GEO 120 Lecture Notes - Lecture 20: Mount Rainier National Park, Juan De Fuca Plate, Olympic National Park

• School: URI
• Department: Geosciences
• Course: GEO 120
• Professor: Elizabeth Laliberte

Document Summary

Geo 120 - lecture 20 - plate boundaries - elizabeth laliberte. Oceanic plate goes under the continental crust. Forms 2 parallel mountain ranges in the pacific northwest due to subduction. Coastal mountains formed by oceanic sediment and basalt scraped off subducting plate. Subducting plate dehydrates to form cascade volcanoes. Puget sound and the willamette valley are low-lying regions between the rising mountains. Olympic national park vs. mount rainier national park. Crescent terrane - basalt erupted on the seafloor and islands. Core area - sedimentary layers uplifted from the ocean floor. Glacial deposits - cover older sedimentary layers. Formed when magma flows through the oceanic crust to the surface and seeps through old pillow rocks. High-silica lavas produce a steep-sided composite volcano. Gray colors are due to andesite lava flows & volcanic mudflows (lahars) Glaciers erode mountains and provide water for lahars. Farallon plate is being subducted beneath the western edge of north america. Volcanic are extended from alaska to mexico.