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20 terms

ESCI 111 Quiz 19

STUDY
PLAY
________ have rainfall amounts and soil moisture contents between those of true deserts and humid lands.
Steppes
Most dry lands lie between ________ degrees north and south of the equator.
20 and 30
A ________ is an intermittent stream channel in the dry land areas of the western United States.
wash
________ refers to the "bouncing" mode of sand transport in a windstorm or stream.
Saltation
Which one of the following will effectively limit further deflation in a given area?
desert pavement
Which one of the following statements is correct?
Alluvial fans typically rim desert valleys; playas form in the lowest, interior parts of the valleys.
Which of the following characteristics would suggest geologically recent, fault uplift of a desert mountain range?
flat, upland surfaces, steep slopes and small alluvial fans
How is desert pavement formed?
Runoff and deflation carry off the silt and clay, leaving coarser particles behind.
Deposition of glacial rock flour from blowing winds is responsible for ________.
loess deposits
Which one of the following is the one best measure of the wetness or dryness of a region?
difference between annual precipitation and evaporation potential
How are sand grains transported by the wind?
by saltation in the first few meters above the land surface
Which of the following best describes the climatic factors that cause low latitude deserts like the Sahara in Africa?
Cool, dry air aloft is descending; surface winds are blowing toward the equator.
Loess deposits in the central United States ________.
originated as rock flour in Pleistocene glacial streams and rivers
Assume that the central slip face of a barchan dune slopes downhill toward the east. What is the direction of the prevailing wind?
west to east
Desert and steppe lands cover about what percentage of Earth's land area?
30%
Inselbergs are ________.
bedrock hills in a highly eroded desert landscape
A ________ is formed by abrasion of rocks by windblown sand.
ventifact
A ________ is a crescent-shaped dune whose tips point downwind.
barchan
During a typical sandstorm, saltating sand grains reach a maximum height of ________ above the land surface.
2 meters
Rainshadow deserts are common in ________.
the dry valleys of eastern California and Nevada