1. By: Theresa Zajac & John Solder
The Cascades
By: Theresa Zajac & John Solder

2. Geography & Climate Extends 700 miles N-S
Lassen Peak to Lytton Mountain
West Slope – 150 inches
East foothills – 9 inches
Temperate rain forest to alpine
Mount Rainier 14,411 ft

3. Geology Cascades- volcanics North Cascades Western Cascades
Eocene & Miocene
High Cascades
Pliestocene
North Cascades
Western
Greenschist facies Meta-sedimetary &Meta-volcanic (Paleozoic to Mesozoic formation and Paleogene metamorphism)
Metamorphic Core
Epidote-Amphibolite facies meta-volcanic and meta-sedimentary (Mesozoic)
Methow
Oceanic sandstones and shales (Mesozoic back-arc basin)

4. Tectonics
Juan de Fuca and Gorda plate subduction is source of modern volcanism and seismic activity.
N. Cascades trisected by N-S running faults.
Paleomagnetic data suggest rotation and northward movement of Cascades.

5. Crust and Lithosphere Oregon- high heat flow, >80 mW/m^2
Gao, 2011
Oregon- high heat flow, >80 mW/m^2
Wash.- low heat flow, <40 mW/m^2

6. Chronology 500-200 m.y.a - North Cascades plutons implaced
100 m.y.a –Farallon Plate begins subducting beneath N. America
90 m.y.a. –Terranes accreted onto N. America
36 m.y.a. - Cascade Range volcanism begins
5-7 m.y.a. – After lull in activity, Cascade volcanism resumes, forming High Cascades.
4-7 m.y.a – Juan de Fuca separates from Explorer plate, steeping subduction angle of Juan de Fuca, prompting the folding of the N American plate and uplifting of North Cascades
May 18, 1980 – 31 years ago – Mt. St. Helens ERUPTS!!!!