Dry Regions The Geology of Deserts Ch17 Complete Test Bank - Geology Essentials 6e Complete Test Bank by Stephen Marshak. DOCX document preview.
CHAPTER 17: Dry Regions: The Geology of Deserts
LEARNING OBJECTIVES
17A. Define the term desert and characterize factors that cause regions to have deserts.
17B. Explain how weathering and erosional processes in deserts differ from those in temperate lands.
17C. Describe the processes that lead to deposition of sediment in deserts.
17D. Describe distinctive landforms and landscapes of deserts, and explain how they form.
17E. Discuss how human activity may transform vegetated regions into deserts.
MULTIPLE CHOICE
1. Deserts represent ________ of the Earth’s land surface.
a. | less than 5 percent | c. | about 25 percent |
b. | about 10 percent | d. | more than 50 percent |
2. 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 percent 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 |
3. The highest recorded temperatures on the Earth occur in
a. | mid-latitude, rain shadow deserts. |
b. | mid-latitude, continental interior deserts. |
c. | low-latitude, low-elevation rainforests. |
d. | low-latitude, low-elevation deserts. |
4. Desert climates associated with a rain shadow are 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 |
5. Coastal region deserts are most likely to occur along coastlines adjacent to ________ ocean currents.
a. | warm | c. | upwelling |
b. | cold | d. | nutrient-rich |
6. The Atacama Desert in Chile is a desert primarily because it is located ________.
a. | in the subtropics |
b. | near the South Pole |
c. | near the center of a large continent |
d. | next to a cold ocean current |
7. The Gobi in Mongolia is a desert primarily because it is located ________.
a. | in the subtropics |
b. | in a polar region |
c. | near the center of a large continent |
d. | next to a cold ocean current |
8. What is the main feature of atmospheric circulation at 20° to 30° north and south latitude?
a. | Cool, dry air sinks, becoming drier as it heats up. |
b. | Warm, moist air rises, increasing in relative humidity as it rises. |
c. | Warm, dry air rises, becoming cooler. |
d. | Cool moist air sinks, providing abundant rainfall. |
9. The Great Basin deserts found in the western United States are primarily the result of being located ________.
a. | in the subtropics |
b. | within the rain shadow of one or more mountain ranges |
c. | near the center of a large continent |
d. | next to a cold ocean current |
10. The definition of a desert depends on a region’s ________.
a. | latitude | c. | aridity |
b. | elevation | d. | temperature |
11. 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 |
12. Much of the land area north of the Arctic Circle is considered to be a desert because
a. | summer temperatures can get very hot. | c. | it is extremely arid. |
b. | the Arctic Ocean provides cold water currents. | d. | there is no rain; only snowfall. |
13. The figure below illustrates the formation of a ________.
a. | coastal desert | c. | rain-shadow desert |
b. | subtropical desert | d. | continental-interior desert |
14. Continental interior deserts occur because
a. | there are no rivers in the interior of continents to provide water vapor. |
b. | air masses lose much of their moisture before reaching continent interiors. |
c. | continent interiors are located at low latitudes where air rises. |
d. | atmospheric circulation in the interior of continents is characterized by dry sinking air masses. |
15. Isolated mountains that stick up above large expanses of desert alluvium are called
a. | inselbergs | c. | mesas |
b. | playas | d. | desert pavement |
16. The colors of the landscape in desert regions are controlled by ________.
a. | what type of desert it is | c. | the season of the year |
b. | the air temperature | d. | the composition of the bedrock |
17. Caliche and calcrete are terms for
a. | economically important cement mineral resources mined from desert regions. |
b. | unique desert soils where grains of regolith are cemented together. |
c. | dark mineral deposits that develop on rock exposures in deserts. |
d. | faceted rocks carved by wind erosions in desert landscapes. |
18. Why is water a very effective agent of erosion in deserts?
a. | The action of running water is not lessened by vegetation cover in deserts. |
b. | The hotter water temperature in deserts carries more energy. |
c. | Deserts have many more small streams than other landscapes. |
d. | Slopes are steeper in deserts, making running water more powerful. |
19. Many desert streams are ephemeral, meaning
a. | they are supplied by groundwater and not by rainfall. |
b. | they only carry water after rainfall events, and most of the time they are dry streambeds. |
c. | they only occur on north-facing slopes. |
d. | they quickly evaporate when the sun is shining. |
20. The petroglyph in the image below is carved into _______, revealing the lighter-colored bedrock underneath.
a. | basalt | c. | caliche |
b. | desert varnish | d. | salt |
21. Fine-grained sediments such as dust and silt can stay in the air and be transported by wind as ________.
a. | suspended load | c. | deflation clasts |
b. | saltation | d. | desert varnish |
22. The process of lowering the land surface by wind erosion is known as ________.
a. | saltation | c. | desertification |
b. | deflation | d. | escarpment |
23. Most of the erosion in desert environments is caused by ________.
a. | wind | c. | groundwater |
b. | surface water | d. | salt wedging |
24. In the figure below, the sand grains are being transported by ________.
a. | suspension | c. | surface creep |
b. | saltation | d. | deflation |
25. The figure below demonstrates the formation of a surface layer of coarse material on the surface in deserts called
a. | a blowout deposit. |
b. | a lag deposit. |
c. | an arroyo. |
d. | badlands. |
26. What is a ventifact?
a. | a bowl-like depression carved by wind |
b. | an exposed rock with facets carved by wind |
c. | a tool left by former civilizations that lived in deserts |
d. | coarse-grained sediments that are not carried in desert dust storms |
27. Playas are important resources for minerals such as
a. | feldspar. |
b. | olivine. |
c. | borax. |
d. | quartz. |
28. Wind-carved elaborate mounds and ridges are termed ________.
a. | mirages | c. | sabkhas |
b. | caliches | d. | yardangs |
29. What is talus?
a. | thick crusts of cemented soil | c. | the formal term for sand dunes |
b. | angular rocky debris at the base of a cliff | d. | rocks with faceted faces abraded by wind |
30. Which letter corresponds to talus in this image?
a. | A |
b. | B |
c. | C |
d. | D |
31. The slope of a pile of talus is typically _______ than the slope of an alluvial fan.
a. | less irregular | c. | steeper |
b. | less steep | d. | more stable underfoot |
32. Alluvial fans accumulate in deserts at the mouth of ________
a. | canyons | c. | playas |
b. | sand dunes | d. | talus slopes |
33. Which of the following describes sediment deposition in alluvial fans?
a. | It is where streams in valleys are dammed by large mountains. | c. | It is where dunes pile sediment against the base of a mountain. |
b. | It is where streams sink into the subsurface and drop their sediment load. | d. | It is where the slope of the stream decreases and the water slows. |
34. Why are salt lakes salty?
a. | because desert streams carry very salty water | c. | because evaporation from the lakes removes water but not salt |
b. | because mineral springs deliver salt water to such lakes | d. | because rainfall in deserts is salty |
35. Talus aprons represent accumulations of ________.
a. | angular debris at the base of a hill |
b. | lag deposits |
c. | coarse sediment in a deflation basin |
d. | loess at the edge of a desert |
36. A salt-rich flat lake bed in called a
a. | wadi. | c. | playa. |
b. | pediment. | d. | bajada. |
37. A(n) ________ consists of sand and gravel deposited by ephemeral distributary channels that occur where a gully or a canyon discharges from its mouth.
a. | alluvial fan | c. | wadi |
b. | ventifact | d. | yardang |
38. Over time, alluvial fans may merge to form a ________.
a. | wadi | c. | playa |
b. | talus apron | d. | bajada |
39. Where would you go among the following to find a salt lake?
a. | Florida | c. | Michigan |
b. | Utah | d. | Hawaii |
40. A mesa is most likely to form if the underlying bedrock is
a. | folded sedimentary rock. | c. | flat-lying sedimentary rock. |
b. | fault-tilted sedimentary rock. | d. | igneous rock. |
41. The geometry of sand dunes is NOT strongly influenced by the ________.
a. | strength of the wind | c. | abundance of sand |
b. | consistency of wind direction | d. | timing of the monsoon season |
42. Areas with relatively scarce sand and constantly shifting winds will develop ________ dunes.
a. | star | c. | parabolic |
b. | barchan | d. | longitudinal |
43. The movement of sand up the windward face of a dune and down the slip face causes
a. | cross-bedding. | c. | desert pavement. |
b. | caliche. | d. | dust storms. |
44. The Sahel is a semiarid grassland south of the Sahara Desert that is experiencing
a. | depopulation. |
b. | loss of desert pavement. |
c. | desertification. |
d. | seasonal flooding. |
45. Plowing soil and overgrazing by livestock in arid regions can contribute to
a. | loss of sand dunes. |
b. | growth of desert varnish. |
c. | accelerated soil erosion. |
d. | decreases in precipitation. |
46. Where in the United States were people affected by desertification during the Great Depression of the 1930s?
a. | Appalachia |
b. | New England |
c. | Alaska |
d. | the western Great Plains |
47. Conversion of productive land to desert is known as ________.
a. | deflation | c. | degradation |
b. | saltation | d. | desertification |
48. Why is the dust derived from desert erosion a challenge to public health?
a. | It suffocates plants that are downwind. | c. | It contains carbon monoxide. |
b. | It can carry salts and toxic metals. | d. | It reduces the oxygen in air. |
49. Which of the following hazards could lead to desertification?
a. | climate change | c. | landslides |
b. | earthquakes | d. | flooding |
50. Which of the following human activities will lead to desertification?
a. | addition of fertilizer to soil | c. | over-irrigating an area |
b. | overgrazing by livestock in an area | d. | building a city in an area |
1. What is a desert? Explain how a desert could be formed at one of the poles.
2. Illustrate how a rain-shadow desert might form.
3. What is the dominant erosional force in deserts: wind or water? Why?
4. What is desert varnish? How does it form? Why doesn’t one find desert varnish in humid climates?
5. Why are flash floods so effective at transporting sediment?
6. Contrast a lag deposit and desert pavement.
7. Why is the Great Salt Lake in Utah so salty?
8. Explain the global-scale pattern of atmospheric circulation that leads to the formation of subtropical deserts.
9. How can overpopulation contribute to desertification of a landscape?
10. Imagine you are a farmer moving into the Great Plains area after the Dust Bowl of the 1930s. What can you do to make the land fertile enough for farming again? What can be done to prevent a similar disaster from happening again?