Kaldhol, H. (1930). Sunnmores kvart~ergeologi. Norsk Geologisk
Tidsskrift, 11, 1-194.
Kj~ernes, P.A. (1986). Askim, Quaternary geological map. 1814-11,
scale 1:500 00. Norges Geologiske Undersokelse.
Kj~rnes, P.A. (1984) Sarpsborg, Quaternary geological map. 1913I, scale 1:50 000. Norges Geologiske Undersekelse.
Klakegg, O. (1991). Drammen, Quaternary geological map. 1814III, scale 1:50 000, with description on the map (in Norwegian).
Norges Geologiske Undersekelse.
Klakegg, O. and Nordahl-Olsen, T. (1985). Nordfjordeid. Beskrivelse
til kvartaergeologisk kart 1218 I-M 1:50 000. Norges Geologiske
Undersokelse, 71, 1-29.
Klakegg, 0., Nordahl-Olsen, T., Senstegaard, E. and Aa, A.R.
(1989), Sogn og Fjordane, kvart~ergeologisk kart, M 1:250 000.
Norges Geologiske Undersekelse.
Klakegg, O. and Serensen, R. (1991). Horten, Quaternary
geological map. 1814-Ill, scale 1:50 000, with description on
the map (in Norwegian). Norges Geologiske Undersekelse.
Larsen, E., Eide, F., Longva, O. and Mangerud, J. (1984).
Allered-Younger Dryas climatic inferences from cirque glaciers
and vegetational development in the Nordfjord area, Western
Norway. Arctic and Alpine Research, 16, 137-160.
Lind, B. (1983). Deglaciation och h6gsta kustlinjen i Norra Dalsland.
University Gothenburg, Department Geological Publication A 43,
175 pp.
Lundqvist, J. (1988). Younger Dryas-Preboreal moraines and
deglaciation in southwestern V/irmland, Sweden. Boreas, 17,
301-316.
Lenne, I. (1993). Sedimentology of an Early Holocene ice-contact
submarine fan influenced by syndepositional glaciotectonic
deformation: Egge-LyngAs, Southern Norway. In: Lenne, I.
(ed.), Sedimentology of Marine Ice-contact Systems in Fjords.
Dr. Scient. Thesis, University of Troms¢.
Mangerud, J. (1970). Late Weichselian vegetation and icefront
oscillations, in the Bergen district, Western Norway. Norsk
Geograf~k Tidsskrift, 24, 121-148.
Mangerud, J. (1977). Late Weichselian marine sediments containing
shells, Foraminifera and pollen, at Agotnes, western Norway.
Norsk Geologisk Tidsskrift, 57, 23-54.
Mangerud, J. (1980). Ice-front variations of different parts of the
Scandinavian Ice Sheet, 13,000--10,000 Years BP. In: Lowe, Gray
and Robinson (eds), The Late Glacial of North-West Europe.
pp. 23-30. Pergamon Press.
Mangerud, J., Larsen, E., Longva, O. and Senstegaard, E. (1979).
Glacial history of western Norway 15,000-10,000 B.P. Boreas, 8,
179-187.
Mangerud, J., Lie, S.E., Fumes, H. Kristiansen, I.L. and I.~mo, L.
(1984). A Younger Dryas ash bed in western Norway, with
possible correlations to Norwegian Sea and the north Atlantic.
Quaternary Research, 21, 85-104.
Marthinussen, M. (1961). Brerandstadier og avsmeltningsforhold i
Rappart]ord-Stabbursdal-omrAdet, Finnmark. Norges Geologiske
Undersekelse, 213, 118-169.
Marthinussen, M. (1962). 14C-datings referring to shore line,
transgressions, and glacial substages in Northern Norway. Norges
Geologiske Undersckelse, 215, 37-67.
Marthinussen, M. (1974). Contributions to the Quaternary Geology
of North-easternmost Norway and closely adjoining foreign
Territories. Norges Geologiske Undersekelse, 315, 1-157.
Nesje, A. and Dahl, S.O. (1992). Equilibrium-line altitude
depressions of reconstructed Younger Dryas and Holocene
glaciers in Fosdalen, inner Nordfjord, Western Norway. Norsk
Geologisk Tidsskrift, 72,209-216.
Nesje, A. and Dahl, S.O. (1993). Lategiacial and Holocene glacier
fluctuations and climate variations in Western Norway: a review.
Quaternary Science Reviews, 12, 255-261.
Nilsen, D.E. (1978). En kvart~ergeologisk undersekelse i
Sandefjordistdktet. University of Oslo, Unpublished Thesis,
136 pp.
Nordahl Olsen, T. (1990). Ski, Quaternary geological map. 1914III, scale 1:50 000, with description (in Norwegian). Norges
Geologiske Undersekelse, Skrifter, 95, 1-33.
Olsen, K.S. and Lewe, A. (1984). Sandefjord, Quaternary geological
map. 1813-III, scale 1:50 000. Norges Geologiske Undersekelse.
Oisson, I.U. (1979). A warning against radiocarbon dating of
samples containing little carbon. Boreas, 8, 203-207.
Rasmussen, A. (1981). The deglaciation of the coastal area NW
of svartisen, Northern Norway. Norges Geologiske Undersekelse,
369, 1-31.
Reite, A.J. (1968). Lokalglaciasjon pA Sunnmere. (On the mountain
glaciation of Sunnmere, West Norway.) Norges Geologiske
Undersekelse, 247, 262-287.
Reite, A.J. (1994). Weichselian and Holocene geology of S~r
Trendelag and adjacent parts of Nord Trondelag county, central
Norway. Norges Geologiske Undersekelse, 426, 1-29.
Reite, A.J., Seines, H. and Sveian, H. (1982). A proposed
deglaciation chronology for the Trodheimsfjord area, central
Norway. Norges Geologiske Undersokelse, 373, 75-84.
Rosenfeld, H.J. (1978). Israndavsetninger i omrAdet Vestby-Ski.
Department of Geology, Report 6, 1-21. Agricultural University
of Norway.
Rye, N., Nesje, A., Lien, R. and Anda, E. (1987). The Late
Weichselian ice sheet in the Nordfjord-Sunnmere area and
deglaciation chronology for Nordfjord, Western Norway. Norsk
Geografisk Tidsskrift, 41, 23-43.
Rygg, A. (1991). Litostratigrafi og biostratigrafi i et snitt i Raet
ved Eidet i Ostfold. 147 pp. Unpublished Thesis, University of
Oslo.
Sollid, J.L., Andersen, S., Hamre, N., Kjeldsen, O., Salvigsen, O.,
Stur6d, S., TveiterA, T. and Wiheimsen. A. (1973). Deglaciation
of Finnmark, North Norway. Norsk Geologisk Tidsskrift, 27,
233-325.
Sollid, J.L. and SOrbel, L. (1975). Younger Dryas ice-marginal
deposits in Trendelag, Central Norway. Norsk Geografisk
Tidsskrift, 29, 1-9.
Sollid, J.L. and Serbel, L. (1979). Deglaciation of Western Central
Norway. Boreas, g, 233-239.
Sollid, J.L. and S~rbel, L. (1982). Kort beskrivelse til glacialgeologisk
kart over Midt-Norge 1:500 000. Norsk Geografisk Tiddskrift 36,
225-232.
Ice-marginal Deposits in Norway
Sveian, H. (1989). Stildestad. KvarUergeologisk kart 1722-IV
M:1:50 000. Norges C-eologiske Unders~keise, Skrifter, 89, 1-54.
Sveian, H. (1994). KvartJergeologi i Midt-Norge, in Bargel et al.,
1994.
Sveian, H. (/n preparation). Beskrivelse til kvartsergeologisk
fylkeskart Nord-Tr~ndelag M: 1:250 000. Norges Geolo$iske
Unders~kels.
S~rensen, R. (1979). Late Weichsellan degiaciation in the Oslot]ord
area, south Norway. Boreas, 8, 241-246.
S~remen, R. (1983). Glacial deposits in the Oslofjord area. In:
Ehlers, J. (ed.), Glacial Deposits in North-west Europe, pp. 19-27.
Balkema, Rotterdam.
SCrensen, R. (1990). The Aller~l-Younger Dryas biological and
glacial environment in the Oslofjord area, southeastern Norway.
Abstract In: Lundqvist, R. and Saarnisto, M. (eds), Termination
of the Pleistocenc IGCP-253 Field Conference.ExCursion and
Abstracts, pp. 143--144.
169
Sorensen, R. (1992a). The physical environment of Late Weichselian
degiaciation of the Oslofjord region, southeastern Norway.
Sveriges Geologiska UndersOkning. Set. Ca 81,339-346.
SCrensen, (1992b). NORDQUA-IGCP 253 excursion on the
western side of the Oslofjord, 29 September 1992. Field guide,
20 pp.
S~rensen, R., Lie, K.T. and Nybakken, S.E. (1990). DrCbak,
Quaternary geological map. 1814-II, scale 1:50 000 with
description on the map (in Norwegian). Norges Geologiske
Undersokelse.
Undls, I. (1963). Ra-morenen i Vest-Norge. J.W. Eides Boktrykkeri
A.S. Bergen.
Vorren, T. (1977). Weichselian ice movements in south Norway
and adjacent areas. Boreas, 6, 247-257.
Ovstedal, D.O. and Aarseth, I. (1975). Bryophytes from Late
Weichselian sediments at Vinnes, Western Norway. Lindbergia,
3, 61--68.