Deck 17: Dry Regions: The Geology of Deserts

Question 1

________ deserts form on the leeward (dry)side of mountain ranges.

A)Tropical
B)Rain-shadow
C)Coastal
D)Subtropical

Answer 1

B

Question 2

The figure below illustrates the formation of a ________ desert.

A)coastal
B)subtropical
C)rain-shadow
D)continental-interior

Answer 2

A

Question 3

Physical weathering is more prevalent in the desert due to the ________.

A)high amounts of heat that bake the rocks
B)absence of ice,which can seal fractures
C)lack of water for chemical reactions
D)low levels of iron that produce oxidation

Answer 3

C

Question 4

Deserts represent ________ of Earth's surface.

A)less than 5%
B)about 10%
C)about 25%
D)more than 50%

Question 5

________ deserts occur due to the drying out of air masses over the equatorial rain forests.

A)Subtropical
B)Rain-shadow
C)Polar
D)Continental-interior

Question 6

The majority of erosion in the desert is due to ________.

A)wind
B)water
C)ice
D)heat

Question 7

________ forms when dust carrying microbes sticks to the outside of a rock and forms an iron oxide-rich covering.

A)Desert varnish
B)Desert pavement
C)A ventifact
D)A lag deposit

Question 8

The deserts found in the western United States are primarily the result of being located ________.

A)in the subtropics
B)within rain-shadows of mountains
C)near the center of a large continent
D)next to a cold ocean current

Question 9

A desert may form along a coastline because a ________.

A)warm current warms and dries the air
B)warm current forces hot air inland
C)cold current cools and dries the air
D)cold current forces hot air inland

Question 10

Deserts do not need to be in hot regions;they only need to be ________,for example,deserts can form in cold,dry,________ regions.

A)dry;tropical
B)humid;polar
C)arid;polar
D)humid;subtropical

Question 11

Physical weathering produces piles of broken rocks called ________.

A)inselbergs
B)arroyos
C)caliche
D)talus

Question 12

As shown in the figure below,wind erosion can create a faceted rock known as a ________.

A)ventifact
B)lag deposit
C)yardang
D)wadi

Question 13

Which desert is the result of air masses that dry out as they cross over land?

A)Sahara Desert
B)Atacama Desert
C)Arabian Desert
D)Gobi Desert

Question 14

Fine-grained sediment,such as dust and silt,is transported by wind in ________.

A)suspension
B)saltation
C)deflation
D)surface creep

Question 15

To qualify as a desert,a region must ________.

A)be hot,with a mean annual temperature greater than 25°C (77°F)
B)be arid,with less than 15% of the ground surface vegetated
C)have a mean annual temperature greater than 25°C and less than 5 cm annual rainfall
D)have no rainfall three out of four seasons

Question 16

Why do deserts form in polar regions?

A)Increased albedo prevents evaporation.
B)There is no vegetation to release CO₂ .
C)There are no sources of water to evaporate.
D)Cold air does not hold much moisture.

Question 17

Why do deserts form at high elevations?

A)The Sun's rays strike at a high angle.
B)The air is too dense to hold moisture.
C)The air is too thin to hold much heat.
D)Moist air is forced upward and dries out.

Question 18

According to the textbook,the highest recorded temperature on Earth was in a ________.

A)tropical rain forest in Brazil
B)low-latitude,high-elevation desert in Mexico
C)high-latitude,high-elevation desert in Mongolia
D)low-latitude,low-elevation desert in Libya

Question 19

Desert climate associated with a rain-shadow is found ________.

A)on the windward side of mountain ranges
B)on the leeward side of mountain ranges
C)in the middle of flat plains
D)along continental coastlines

Question 20

The measured rainfall shown in the figure below is characteristic of a ________ desert.

A)coastal
B)subtropical
C)rain-shadow
D)continental-interior

Question 21

Iron-rich,well-oxidized strata will be ________.

A)tan
B)gray
C)green
D)dark red

Question 22

Piles of sand that form simple,wave-like shapes are called ________ dunes.

A)barchans
B)transverse
C)star
D)parabolic

Question 23

Which of the following images is the result of sediment deposited at the mouth of a canyon?

A)A
B)B
C)C
D)D

Question 24

What is the largest particle that can be carried as part of the suspended load during wind erosion?

A)gravel
B)sand
C)silt
D)clay

Question 25

Which of the following images is the result of chemical erosion?

A)A
B)B
C)C
D)D

Question 26

An apron-shaped pile of alluvium that forms at the mouth of a canyon is known as a(n)________.

A)playa
B)sabkha
C)alluvial fan
D)inselberg

Question 27

Calcrete (caliche)forms in a desert climate through the dissolution and the reprecipitation of ________ during and after rainstorms.

A)manganese oxide
B)quartz
C)calcite
D)iron oxide

Question 28

The image below is of a ________ dune.

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

Question 29

Imagine that you come across a flat,thick layer of rock salt in an outcrop.What can you determine about the sedimentary environment in which it was formed?

A)It was an ocean.
B)It was a beach.
C)It was humid.
D)It was arid.

Question 30

Most of the erosion in desert environments is caused by ________.

A)wind
B)surface water
C)groundwater
D)salt wedging

Question 31

The process of lowering the surface of the land by wind erosion is known as ________.

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

Question 32

Desert varnish consists of ________.

A)pesticides and other pollutant residues
B)dusts of iron and magnesium oxides
C)dust deposits affected by microorganisms
D)carbonate cements with iron impurities (e.g. ,siderite)

Question 33

In the figure below,the sand grains are being transported by ________.

A)suspension
B)saltation
C)surface creep
D)deflation

Question 34

Mesas,buttes,and chimneys are all the result of ________.

A)cliff retreat
B)wind erosion
C)chemical weathering
D)deposition

Question 35

Compared with humid climates,the rates of chemical weathering in deserts are ________.

A)much faster
B)much slower
C)very similar
D)too variable to understand

Question 36

When fine-grained sediment is blown away as shown in the figure below,the coarser sediment left behind is known as ________.

A)a sabkha
B)ventifacts
C)a lag deposit
D)talus

Question 37

Why is chemical weathering relatively rare in deserts?

A)Chemical weathering requires much colder temperatures than are seen in deserts.
B)Physical weathering occurs only in hot regions,thus is more prevalent in deserts.
C)Chemical weathering only occurs in the presence of salt water from the ocean.
D)Chemical weathering most often involves reaction with water,which is rare in deserts.

Question 38

Areas with relatively scarce sand and constantly shifting winds will develop ________ dunes.

A)star
B)barchans
C)parabolic
D)longitudinal

Question 39

Which of the following is an example of wind erosion?

A)a large boulder sitting on the side of a dry streambed
B)large piles of sand that move across the desert floor
C)a fan-shaped pile of sediment at the mouth of a canyon
D)deeply eroded arroyos that cover the desert floor

Question 40

The saltation of sand involves ________.

A)spherical grains rolling along the surface of dunes
B)grains traveling short distances (approximately 1 m)in the air
C)grains traveling long distances (approximately 1-100 km)in the air by strong winds
D)the mixing of mineral sand and salt to form a weakly cemented soil

Question 41

Desertification may also be responsible for which of the following far-reaching consequences?

A)excess organic material blown over cities
B)excess salts added to the ocean
C)contamination of artic waters
D)destruction of coral reefs

Question 42

________ results from the transformation of a once-fertile area to an arid desert.

A)Desertification
B)Desert pavement
C)Deflation
D)Toxification

Question 43

The desertification of the Sahel region in Africa was the result of ________.

A)overcrowding by nomadic people
B)removal of grasses from the soil
C)drying out of the area by overpopulation
D)diversion of rivers to larger cities

Question 44

Which of the following hazards could lead to desertification?

A)climate change
B)earthquakes
C)landslides
D)flooding

Question 45

Which of the following would NOT be a cause of desertification?

A)overpopulation
B)overgrazing
C)rainfall
D)natural drought

Question 46

How do chimneys (also called hoodoos)and yardangs differ?

A)Yardangs are formed by the erosion of water,whereas chimneys are formed by evaporation.
B)Chimneys are formed by evaporation,whereas yardangs are formed by the erosion of water.
C)Chimneys are fossilized trunks of saguaro and other large cactus,whereas yardangs are not.
D)Chimneys are remnants of physical erosion,whereas yardangs are remnants of wind erosion.

Question 47

Label the images below with the name of the type of sand dune shown.

Question 48

The geometry of sand dunes is NOT strongly influenced by the ________.

A)strength of the wind
B)consistency of wind direction
C)abundance of sand
D)timing of the monsoon season

Question 49

Imagine you are a farmer moving into the Great Plains area after the Dust Bowl of 1933.What can you do to make the land fertile enough for farming again? What about grazing of livestock?

Question 50

Which of the following human activities can cause desertification?

A)addition of fertilizer to soil
B)diversion of water from an area
C)overirrigating an area
D)building a city in an area

Question 51

The Dust Bowl event in 1933 resulted from which natural event?

A)overpopulation
B)long-term drought
C)bad farming practices
D)change in the course of rivers

Question 52

Conversion of productive land to desert is known as ________.

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

Question 53

What is the dominant erosional force in deserts,wind or water? Why?

Question 54

Describe the differences between lag deposits and desert pavement.

Question 55

What is a desert? Explain how a desert could be formed at one of the poles.