Exam 4 Flashcards
(131 cards)
Which of the following is the 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
What mature desert landscape feature consists of coalesced alluvial fans?
Bajada
What are inselbergs?
Bedrock hills in a highly eroded desert landscape
What term refers to the “bouncing” mode of sand transport in a windstorm or stream?
Saltation
Where did the great loess deposits in the central United States originate?
They originated as rock flour in Pleistocene glacial streams and rivers.
Which one of the following is determined by the angle of repose for dry sand?
Inclination angle of a dune slip face
Which one of the following concerning desert lands is FALSE?
Wind is the dominant agent of erosion and sediment transport.
Running water has little effect on shaping the landscape
Running water has little effect on shaping the landscape.
Which one of the following statements concerning rock weathering is true?
Warm temperatures and high soil moisture accelerate chemical weathering.
Which of the following statements concerning dry lands is FALSE?
Wind is the dominant agent of erosion and sediment transport.
Running water has little effect on shaping the landscape
Wind is the dominant agent of erosion and sediment transport.
Which dune is crescent-shaped with its tips pointing downwind?
Barchan
Where are rain shadow deserts common?
The dry valleys of eastern California and Nevada
What type of deposit consists of glacial rock flour from blowing winds?
Loess
What percentage of Earth’s land area do desert and steppe lands cover?
3o%
Where has the process of desertification been particularly well documented over the past 5o years?
The Sahel along the southern margin of the Sahara Desert
Between which latitudes do most dry lands lie?
Between 20 and 3o degrees north and south of the equator
Which of the following is formed from the abrasion of rocks by windblown sand?
Ventifacts
Which sand dunes are long, high, and parallel with the prevailing wind direction?
Longitudinal
Which of the following statements about deserts is true?
Deserts are lifeless.
Wind is the most significant agent of erosion in desert regions.
Deserts are always hot.
Water is the most significant agent of erosion in deserts.
Deserts are dominated by sand dunes.
Water is the most significant agent of erosion in deserts.
Which of the following statements characterizes ephemeral streams?
Ephemeral streams flow only at certain times of the year.
Ephemeral streams don’t have any life in them.
Ephemeral streams flow all the time in the desert.
Ephemeral streams generally depend on groundwater in the desert to flow year round.
Ephemeral streams are streams that flow through deserts, but hay their origins outside of the desert
Ephemeral streams flow only at certain times of the year.
Which one of the following is an evaporite mineral?
clay quartz calcium gypsum
gypsum
What is a playa commonly occupied by?
an ephemeral lake a sand dune Salt-tolerant vegetation a dome an interdune
an ephemeral lake
What does saltating mean?
Flakes of gypsum mineralize to form crystals that resemble the shape and size of salt grains.
Sand grains avalanche down the slip face of a dune.
Sand grains are lifted by the wind, leap a short distance, and then fall back to the ground.
Sand grains pile up to form little ripples that grow into larger dunes.
Clay particles rotate through the air as they are blown by desert winds.
Sand grains are lifted by the wind, leap a short distance, and then fall back to the ground.
What is the angle of repose for sand on the slip face (leeward side)?
90 degrees
10 degrees
40 degrees
34 degrees
34 degrees