Earth Sciences 1022A/B Lecture 17: Earth Science Lecture March 15 2016

• School: Western University
• Department: Earth Sciences
• Course: Earth Sciences 1022A/B
• Professor: Stephen R Hicock

Document Summary

Formed by compaction and re-crystallization of snow that eventually turns into ice. Radial spreading large ice masses on continents. It is an upper brittle zone of fracture that rides on a lower zone of plastic flow: ~50m thick, may also slide over its bed. Budget of a glacier: involves two zones. Wastage or loss by melting, evaporation and icebergs calving in water: if accumulation is greater than ablation the glacier"s terminus commonly advances, if accumulation is less than ablation its terminus usually retreats. Internal movement within a glacier is always towards the front even during retreat. Lecture: freeze-on of loose bedrock, using the glacier"s load to scrape, scour and gouge the subglacial floor and sides. Striation and grooves form by particles in ice scraping over bedrock. Glaciated valleys become fjords along coasts: u-shaped. Aretes and horns form where multiple cirque glaciers gnaw into a mountain divide from the sides: sharp ridges and pyramid shaped peaks.