GGR201H1 Lecture Notes - Lecture 5: Last Glacial Maximum, Aeolian Processes, Desert Pavement
11 Jan 2017
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Document Summary
Wind caused by pressure gradients in earth"s atmosphere and earth"s rotation. Air can only carry find sediments - aeolian sediments tend to be well sorted. Arid areas, beach coastlines, and some fluvial systems where dry sediments are exposed to winds after floods are shaped primarily by aeolian processes. Deflation - lowering of land surface by wind erosion (deflation basins) Aeolian bedform scale: micro-scale (seconds to years) - ripples and simple dunes (transverse, meso-scale (years to decades) - dunes of different types, macro-scale (decades to millennium) - complex multi-scale nested bedforms, mega-dunes, erg. Large dunes have morphologies adjusted to past climates and wind patterns - will take existing wind and climate long time to fully transform. Desert pavement -- forms as wind entrains all the fine sediment leaving behind only the coarse sediment. Shear velocity: the rate of change of velocity with height. Barchan dune: wind flow in one direction, less sediment. Transverse: wind flow in one direction, more sediment.
