Cascade Volcanos
What is the age of the modern Cascades?
40 million years old
How thick are the flows in Ellensburg?
About 1/2 mile thick
What modern plate was once part of the Farallon plate?
The Juan De Fuca Plate.
When did Siletzia accrete to North America?
51-49 million years ago.
What are the two types of gold?
Wire/crystalline and nuggests/placer gold
What is the average lifespan of a Cascade volcano? (How long do they last for?)
2 million years
Where and how deep are the thickest parts of the basalt flows?
3 miles thick in the tri-cities.
40 million years ago, the entire west coast had what?
Volcanoes!
When did Siletzia form?
55 million years ago.
What is the name of the basalt found in the Liberty gold?
Teanaway Basalt
What was the largest Cascade eruption in the last 7700 years?
Mt. Mazama
How many individual basalt flows have there been?
About 300 different flows.
About 20 million years ago.
The Olympic Mountains of made of what two rocks?
Basalt and sedimentary rocks.
Age of the rocks the gold is found in?
49-59 million years old.
What are the four main volcanic products?
Ashfall, pyroclastic flow, lava flow, lahar. (Others are acceptable)
What geologic feature did the basalt flow out of?
Dikes/Fissures
Why did transform faults form from this?
Change of plate directions.
What happened to the subduction during Siletzias accretion? What happened after?
During, subduction stopped. After, the subduction zone moved farther out west.
What two rocks are the gold found in?
The Swauk formation and basalt.
Exposed intrusive igneous rocks.
What caused the basalt flows?
The doming of the Yellowstone hotspot.
What is the future of the Cascade volcanoes?
They will go extinct.
What is thought to of formed Siletzia?
The Yellowstone Hotspot.
What is the order of the layers for the Liberty gold?
Check later