!GLG 101-Illustrated Vocabulary-Chapter 13
!Winds and Deserts
copyright 2003-Roger Weller
!aeolian
*refers to a wind-blown environment which might include sand dunes or desert
pavement. Alternative spelling is eolian.
!alluvial fan
*a deposit of sediment deposited at the base of a mountain where a stream coming off the
mountain dumps its load. The sediments usually form a fan-like cone shape that gives
this structure its name.
*[Southern Nevada-Alluvial Fan-1]
*[Southern Nevada-Alluvial Fan-2]
*[Yosemite-Alluvial Fans]
!Badlands Topography
*an area almost without any plants that has eroded into a complex array of jagged
pinnacles and many narrow ravines.
*[Bryce Canyon-1]
!bajada
*overlapping alluvial fans.
*[Southern Nevada-Alluvial Fan-1]
!barchan
*a sand dune with a crescent shape.
!butte
*a hill or small mountain, usually with steep sides, that stands apart from surrounding
hills or mountains.
*[Arizona-Sedona-1]
*[Arizona-Sedona-8]
!caliche
*soil cemented by lime (calcite); very common in the Southwest U.S.A. Resembles
concrete.
!coalesced alluvial fans
*several alluvial fans at the base of a mountain overlap each other.
*[Southern Nevada-Alluvial Fan-1]
!cross bedding
*a primary sedimentary structure in which one set of inclined sedimentary layers is
beveled off by an erosional process and a new set of sedimentary layers is deposited on
top of the truncated original layers; common in stream sediments and sand dunes.
*[Crossbedding-Roadcut-2]
*[Crossbedding-Roadcut-4]
!desertification
*the process by which a fertile area slowly becomes a desert.
!desert pavement
*the desert surface is completely covered with a layer of wind polished interlocked
pebbles, resembling a paved surface.
!desert varnish
*rocks in a hot desert area, such as around the Phoenix, Arizona area, acquire a dark
coating made of iron and manganese oxides along with polymerized organic compounds.
!Dust Bowl
*dry, windy conditions during the 1930s subjected the Great Plains of the United States
to great dust storms that stripped away soil.
!eolian
*an ajective indicating a windblown, desert environment; also spelled aeolian.
!exfoliation
*a weathering process, common in semiarid regions, in which the weathered outer
portion of a granite boulder peels off in slabs parallel to the surface of the boulder; often
compared to the peeling away of layers of an onion.
*[Chiricahuas-Exfoliation]
*[Mt.Whitney-Alabama Hills-Exfoliation-Close Up]
!flash flood
*a dry wash (stream channel) that suddenly fills with water. The water level in the
channel quickly rises, surge after surge. Often the source of the water may be a rainstorm
in the mountains many miles away.
!lee slope
*the steep side of a sand dune that faces away from the wind
!loess
*a loose, silty soil, perhaps derived from rock flour (rocks ground up by glaciers) that has
been deposited by the wind.
!mesa
*a flat-topped mountain or plateau bounded at least on one side by a cliff; the term a
comes from Spanish and means table.
!pedocal
*a soil found in semiarid regions, rich in calcite.
!playa
*a dry lake bed
!salinization of soils
*the buildup of salt in the soil thereby decreasing the useful of the soil for agriculture; a
growing problem in the western part of the United States.
!saltation
*a form of transportion of materials by rolling, bouncing, and skipping. The term is often
applied to wind-blown sand grains moving over the surface of sand dunes.
!salt buildup
*if there is insufficient drainage of agricultural watering of crops, then salt,which is
produced by the breakdown of soil minerals, is not washed out of the system.
Consequently, the concentration of salt slowly builds up until plants cannot live in the
soil.
!sandblasting
*a form of physical weathering in which wind slams hard sand grains into softer
substances
!sand dune
*a large pile of sand shaped by wind action.
!sandstorm
*a violent storm, very windy, that picks up sand grains and causes sandblasting
!thermal expansion
*occurs when most materials are heated. Similarly, most materials contract in size when
cooled. Repeated heat-cold cyles loosen grains within rocks and may cause the rock to
eventually crumble.
!ventifact
*a rock shaped by sandblasting
!White Sands, New Mexico
*a national park near Alamagordo, New Mexico noted for large white sand dunes made
of gypsum