NATS 1750 Lecture Notes - Lecture 18: Continental Crust, Aretes, Lithosphere
30 Dec 2019
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*key point: more snow falls than melts in the summer. Glaciers can develop in polar regions and on mountains at any latitude. The shapes of snowflakes reflect the hexagonal crystal structure of ice. Accumulating layers of snow are basically layers of sediment. Continental glaciers = cast sheets of ice that spread over thousands of square kilometres of continental crust. How glaciers form: grow in or adjacent to mountainous regions are classified by their shape and position. Snow falls and packs together, and gradually transforms into a solid mass of ice composed of ice interlocking ice crystals. Snow compacts and melts to form firn , which recrystallizes into glacial ice in a process like metamorphism. Below 50-60km the properties change so the ice is plastic and can flow. Plastic deformation and flow downslope occurs as gravity pulls the built up snow and ice down kill (a frozen river )
