Earth Sciences 1022A/B Lecture 18: Earth Science Lecture March 17 2016

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

Document Summary

Deserts are dry places where there is low precipitation and little vegetation. In spite of lack of water and vegetation processes still occur. Weathering: almost entirely mechanical and very slow due to low precipitation. However, clays and thin soils form by oxidation of ferromagnesian silicate minerals. Water: ephemeral streams and flash floods from short, intense rainstorms do most of the erosion of desert surfaces, especially sediment not anchored by vegetation. Wind can move faster than water and carries sediment farther and higher than streams because flow is not confined to channels. Bedload: sand moves by saltation and by rolling over the ground. Suspended load: dust particles are pushed into the air by saltating sand grains. The grains are then swept up by the wind in dense clouds and carried high into the air. Occurs by deflation and abrasion: deflation. Blowing away fine sediment to create blowouts while leaving coarser particles behind that cover the desert floor as desert pavements: abrasion.