GEO 101 Lecture Notes - Lecture 18: Deflation, Desert Pavement, Abrasive Blasting
2 May 2017
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Document Summary
Defined by lack of rainfall, not high temperature. Typically, less than 25 cm of rainfall per year. Vegetation on less than 15% of surface. Forcing the air up to a higher elevation. The exact cause of desert varnish is poorly understood, but may involve microorganisms leaching out iron and magnesium from dust that coats moist rock to form fe and mg oxides. Petroglyph- drawings formed by chipping into the desert varnish of rocks to reveal the lighter rock beneath: flash flood- a flood that occurs during unusually intense rainfall, during which the floodwaters rise very fast. Process can occur within just a few decades. Caused by natural droughts, over population, over grazing, careless agricultural practices, and diversion of water supplies: dust bowls. The 1933 dust bowl was caused by over population in the mid-west, poor agricultural practices (too much plowing), and drought. Many people lost their farms and were displaced.
