Deck 16: Deserts and Wind

Question 1

Which one of the following statements is CORRECT?

A)Saline sediments and evaporites are common in inselbergs and pediments of desert landscapes.
B)Playas are typically covered with gravel- sized desert pavement and loess deposits.
C)Inselbergs are low, circular depressions on gently sloping pediments and bajadas.
D)Alluvial fans typically rim desert valleys; playas form in the lowest, interior parts of the valleys.

Answer 1

D

Question 2

dunes are long, high, sand dunes parallel with the prevailing wind direction.

A)Longitudinal
B)Latitudinal
C)Transducinal
D)Transversal

Answer 2

A

Question 3

How is desert pavement formed?

A)Deflation removes the coarse fragments leaving behind a layer of loess.
B)Runoff and deflation carry off the silt and clay, leaving coarser particles behind.
C)Alluvial fans are eroded to form inselbergs with rocky surfaces.
D)Groundwater in an alluvial fan evaporates, leaving behind a surface layer of hard- baked mud.

Answer 3

B

Question 4

Which one of the following statements is TRUE?

A)Rainshadow deserts occur on the windward side of a mountain when air masses are forced to rise upwards.
B)Deserts and dry lands are concentrated in areas of ascending air masses and relatively low atmospheric pressures.
C)Despite infrequent rainfalls, erosional and depositional features of running water are important in desert landscapes.
D)Desert landscapes are monotonous, relatively flat areas covered to various depths with sand.

Question 5

What mature, desert landscape feature consists of coalesced alluvial fans?

A)bahia
B)balda
C)bajada
D)baja

Question 6

refers to the "bouncing" mode of sand transport in a windstorm or stream.

A)Deflation
B)Saltation
C)Ventifaction
D)Siltation

Question 7

Assume that the central slip face of a barchan dune slopes downhill toward the east. What is the direction of the prevailing wind?

A)west to east
B)north to south
C)south to north
D)east to west

Question 8

Which one of the following is a low- latitude desert characterized by high atmospheric pressures and descending air masses (not rain shadow deserts)?

A)Gobi Desert, China and Mongolia
B)desert valleys of the Great Basin, United States
C)Sahara Desert; northern Africa
D)Atacama Desert in Chile, South America

Question 9

Which of the following best describes the climatic factors that cause low latitude deserts like the Sahara in Africa?

A)Cool, dry air aloft is descending; surface winds are blowing toward the equator.
B)Cool, dry air at the surface is rising causing winds to blow away from the equator.
C)Warm, humid air is rising; surface winds are calm.
D)Warm, humid air aloft is descending; surface winds blow away from the equator.

Question 10

Which one of the following is the one best measure of the wetness or dryness of a region?

A)difference between annual precipitation and evaporation potential
B)total annual precipitation
C)mean annual temperature
D)percentage of precipitation that falls during the summer months

Question 11

Which of the following characteristics would suggest recent, fault uplift of a desert mountain range?

A)steep playas with extensive, bedrock alluvial fans and numerous sand dunes
B)extensive pediments and bajadas and small, deep playas
C)flat, upland surfaces, steep slopes and small alluvial fans
D)inselbergs, extensive pediments and flat valley floors

Question 12

Rainshadow deserts are common in _ _.

A)vast, dry, steppe lands like the Great Plains
B)the dry valleys of eastern California and Nevada
C)north central Africa
D)Europe north of the Alps

Question 13

Loess deposits in the central United States .

A)were originally deposited as barchanoid dunes and later redeposited by glaciers
B)originated as rock flour in Pleistocene glacial streams and rivers
C)accumulated from flooding of the Mississippi River
D)blew in from the dry areas in the Great Plains and southwestern desert areas

Question 14

All of the following statements concerning dry lands are true EXCEPT .

A)evaporation potential exceeds actual precipitation
B)storms are infrequent and rainfall amounts are highly variable
C)wind is the dominant agent of erosion and sediment transport
D)precipitation totals are low; dew points are lower in the summer than winter

Question 15

Desertification has been particularly well documented over the past 50 years in .

A)the Empty Quarter of the Arabian Peninsula
B)the Dust Bowl states of the Great Plains
C)the steppe lands of southern Russia, Ukraine, and Kazakhstan
D)the Sahel along the southern margin of the Sahara Desert

Question 16

Inselbergs are .

A)bedrock hills in a highly eroded desert landscape
B)blowouts cut from bedrock in mountainous areas
C)insulated icebergs floating in a hot spring
D)lithified rock formed by cementation of wind- deposited, dune sands

Question 17

How are sand grains transported by the wind?

A)by being picked up in swirling dust clouds and carried to distant blowouts
B)high in the moving air column as suspended load
C)by saltation in the first few meters above the land surface
D)by deflation of abraded desert pavement

Question 18

A _ is a crescent- shaped dune whose tips point downwind.

A)transverse
B)parabarcal
C)barchan
D)star

Question 19

A _ is formed by abrasion of rocks by windblown sand.

A)desert pavement
B)ventifact
C)pediment
D)playa

Question 20

Which one of the following will effectively limit further deflation in a given area?

A)a hanging valley
B)the repose level
C)desert pavement
D)sea level

Question 21

Deposits of windblown silt are called .

Question 22

dunes form in areas where the prevailing wind directions change with the seasons.

Question 23

Wind is included along with gravity, water, and ice as an agent of erosion. In many national parks and other areas of natural beauty, statements are often made that credit wind as having sculpted the landscape. Briefly discuss the importance of wind as an agent of erosion and explain why such statements are probably geologically inaccurate.

Question 24

are solitary, crescent- shaped dunes whose tips face downwind.

Question 25

describes the complex, internal stratification or bedding in a sand dune.

Question 26

Which one of the following is determined by the angle of repose for dry sand?

A)slope of an alluvial fan
B)inclination angle of a dune slip face
C)a vertical cut bank in loess
D)longitudinal dune gradient angle

Question 27

are rocks with one or more flat surfaces abraded by windblown sand.

Question 28

Deposition of glacial rock flour from blowing winds is responsible for .

A)deflation ventifacts
B)loess deposits
C)star steppes
D)blowout pavement

Question 29

dunes are long, sand ridges that develop at right angles to the prevailing wind direction.

Question 30

Which one of the following statements about sand dunes is correct?

A)A dune migrates in the direction of inclination of the slip face.
B)In a sand dune, the more gently inclined strata lie parallel to the slip face.
C)The more gently sloping surface is the leeward slope of the dune.
D)Sand is blown up the slip face and rolls down the more gently sloping flank of the dune.

Question 31

Which one of the following would probably not affect the size and depth of a blowout?

A)the near surface water table
B)a rise in sea level
C)type and density of vegetation
D)areas of desert pavement

Question 32

Desert and steppe lands cover about what percentage of Earth's land area?

A)3%
B)30%
C)10%
D)66%

Question 33

Which one of the following concerning desert lands is FALSE?

A)Wind erosion and deposition are important processes.
B)Most desert areas are characterized by descending wind patterns.
C)Less than 30 percent is covered with dunes and drifting sand.
D)Running water has little effect on shaping the landscape.

Question 34

Most dry lands lie between degrees north and south of the equator.

A)0 and 5
B)40 and 50
C)5 and 10
D)20 and 30

Question 35

is the skipping and bouncing transport of sand in blowing wind and running water.

Question 36

dunes result from persistent, onshore winds in certain coastal areas.

A)Diabolic
B)Barchanoid
C)Staroid
D)Parabolic

Question 37

The low, bedrock ridges and peaks of a highly eroded, basin and range, desert landscape are called .

Question 38

In dry lands, is the covering of coarse particles left on the surface after the finer particles are carried away by wind and running water.

Question 39

A(n)is an intermittent lake on the floor of a desert basin.

Question 40

The leeward slope of a sand dune is also known as the _ _.