Washington
Washington
10,000 year old glaciated land
Nor
e
s
tain
oun
g
al Ran
M
ade
asc
th C
Coast
Basalt lava
Plateau
Rivers of Washington
Excellent drainage patterns and a through-flowing river
No tin or iron
Farm Land
Volcanoes in
Washington
http://www.dnr.wa.gov/Publications/ger_
ftg1_yakima_valley_wine_country.pdf
Geological Provinces of Washington
Northern Cascade
Mountains
c Ca
scad
e Mo
unta
ins
Olympic
Peninsula
Volc
ani
Now to the continental glacier
Wisconsin Age Glacier footprint
max 17,000 years ago
Washington
Northern Cascades
nd
ou
tS
ge nd
Pu wla
Lo
High
Willapa Hills
Casc
ades
Tramping the Willapa (WILL-ə-pah) Hills Geological Province
Cross Section: W-E Central Washington
Cross Section: W-E Central Oregon
12,92
0
Recent Glacial
sand & gravel
Oceanic
basalt
0
10,80
’
Dry Holes
’
Willapa Hills
Conclusions:
Either a geosyncline in early
stages of crushing
Or an exotic terrain being
welded onto Washington
Detail around Castle Rock
Recent Glacia Debris
Recent Volcanic Basalt
Deep Ocean Shales & Sands
Deep Ocean Basalt
Deep ocean shales
40 million years old
What rocks lie below the basalt?
Deep ocean lavas
40 million years old
13.000 foot
dry hole here
Eardley shows 15,000 feet
of sandstones & shales
High
Willapa Hills
Casc
ades
Northern Cascades
Willapa Hills (north half)
Area of next 5 slides
Area of Previous slides
40 million years old
oceanic basalts
Willapa Hills (north half)
40 million years old
marine sd & sh
40 million years old
oceanic basalts
Willapa Hills (north half)
30 million years old
marine sd & sh
40 million years old
marine sd & sh
40 million years old
oceanic basalts
10 million years old
marine sd & sh
30 million years old
marine sd & sh
40 million years old
marine sd & sh
40 million years old
oceanic basalts
Willapa Hills (north half)
Recent glacial
debris
10 million years old
marine sd & sh
30 million years old
marine sd & sh
40 million years old
marine sd & sh
40 million years old
oceanic basalts
Next, a West-East Cross Section
40 million year old oceanic crust?
OR
Thick 40 million year old sandstones & shales
below a marine basalt lava flow?
Willapa Hills (north half)
Location of a West-East Cross Section
Cross Section
Willapa Hills
(North half)
40 million year old oceanic crust?
What’s all this rock?
Thick trench (geosyncline?) filling but
not under oceanic crust!!!
Space Images of Willapa Hills
Space Images of Willapa Hills
Focus of Basalt Areas
Washington: Topography
Willapa Hills
http://wa_geology.home.comcast.net/~wa_geology/
Submarine canyons cut by
glacier melt rivers
Columbia River canyon
Willapa Hills
Willapa Hills: Topography
Willapa Hills
Next, the Columbia River
Looking East at the mouth of the Columbia River
Narrow flood plain on the Columbia
Flood plain & weather hill farming
Oregon foreground, Washington across the Columbia
Willapa clearcutting
Clear-cut Logging: Willapa Hills
Next: the Puget Sound Lowlands
Most Recent Continental Glaciation
100,000 to 17,000 years ago
Notice that glaciers extend
well out into the Pacific Ocean
How did First Nation People
get across Canada and into
the USA and Mexico?
The Glacial Footprint
Flooded valley excavated by
moving ice
The Glacial footprint in Washington
The Puget Sound Lowlands
Puget Sound
Lowlands
Olympic
Peninsula
Geologic Provinces of Washington
Puget Sound
Lowlands
Glacial “footprint”
Northern Cascades
High
Willapa Hills
Csca
des
Olympic
Peninsula
Lowlands and the surface rocks
Lowlands and the surface rocks
Wisconsin Age Glacier footprint
max 17,000 years ago
“Strong” Rocks “Weak” Rocks
A Broader Picture of
the Continental Glacier
A Broader Picture of the Continental Glacier
Area of
last slide
These colors
show the four
states
A Glacial Cartoon
Wisconsin Glaciation lasting from about 100,000 to 10,000 years
A Glacial Cartoon
Puget Sound lowlands
Puget Sound
Under Ice
glacier?
This is only the area of its
footprint if the ice over Seattle
was 3,412 feet deep!
Here’s what the glacier really looked like
What the glacier really looked like
Olympic Peninsula
mountains above
3.500 feet
Area of a glacier
3,200 feet thick
over Seattle
Movement of glacial ice
around the Olympic Mountains
What glaciers leave behind
What glaciers leave behind
Glacial Erratics
Glacial Striations
Glacial Loess
(wind blown dust)
Now the Olympic Peninsula
http://www.ecy.wa.gov/programs/sea/pugetsound/tour/geology.html
The Amazing Olympic Peninsula
Olympic
Peninsula
Geologic Provinces of Washington
Northern Cascades
Puget Sound
Lowland
High
Willapa Hills
Csca
des
Olympic
Peninsula
The Unique Structure of the Olympic Peninsula
The Unique Structure of the Olympic Peninsula
Geologic Map
Olympic
Peninsula
The Geological Unique History of
the Olympic Peninsula
Marine basalt lava flows
(folded and steeply dipping)
Marine basalt lavas here are “flat lying”
The Geological Unique History of
the Olympic Peninsula
Ocean water
Sands & clay debris from
eroding North America
Where did the oceanic basalt and
deep sea sediments come from?
The Oceanic Plate Subduction Theory
The Geological Unique History of
the Olympic Peninsula
Creates a landscape like Willapa Hills
Slic
i
ng
the
geo
syn
clin
e
The Oceanic Plate Subduction Theory
The Geological Unique History of
the Olympic Peninsula
Compressing & folding the rocks
Note: no rock melting into lavas
The end result: A cartoon
The Oceanic Plate Subduction Theory
The Geological Unique History of
the Olympic Peninsula
Plate Subduction theory: Pacific oceanic
plate over ridden by the North American
continental plate.
Another Theory to explain the rocks
of the Olympic Peninsula
Exotic Terraine-Island Arc Theory
Island Arc moving east
North American
continent
moving west
http://www.washington.edu/burkemuseum/geo_history_wa/The%20Omineca
%20Episode.htm
Exotic Terraine-Island Arc Theory
Second Island Arc
approaching
North America
First Island Arc
welded onto
North America
http://www.washington.edu/burkemuseum/geo_history_wa/The%20Omineca
%20Episode.htm
million years Arc
ago Theory
Exotic50
Terraine-Island
Several Island Arcs
have been welded
onto North America
http://www.washington.edu/burkemuseum/geo_history_wa/The%20Omineca
%20Episode.htm
million years Arc
ago Theory
Exotic30
Terraine-Island
The finale
http://www.washington.edu/burkemuseum/geo_history_wa/The%20Omineca
%20Episode.htm
Exotic Terraine-Island Arc Theory
The Several Accretionary Island Arcs
What does the Olympic Peninsula
actually look like?
A sketch map showing our interpretation of the original extent of the Terrane
Belts extending into Washington. The southern end of the belts is covered by
younger rock of the Columbia Plateau. This is our “best guess” at the original
southern extent of the terranes.
http://www.washington.edu/burkemuseum/geo_history_wa/The%20Omineca
%20Episode.htm
Olympic Peninsula Landscapes
Sedimentary sandstones
and shales dipping
vertically and forming
rugged mountains
Olympic Peninsula Landscapes
Mt. Carrie
http://en.wikipedia.org/wiki/Olympic_Mountains
Olympic Peninsula Landscapes
Olympic Peninsula Landscapes
Olympic Peninsula Landscapes
Olympic Peninsula Natural Resources
Our vagabond route
ades
Timber
High
Casc
Now, the High Cascade Mountains
Note: No metals in the
High Cascades
Our vagabond route
Northern Cascades
High
Willapa Hills
Casc
ades
The Broader Picture of the High Cascades
The Broader Picture of the High Cascades
High Cascades
High Cascades
Active Volcanoes
in North America
http://vulcan.wr.usgs.gov/Volcanoes/WesternUSA/M
aps/map_potentially_active.html
asca
de
High
C
Mt. Ste Helens
Rang
e
Mt Rainer
Mt. Adams
High
Casc
ades
Mt. Rainier
Mt. St. Helens
Mt. Adams
Mt. St. Helens
Mt. St. Helens & Mt. Adams
Mount St Helens
Mount Adams
Mt. St. Helens
The 1980 eruption of Mount St. Helens, a stratovolcano located in
Washington state, in the United States, was a major volcanic eruption. The eruption
(which was a VEI 5 event) was the only significant one to occur in the contiguous 48
U.S. states since the 1915 eruption of Lassen Peak in California
Mt. St. Helens
May 1980
8:32 a.m. on May 18, 1980
May
19,High
1982 Cascades
Now the rocks of
the
9 am May 17 1980
Hig
hC
asc
ade
s
Geologic Map: Washington
Geologic Map: Washington
High Cascades
Volcanic Rocks
3 million years old
lesser amounts of hornblende
Andesite lava: melted geosynclinal shales?
Andesite is a gray to black volcanic rock with between about 52 and 63 weight percent\
silica (SiO2). Andesites contain crystals composed primarily of plagioclase feldspar
and one or more of the minerals pyroxene and lesser amounts of hornblende
Andesite magma commonly erupts from stratovolcanoes
as thick lava flows, some reaching several km in length. Andesite magma can also
generate strong explosive eruptions to form pyroclastic flows and surges and enormous
eruption columns. Andesites erupt at temperatures between 900 and 1100° C
Geologic Map: Washington
High Cascades
Volcanic Rocks
3 million years old
Geologic Map: Washington
High Cascades
Volcanic Rocks
1 million years old
Geologic Map: Washington
High Cascades
Present day active
volcanoes adding
more lava to the
older lavas of the
High Cascades
North America During the Last Billion Years
Volcanic Rocks in the High Cascades
Cretaceous Period
Cross Section: High Cascades
Three Ages of Felsic* Lava Flows
Lavas here in the
Willapa Hills are
Oceanic crust
Where did all this molten rock come from?
There must be a “furnace” melting deeply buried rock
Felsic lavas: having
thecrust
chemical
composition
of
Oceanic
below the
“felsic” furnace!
continental crust
The Northern Cascades
Northern Cascades
High
Willapa Hills
Casc
ades
plutonic & metamorphic rocks
Washington: Topographic Map
Northern Cascades
asca
de
High
C
Mt. St Helens
Rang
e
Mt Rainer
Mt. Adams
The Geologic Map: Washington
Geologic Map: Washington
Northern Cascades
Area of complex
*plutonic igneous &
I
metamorphic
rocks
Rocks: more of
the same
High Cascades
*Plutonic: created at great depth
Natural Resources: Washington
Metamorphic rocks; natural ore resources
Briefly, on the complex geology
Igneous Rocks of Northern Washington
Area of complex plutonic
igneous and metamorphic rocks
Igneous Rocks not along
the Cascade Trend
Okanogan
Subcontinent
Okanogan Subcontinent
Metamorphic
Rocks
Granite
North
American
Continent
Metamorphic
Rocks
First,
lookexplain
at the “basement”
Howlet’s
do we
the vast
rocks
in
the
neighboring
area
of
difference
in
the
age
of
the
Okanogan Subcontinent; age 100 million years plus or minus
thetwo
North
Cascade
Subcontinent
“basement”
rock
areas?
North American
continent;
age of “basement”
granites
&
metamorphic rocks here, 2 billion years plus or minus 200 million years
North Cascade Subcontinent
Area of “Basement” Plutonic
Igneous and Metamorphic Rocks
North Cascade Subcontinent
ak
e
P
Metamorphic rocks
like continental crust
ier
c
Major Cascade volcano last
Gla
eruption 12,000 years ago
Granite
Metamorphic
*Peridotite
Rocks
How do we explain the vast
difference in the age & rock type
of these “basement” rock areas?
* Peridotite: igneous rock like Oceanic Crust
Granite: igneous rock like Continental Crust
Explaining?: the “Basement” Rock
Areas of Northeastern Washington
North Cascade Subcontinent
100 million years old, mixture
of igneous & metamorphic
rocks of both continental
and oceanic crust types
Okanogan
Subcontinent
100 million years old
Igneous & metamorphic
rocks like continental
crust
Rocks are the deformed margin
f the North American continent
North
American
Continent
2 billion years old
Continental crust
of North America
2. Rocks were “rafted-in” from the west
And here Permian Rocks:
250 million years ago
Not here
But remember this one
in Idaho and eastern
Oregon & Washington
2. Rocks were “rafted-in” from the west
The Generally Accepted Explanation
North Cascade
Subcontinent
North
American
Continent
Okanogan
Subcontinent
1. Rocks are the deformed margin
of the North American continent
We’ll explore explanation #1 when
we’ve looked at Western Canada
The Columbia Plateau
Northern Cascades
Columbia Plateau
Multiple *Basalt lava flows
High
Willapa Hills
Casc
ades
plutonic & metamorphic rocks
*Basalt lava flows: similar rock
to Oceanic Crust
Columbia Plateau Basalt Lava Flow
Multiple lava flows
About 4 million years old
Similar to oceanic crust
What rocks were covered by the basalt?
Exotic subcontinents
rafted in from the Pacific
<100 million years old
Cross Section
Nor
t
Con h Am
er
t
1–2 inenta ican
l
bill
ion Crust
yea
rs o
ld
Rocks Thought to be Below the Basalt
4 million year old
Columbia Basalt
lava flows
Plateau Basalt lava flows
Northern Cascades: granite &
metamorphic rocks
Deep oceanic sediments
Okanogan
subcontinent
Exotic subcontinents
rafted in from the
Pacific
Cross
Section
<100 million years old
Nor
t
Con h Am
er
t
1–2 inenta ican
l
bill
ion Crust
yea
rs o
ld
Rocks Thought to be Below the Basalt
4 million year old
Columbia Basalt
lava flows
Plateau Basalt lava flows
Oldest Exotic
Pacific terrane
North American
Continental Crust
1–2 billion years old
Exotic subcontinents
rafted in from the Pacific
<100 million years old
Nor
t
Con h Am
er
t
1–2 inenta ican
l
bill
ion Crust
yea
rs o
ld
The Source for the Lava Flows of Washington
4 million year old
Columbia Basalt
lava flows
Cross Section
Source area
for basalt lavas
Permian Rocks:
250 million years ago
Not here
Source of the basalts of
Oregon & Washington
Source of Lava Flows; SE Washington
Younger Exotic
Pacific terranes
Oldest Exotic
Pacific terrane
North American
Continental Crust
1–2 billion years old
On the British Columbia
Source of Lava Flows; SE Washington
Oldest Exoticevent shaping
The
final geological
Younger Exotic
Pacific terrane
Pacific terranes
the landscape of Washington
North American
Continental Crust
1–2 billion years old
Melting of the recent continental
glacier about 10,000 years ago
http://hugefloods.com/Basalt.html
Melting of the recent continental
glacier about 10,000 years ago
A more regional map
Columbia Scab Lands
canyon complex carved
by glacial lake melt water
Earlier glacial
Lake Missoula
Canyons (scabland) created
by glacial lake flood waters
Glacial
Lake Spokane from
the previous slide
http://www.uwsp.edu/geo/projects/geoweb/
participants/Dutch/VTrips/Scablands0.HTM
Location of the Scablands
These basalt canyons provide evidence that giant floods thousands of years ago did
the brunt of the work required to create this canyon.
Natural Resources: Washington
Scablands
North Border of Scablands
Looking North
Columbia River upper background
Scablands ‘”coulees” gray
Farm land: flood plains
Scabland Coulee
The floods left behind "coulees"—dry streambeds or gullies—all over what is now
eastern Washington. Here, an old homestead sits in the bottom of a coulee within the
"scablands," the term early settlers gave to the region's flood-scoured lands.
Sagebrush blankets the steep, flood-cut slopes, while above them wheat fields take
advantage of rich soils the floods didn't reach
Columbia River Basalt:
15 million years old
present day occurrence
Scablands
http://hugefloods.com/ColumbiaGorge.html