Geology 101 : Winds and Desert
Geology 101 : Winds and Desert 101-017
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This 3 page Class Notes was uploaded by Natalee Stanton on Friday April 15, 2016. The Class Notes belongs to 101-017 at University of South Carolina taught by in Winter 2016. Since its upload, it has received 9 views. For similar materials see Geology 101-017 in Geology at University of South Carolina.
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Date Created: 04/15/16
GEOL 101 Winds and Deserts Deserts – regions that receive less than an inch of precipitation o Doesn’t have to do with temperature Found on every major continent Found on 1/5 of earth land surface o More than any other geographical environment Polar regions are another form of desert because of little precipitation because cold air doesn’t hold a lot of moisture A dominance of physical weathering Desert varnish – a weathering veneer formed of a mixture of clay and iron and manganese oxides Desertification – invasion of desert conditions into formerly non desert areas o Contributing factors Drought Overpopulation Land mismanagement I. Factors in atmosphere circulation Warm air o Rises o Holds more water Cold air o Sinks o Holds less water Land surface change temperature much more rapidly than water surface Earth is rotating causing a twist in the air circulation II. Wind (Eolian) – natural flow of air that is typically parallel to the surface of the earth o Little surface Wind at the equator, and the air rises, forming clouds and it rains as it cools. How wind blows o Tropics – winds blow from the east These regions have the most desert o Temperate latitudes– winds come from the west o Coriolis – responsible for the direction of the wind The amount of material the wind can carry o Wind strength o Particle size o Surface material The rate of sand transported by wind increases exponentially with wind speed Loess a blanket of sediment composed of fine grained particles it is deposited by wind o Usually it lacks layers III. Dust o Includes some larger silt particles o Includes microscopic rock and mineral fragments of all kinds, especially silicate o Strong winds can’t move larger pebbles o Wind cant erode and transport wet soil The amount of dust in the atmosphere increases with o Agriculture o Deforestation o Erosion Deflation – the process that describes the gradual erosion of the around surface by wind o Occurs In dry areas where the vegetation is not abundant Desert pavement o A surface of gravel too large for the wind to transported IV. Dunes – given enough sand and wind, any obstacle such as large rock or a clump of vegetation can start a dune o If the wind is too strong, the dunes will stop forming Sand dunes Form parallel to the wind o Requires loose sand, strong winds, and dry climate Downwind migration of dunes o Erosion on the upwind side of dunes and deposition of the sand on the dune Sample Exam Questions Which of the following terms describes a curved, coarsegrained sedimentary deposit that forms on the inside bend of a stream? a. Dune b. Point bar c. Oxbow d. Meander Which of the following processes doesn’t increase the amount of dust in the atmosphere? a. Agriculture b. Deforestation c. Precipitation d. Erosion For which direction do the trade winds in the tropics blow? A. East B. North C. South D. west