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Chapter 19 - Wind and Deserts
1. Eolian (i.e. desert) processes are powered by ______.
A) glaciers
B) ocean currents
C) streams
D) wind
2. Due to the Coriolis effect, any large-scale current of air or water is deflected to the _______ in
the northern hemisphere and to the _______ in the southern hemisphere.
A) left, left
B) left, right
C) right, left
D) right, right
3. Most windblown sand consists of ______.
A) calcite
B) feldspar
C) gypsum
4. Which of the following retards deflation?
A) construction
B) motor vehicles
D) quartz
C) plowing
5. What causes most of the erosion in deserts?
A) groundwater
B) streams
C) thermal cycling
D) vegetation
D) wind
6. Why are streams able to move larger particles than wind?
A) Air has a lower density and viscosity than water.
B) Air does not obey the same laws of motion as water.
C) Air moves at lower velocities than water.
D) Air impedes the bounding movements of saltation.
7. How do ventifacts form?
A) by dissolution by dew
B) by the breaking apart of rocks along cracks
C) by sandblasting
D) by slow chemical weathering
8. What type of environment yields quartz sand grains that are rounded and frosted?
A) an eolian environment
C) a glacial environment
B) an oceanic environment
D) a stream environment
9. What is the primary cause of frosting present in the surface of quartz sand grains in the desert?
A) abrasion by air currents
C) chemical reaction with feldspar grains
B) dissolution by dew
D) impacts with other sand grains
10. Which of the following processes does not increase the amount of dust in the atmosphere?
A) agriculture
B) deforestation
C) erosion
D) precipitation
11. How much of the Sahara desert is covered with sand and sand dunes?
A) approximately 1%
C) approximately 50%
B) approximately 10%
D) approximately 90%
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12. Which of the following best explains why the Sahara desert of Africa exists?
A) The Sahara desert lies in the rain shadow of coastal mountains.
B) The Sahara desert lies near 30°N latitude.
C) The Sahara desert lies thousands of kilometers from the ocean.
D) The sandy soil of the Sahara desert drains so quickly that vegetation is unable to grow.
13. How does desert pavement form?
A) by intense chemical weathering
B) by stream erosion
by intense mechanical weathering
by wind erosion
14. Which of the following is a coarse, gravelly ground surface that results from the removal of
fine-grained particles by wind erosion?
A) alluvial fan
B) desert pavement
C) pediment
D) talus slope
15. Which of the following processes describes the gradual erosion of the ground surface by wind?
A) deflation
B) desertification
C) solifluction
D) subsidence
16. Sand will accumulate _______ of a boulder.
A) mostly on the leeside (downwind)
B) mostly on the windward side (upwind)
C) equally on the leeside and the windward side
D) neither on the leeside nor on the windward side
Use the following to answer question 17:
17. Given the relative positions of the sand dune and rock shown above, the wind direction is
predominantly _______________.
A) north to south
B) south to north
C) east to west
D) west to east
18. What type of sedimentary deposit results from the settling of fine-grained particles from a dust
A) loess
B) playa
C) pediment
D) sand dune
19. During erosion, loess tends to break off __________.
A) in horizontal layers
C) in vertical sheets
B) along irregular cracks
D) slowly, grain-by-grain
20. The loess deposited in the Upper Mississippi Valley was derived primarily from __________.
A) coastal sand dunes
C) desert regions lying to the west
B) glacial deposits
D) volcanic dust
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