Deck 18: Deserts and the Work of Winds

Question 1

What is the term for a thin coating of oxide staining exposed rock surfaces in deserts?

A) Arroyo.
B) Desert varnish.
C) Desert pavement.
D) Ventifact.

Answer 1

B

Question 2

The bed- load of wind- transported sediment is moved by:

A) the process of surface creep.
B) the process of suspension.
C) the process of traction.
D) the process of saltation.

Answer 2

D

Question 3

Dust sediment in the wind's suspended load:

A) can travel in the upper atmosphere for a distance of thousands of kilometers.
B) travels at about twice the height and distance of the bed load.
C) travels in a narrow layer of dead space along the surface of the ground.
D) travels at about the same height and distance as the bed load.

Answer 3

A

Question 4

Polar deserts are considered deserts because:

A) they lack vegetation.
B) they receive little solar radiation.
C) they lack appreciable precipitation.
D) the temperatures remain below freezing year- round.

Question 5

Deserts that result from their location on the leeward side of mountain ranges are:

A) continental interior deserts.
B) deserts near cold ocean currents.
C) rain shadow deserts.
D) subtropical deserts.

Question 6

The primary sculptor of desert landforms is:

A) ice.
B) water.
C) wind.
D) gravity.

Question 7

Which of the following statements concerning dune migration is NOT true?

A) Small dunes migrate at about the same rate as larger dunes.
B) Large dunes migrate on the order of a few meters per year.
C) Coastal dunes may migrate seaward rather than inland.
D) Dunes migrate when sand saltates up the windward side and is deposited on the leeward side.

Question 8

In the hottest places on Earth, the temperatures can reach as high as:

Question 9

A desert is an area in which:

A) potential precipitation is four times greater than evaporation.
B) potential evaporation is four times greater than precipitation.
C) the total precipitation is less than 25 millimeters per year.
D) evaporation is greater than precipitation.

Question 10

Mechanical weathering processes in deserts include which one of the following?

A) Salt crystal growth in rock fractures.
B) Saltation.
C) Deflation.
D) All of the above.

Question 11

The prevailing orientation of a paleowind can be determined by loess because loess deposits:

A) thin in the downwind direction.
B) are inclined in the downwind direction.
C) are inclined in the upwind direction.
D) thin in the upwind direction.

Question 12

Which of the following statements correctly describes sand grains after they become airborne?

A) Grains overcome by gravity may nudge forward other grains they strike.
B) Grains overcome by gravity strike other grains, setting them in motion.
C) Particles move forward in curved, parabolic paths.
D) All of the above.

Question 13

Arroyos are:

A) desert stream channels that are usually dry.
B) accumulations of sediments at the ends of desert streams.
C) erosional remnants of mountains adjacent to deserts.
D) intense desert rainstorms.

Question 14

Which of the following statements about deserts is true?

A) Every continent on Earth contains at least one extensive dry region.
B) Deserts account for less than 10% of the Earth's land surface.
C) Desert climates are always hot and dry.
D) Desert landscapes consist mostly of sand.

Question 15

Areas near cold ocean currents are often deserts because of all of the following factors EXCEPT:

A) onshore winds that intensify evaporation.
B) dry offshore winds that block moist air.
C) subtropical warmth.
D) cool air above the ocean current.

Question 16

Transverse dunes are:

A) crescent- shaped dunes with horns in the upwind direction.
B) parallel ridges oriented perpendicular to the prevailing wind direction.
C) parallel ridges oriented parallel to the prevailing wind direction.
D) complex dunes that form when wind blows from three or more principal directions.

Question 17

What is the name for a global wind pattern blowing east to west at low latitudes?

A) Trade winds.
B) Northeasterly winds.
C) Southeasterly winds.
D) Westerlies.

Question 18

Which of the following statements concerning Martian winds is NOT true?

A) Storms usually start in the northern hemisphere.
B) Because of Mars' lower gravity, dust particles are carried four times as high as those carried by comparable winds on Earth.
C) They are caused by temperature differences that produce different air pressures.
D) They are caused by seasonal melting of the ice cap.

Question 19

What is the process involving the removal of loose Earth materials by wind?

A) Abrasion.
B) Infiltration.
C) Evaporation.
D) Deflation.

Question 20

Warm deserts that result from atmospheric convection cells are:

A) rain shadow deserts.
B) deserts near cold ocean currents.
C) subtropical deserts.
D) continental interior deserts.

Question 21

Continental interior deserts are a result of:

A) the rain- shadow effect of high mountain ranges.
B) the assembly of continental plates landlocks the region.
C) great distance from moisture- laden winds.
D) All of the above.

Question 22

Wind erodes solid rock by what process?

A) Abrasion.
B) Evaporation.
C) Deflation.
D) Infiltration.

Question 23

What is the term for wind- shaped stones found in deserts?

A) Inselberg.
B) Desert pavement.
C) Ventifact.
D) Desert varnish.

Question 24

Which of the following statements about desert streams is NOT true?

A) Desert streams erode soil easily because there is little vegetation to stabilize it.
B) Because the soil is compacted and sun- baked, most erosion within an arroyo is lateral rather than vertical.
C) Flash floods occur because water is not readily absorbed by desert soils.
D) Alluvial fans occur at the end of arroyos because desert stream water finally infiltrates or evaporates rather than flowing to the sea.

Question 25

Which of the following statements concerning wind transport is NOT true?

A) Wind does not need as high a velocity as a stream to transport particles.
B) Vegetation and coarse sediment create a layer of dead air on the ground.
C) The driving force of the wind and a particle's inertia are opposing forces in particle movement.
D) Wind does not lift a loose particle directly from the surface.

Question 26

Efforts to reverse desertification include all of the following EXCEPT:

A) controlling wind erosion.
B) pumping groundwater.
C) desalinating river water.
D) inhibiting evaporation.

Question 27

Which of the following statements about the bed load of a windstream is NOT true?

A) The air immediately above the bed load of a desert sandstorm is usually clear.
B) Desert sandstorms consist of bed load material generally carried at a height of 1 to 2 meters.
C) A bed load moves only by saltation; none of it is carried in suspension.
D) Bed load achieves a greater height when moving above soft, loose sand than above a hard, compacted surface.

Question 28

What is the term for streamlined desert ridges produced by wind erosion?

A) Inselberg.
B) Ventifact.
C) Pediment.
D) Yardang.

Question 29

The symptoms of desertification include all of the following EXCEPT:

A) decreased salinity in natural waters and soils.
B) progressive destruction of native vegetation.
C) significant lowering of the water table.
D) accelerated rate of erosion.

Question 30

All of the following are types of deserts EXCEPT:

A) cold.
B) hot.
C) temperate.
D) tropical.

Question 31

An aridity index of 2.0 indicates:

A) potential annual evaporation is one- half the average annual precipitation.
B) potential annual evaporation is twice the average annual precipitation.
C) the average annual evaporation is 2 inches.
D) the average annual precipitation is 2 inches.

Question 32

In which of the following locations would a dune be most likely to form?

A) Where a barren flat area provides a stable surface for sand accumulation.
B) Where a wind shadow has developed due to a change in wind direction.
C) Where a bush interrupts the flow of saltating sand.
D) Where a blowout alters the flow of the wind.

Question 33

All of the following factors contributed to the Dust Bowl condition EXCEPT:

A) overcultivation of wheat crops.
B) widespread flooding in the region.
C) increase in frequency of high- velocity winds.
D) plowing of the prairie sod.

Question 34

What is the term for a dry lakebed located on the desert floor?

A) Arroyo.
B) Oasis.
C) Playa.
D) Pediment.

Question 35

Sand dunes are produced by which one of the following mechanisms?

A) Dissolved- load deposition.
B) Wash- load deposition.
C) Bed- load deposition.
D) Suspended- load deposition.

Question 36

What is the term for an erosion surface with a slope of 5° or less at the base of a mountain?

A) Inselberg.
B) Ventifact.
C) Pediment.
D) Yardang.

Question 37

The characteristic of loess that makes it an exceptional soil is:

A) its angular grains.
B) its fresh, unweathered mineral content.
C) its high moisture- holding capacity.
D) All of the above.

Question 38

All of the following statements are clues to past, more severe droughts that occurred in the Great Plains of North America EXCEPT:

A) salt- dependant diatoms are found in lake- sediment cores.
B) tree rings record evidence of past dry spells.
C) evidence of forest expansion from river valleys.
D) there is evidence of periods when sand dunes were expanding.

Question 39

The driest region on the Earth is:

A) Antarctica.
B) the Sahara.
C) the Gobi desert.
D) Death Valley.

Question 40

Which of the following statements concerning alluvial fans is NOT true?

A) Water that seeps into the surface may reemerge as a spring at the base of a fan.
B) Alluvial fans form because streams usually travel for long distances in deserts.
C) The size of an alluvial fan is proportional to the size of its drainage basin.
D) Alluvial fans may contain enough water to irrigate the adjacent desert area for cultivation.

Question 41

Why is it dangerous to be caught in an arroyo during desert thunderstorms?

Question 42

Describe the process of saltation.

Question 43

Identify and discuss the characteristic that defines a desert.

Question 44

Discuss the action of wind on Mars, and describe the Martian wind's depositional features.

Question 45

What evidence indicates the occurrence of earlier droughts in the Great Plains more severe than the Dust Bowl?

Question 46

Discuss how sand dunes are formed.

Question 47

List four methods used in attempting to reverse desertification.

Question 48

How do pediments and inselbergs form?

Question 49

List the factors that determine the height of a wind- transported bed load.

Question 50

Discuss the formation of blowouts and deflation basins.