Thursday, June 4, 2020

Convergent-Plate Margins - Olympic National Park, WA

Olympic National Park

I visited Olympic National Park near Seattle, Washington. The park consists of the Olympic Mountain Range including Mt. Olympus. This is a coastal mountain range resulting from a convergent-plate margin. Specifically, the Juan de Fuca plate (oceanic) is sliding under the North American Plate (continental). In addition, the Pacific plate and Juan de Fuca plates are divergent, moving away from each other to constantly form new crust in the Pacific Ocean off of Washington’s coast. 
            The Olympic Mountain Range is made by thrust faulting where the oceanic floor and crust is pushed up slowly forming mountains. These are made up of oceanic sediments and hard rock, as well as pillow lava, which was formed from magma cooling underwater. The mountains also consist of large piles of basalt which are pushed upwards. Folding and Faulting contribute to these mountains. 
            Parallel to the Olympic Mountains lies another mountain range, The Cascade Range. While the Olympic Mountains lie on top of the Cascadia Subduction Zone, the Cascade Range lies further inland where the Juan de Fuca plate is deeper beneath the North American plate. At this depth, the plate releases hot water which heats and melts the earth. This creates magma which moves up to the surface creating the volcanic Cascade mountain range. In between these two ranges is the Puget sound which lies almost completely at sea level. 
folding




pillow lava

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