Earth Sciences 1022A/B Lecture Notes - Lecture 3: Esker, Kame, Continental Drift
Document Summary
Earth sciences 1022a lecture brief 17 nov 15. Glaciers: form by compaction, re-crystallization of snow that eventually turns into ice. Types include: ice sheets that are radial-spreading large ice masses on continents (e. g. antarctica); and valley in mountains, commonly flow down old stream valleys. If accumulation > ablation, the glacier"s terminus commonly advances; If accumulation < ablation, its terminus usually retreats. Internal movement within a glacier is always toward the front, even during retreat. Forms lateral moraines built along the sides of valley glaciers; end moraines (curved ridges) at the glacier terminus where it piles debris by dumping and bulldozing; and ground moraine is plastered beneath glaciers. Causes: plate tectonics and continental drift bring a major continent over a pole, allowing glaciation to start (by inducing global cooling) Glaciations are controlled by three cycles related to earth"s orbit around the sun.