Washington

Washington

Co

astal Ran

ge

No

rth C

ascade M

ou

ntain

s

Basalt lavaPlateau

10,000 year old glaciated land

Rivers of WashingtonExcellent drainage patterns and a through-flowing river

Farm Land

No tin or iron

http://www.dnr.wa.gov/Publications/ger_ftg1_yakima_valley_wine_country.pdf

Volcanoes inWashington

Geological Provinces of Washington

Vo

lcan

ic C

asca

de

Mo

un

tain

s

Northern Cascade Mountains

OlympicPeninsula

Now to the continental glacier

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?

Igneous Rocks of Northern Washington

Area of complex plutonic igneous and metamorphic rocks

Igneous Rocks not along the Cascade Trend

Permian Rocks: 250 million years ago

Not here

But remember this one in Idaho and eastern Oregon & Washington

And here

Hig

h C

asca

des

Northern Cascades

Willapa Hills

The Columbia Plateau

plutonic & metamorphic rocks

Columbia Plateau

Multiple *Basalt lava flows

*Basalt lava flows: similar rock to Oceanic Crust

Columbia Plateau Basalt Lava Flow

Multiple lava flows

About 4 million years old

Similar to oceanic crustWhat rocks were covered by the basalt?

The Source for the Lava Flows of Washington

Exotic subcontinents rafted in from the Pacific <100 million years old

4 million year oldColumbia Basalt lava flows

Cross Section

Source area for basalt lavas

No

rth

Am

eric

anC

on

tin

enta

l Cru

st

1–2

bill

ion

yea

rs o

ld

Permian Rocks: 250 million years ago

Not here

Source of the basalts of Oregon & Washington

North AmericanContinental Crust 1–2 billion years old

Oldest ExoticPacific terrane

Younger ExoticPacific terranes

Source of Lava Flows; SE Washington

On the British Columbia