The Lowering Of The Desert Floor As Wind Eroded Sediments

Wind can carry small particles such as sand silt and clay.

The lowering of the desert floor as wind eroded sediments.

In arid regions small particles are selectively picked up and transported. A fan shaped deposit of sediment formed when a stream s slope is abruptly reduced alluvial fan a flat area on the floor of an undrained desert basin playa that fills and becomes heavy rain. Once these eroded materials are settled and piled up in a new location it is referred to as deposition. Deflation concentrates the coarser grained particles at the surface eventually resulting in a surface composed only of the coarser grained fragments that cannot be transported by the wind.

Winds in the desert are often extreme and unrestricted by trees and vegetation. When the wind blows across loose sediment it removes small particles like clay silt and sand leaving the courser heavier sediment behind. Wind can be an effective erosion and transportation agent if it is strong and blows across fine grained sediment such as sand silt and clay. Loess is a very fine grained wind borne deposit that can be important to soil formation.

A wind s bed load consists of the heavier grains usually sand that hop and skip along the ground by saltation. Wind erosion abrades surfaces and makes desert pavement ventifacts and desert varnish. Sand dunes are common wind deposits that come in different shapes depending on winds and sand availability. Typically made out of sedimentary rocks usually sandstone laid down in horizontal layers this layering generally makes the zeugen flat topped and stepped in profile because most abrasion is concentrated within a metre or so of the desert floor zeugen often have a slightly narrower more eroded lower portion.

Water is also able to erode land by the effects of currents and ocean waves. A marvel of nature the lakes of ounianga in the sahara desert have lasted thousands of years and withstood dramatic climate change. Now a german geologist has analyzed lakebed sediments to shed. Deflation is the lowering of the land surface due to removal of fine grained particles by the wind.

As they are removed the ground surface gets lower and rockier causing deflation. As a grain strikes another grain or surface it erodes that surface. What is left is desert pavement a surface covered by gravel sized particles that are not easily moved by wind particles moved by wind do the work of abrasion. Once the eroded particles as a result of ocean currents and waves are settled and deposited they enormously change the coastline of the area.