Presentation on theme: "Aeolian processes. pertain to the activity of the winds and more specifically, to the winds' ability to shape the surface of the Earth and other planets."— Presentation transcript:
deflation zones Regions which experience intense and sustained erosion. Composed of desert pavement, a sheet- like surface of rock fragments that remains after wind and water have removed the fine particles
Rock carved by drifting sand below Fortification Rock in Arizona (Photo by Timothy H. O'Sullivan, USGS, 1871) A rock sculpted by wind erosion in the Altiplano region of Bolivia Sand blowing off a crest in the Kelso Dunes of the Mojave Desert, California
Surface creep accounts for as much as 25 percent of grain movement in a desert.
A massive sand storm cloud is close to enveloping a military camp as it rolls over Al Asad, Iraq, just before nightfall on April 27, 2005. Dust storm approaching Spearman, Texas April 14, 1935. Dust storm in Amarillo, Texas. FSA photo by Arthur Rothstein (1936)
Deposition Wind-deposited materials hold clues to past as well as to present wind directions and intensities. These features help us understand the present climate and the forces that molded it. Wind-deposited sand bodies occur as sand sheets, ripples, and dunes.
SAND SHEETS Sand sheets are flat, gently undulating sandy plots of sand surfaced by grains that may be too large for saltation. They form approximately 40 percent of aeolian depositional surfaces.
Ripples In ripples, the coarsest materials collect at the crests causing inverse grading. This distinguishes small ripples from dunes, where the coarsest materials are generally in the troughs.
Crossbedding of sandstone near Mt. Carmel road, Zion Canyon, indicating wind action and sand dune formation prior to formation of rock (NPS photo by George A. Grant, 1929) Mesquite Flat Dunes in Death Valley looking toward the Cottonwood Mountains from the north west arm of Star Dune (2003) Holocene eolianite deposit on Long Island, The Bahamas. This unit is formed of wind-blown carbonate grains. (2007)