Deck 14: Deserts and Wind

Question 1

When dunes are buried by younger sediment and lithified, __________ __________ form.

Answer 1

fossil dunes

Question 2

A dry desert lake bed is a __________.

Answer 2

playa

Question 3

__________ __________ __________ form on the leeward sides of a mountain range.

Answer 3

Rain-shadow deserts

Question 4

__________ commonly form along the front of desert mountains uphill from bajadas.

Question 5

Sand grains are transported by wind close to the ground in a bouncing movement called __________.

Question 6

The __________ is the semiarid zone south of the Sahara desert.

Question 7

Large __________ deposits accumulated in North America during the Pleistocene Ice Age from wind transporting and depositing big amounts of silt.

Question 8

A/an __________ is a broad, gently sloping depositional surface formed by merging alluvial fans.

Question 9

The growth of a desert by human mismanagement is called __________.

Question 10

The leeward face of a dune is called the __________ __________.

Question 11

Wind erosion, called __________, is a selective process in which the wind moves only small particles, such as silt and sand.

Question 12

Outside of the polar regions, the Earth's land surface is __________ desert.

A) 50 percent
B) less than 3 percent
C) about 25 percent
D) about 10 percent

Question 13

__________ dunes are common in moist semiarid regions and along the seacoast.

Question 14

Because Death Valley has no external drainage, the __________ eroded from surrounding mountains creates bajadas, pediments, and alluvial fans.

Question 15

A desert is defined as any region that receives less than __________ centimeters of rain per year.

A) 25
B) 28
C) 31
D) 35

Question 16

Many of the world's deserts lie at about __________ south and north latitude because here sinking air absorbs water, the ground surface is dry, and rainfall is infrequent.

A) 10°
B) 20°
C) 30°
D) 40°

Question 17

A/an __________ is a flat-topped mountain shaped like a table common to the Colorado Plateau.

Question 18

Any region that receives less than 25 centimeters of rain per year is considered to be a __________.

Question 19

A __________ is a desert lake bed that is dry most of the year.

A) playa
B) spring
C) bajada
D) wash

Question 20

A streambed that is dry most of the year is called a __________.

A) playa
B) spring
C) bajada
D) wash

Question 21

When a dry desert streambed suddenly fills with water during a rainstorm, this is called a/an __________ flood.

A) surprise
B) attack
C) race
D) flash

Question 22

In the Great Basin of the western United States:

A) buttes and mesas are common.
B) no streams flow into or away from the region.
C) little sediment accumulates because much of the region is desert or semiarid.
D) sediment is filling the valleys because streams flow into the valleys from surrounding mountains, but no streams flow away from the region.

Question 23

__________ is a continuous cover of stones left behind when wind blows silt and sand away.

A) A wash
B) A desert playa
C) A dune field
D) Desert pavement

Question 24

A dune that accumulates as long ridges that align perpendicularly to the prevailing wind is a __________ dune.

A) parabolic
B) transverse
C) barchan
D) longitudinal

Question 25

Desert pavement forms because:

A) playa lake beds bake rock-hard in the hot summer sun.
B) wind selectively removes sand and silt and leaves large particles behind.
C) caliche deposits cement desert soil.
D) clay is easily removed.

Question 26

Salt deposits are found on playas because:

A) of extreme erosion.
B) they are transported there by the wind.
C) salt diapirs are preferentially exposed in playa lakes.
D) dissolved ions precipitate during evaporation of the playa lake water.

Question 27

Large desert rivers, like the Nile River, receive most of their water from:

A) ground water reserves.
B) occasional, intense summer thunderstorms.
C) seasonal rains.
D) wetter, mountainous areas bordering the arid lands.

Question 28

Buttes and mesas are common in the Colorado Plateau because:

A) these landforms are composed of evaporite deposits.
B) these landforms commonly form at the base of bajadas.
C) chemical weathering rounds the edges of rock outcrops.
D) through-flowing rivers carve out these features.

Question 29

Erosion of soil by wind is __________.

A) deflation
B) saltation
C) inflation
D) desertification

Question 30

The largest loess deposits in the world are found in __________.

A) New York
B) the North American Great Plains
C) central China
D) the Atacama Desert in Peru

Question 31

Many of the world's deserts lie at 30° south and north latitude because:

A) falling air is compressed and becomes cooler, which enables it to hold more water vapor.
B) sinking air absorbs water, the ground surface is dry, and rainfall is infrequent.
C) rising air is heated and the moisture condenses.
D) rising air absorbs water, the ground surface is dry, and rainfall is infrequent.

Question 32

Water vapor that has condensed over a mountain range is more likely to fall as rain and snow:

A) near the equator.
B) in a rain-shadow desert.
C) on the windward side of the range.
D) on the leeward side of the range.

Question 33

Human mismanagement can cause the conversion of semiarid land to arid land in a process called __________.

A) dissertation
B) desiccation
C) desertification
D) dissolution
Multiple Choice

Question 34

Death Valley:

A) is a coastal desert.
B) has no water or plant life.
C) is a rain-shadow desert.
D) is drained by streams that flow through it to the ocean.

Question 35

A crescent-shaped dune with its tips pointing downwind that forms in rocky deserts with little sand is a __________ dune.

A) parabolic
B) transverse
C) barchan
D) longitudinal

Question 36

In the Atacama Desert of South America:

A) warm marine air encounters cool land, which absorbs moisture from the ground, creating a coastal desert.
B) cool marine air encounters warm land and heats up. The heated air then absorbs moisture from the ground, creating a coastal desert.
C) warm, moist air sinks, creating low pressure.
D) all of the moisture falls on the windward side of the range.

Question 37

Vast tropical forests grow near the equator because:

A) rising equatorial air cools and condenses as rain.
B) warm, moist air rises to form a high pressure region.
C) warm moist air sinks, creating low pressure.
D) rising air is heated and the moisture condenses.

Question 38

A __________ is a broad, gently sloping surface eroded into bedrock.

A) bajada
B) pediment
C) butte
D) ventifact

Question 39

Wind-scoured depressions are called __________.

A) alluvial fans
B) blowouts
C) kettles
D) playa lakes

Question 40

The leeward side of a dune is called the __________ face.

A) slip
B) shadow
C) saltation
D) ocean

Question 41

Most dunes are symmetrical.

Question 42

Desert streams usually receive their moisture from wetter, mountainous lands on their borders.

Question 43

Windblown sand is an effective agent of erosion.

Question 44

Deserts never occur along coastlines.

Question 45

Migrating dunes can overrun buildings and highways.

Question 46

Loess is:

A) silt that has been transported and deposited by wind.
B) a type of glacial moraine.
C) a dried-out river bed.
D) a fossil dune.

Question 47

The Atacama Desert along the west coast of South America is so dry that, on the average, portions of Peru and Chile receive no rainfall for a decade or more.

Question 48

Desertification in the Sahel in the late 1960s and early 1970s probably happened because of:

A) movement of the African continent.
B) tectonic uplift.
C) volcanic activity.
D) human mismanagement.
True/False

Question 49

A bajada is an erosional surface.

Question 50

The sand on the slip face of a dune is loose compared to the windward face.

Question 51

Because sand grains are relatively heavy, wind rarely lifts sand more than 1 meter above the ground and carries it only short distances.

Question 52

The day after a flash flood, a desert wash may contain only a tiny trickle, and within 24 hours, it may be completely dry again.

Question 53

Rainfall patterns and deserts have no direct relationship to tectonic activity.

Question 54

Many of the world's largest deserts lie at about 30° north and south of the equator.

Question 55

In fossil dunes:

A) numerous fossils form limestone.
B) numerous fossils have been obliterated by wind action.
C) the dipping beds are the layering of the dune's windward face.
D) the dipping beds are the layering of the dune's slip face.

Question 56

When a barchan dune migrates, the edges move more slowly because there is more sand to transport.

Question 57

When moisture-laden air flows over a mountain range, it cools and loses its ability to hold moisture.

Question 58

The effects of abrasion by windblown sand and silt:

A) form blowouts.
B) are responsible for the delicate caps on high desert pinnacles.
C) are concentrated close to the ground.
D) form playa lakes.

Question 59

Much of the rich loess of the central plains of the United States is the result of the Pleistocene Ice Age.

Question 60

Wind erodes sand:

A) from both sides of a dune.
B) from the leeward side of a dune, and deposits it on the windward side.
C) from the windward side of a dune, and deposits it on the sheltered leeward side.
D) only from the top of a dune.