Gly Test 3 Practice Ch 19

1. Desert and steppe lands cover about what percentage of Earth's land area?

10%

66%

30%

3%

2. Most dry lands lie between ________ degrees north and south of the equator.

40 and 50

20 and 30

5 and 10

0 and 5

3. Assume that the central slip face of a barchan dune slopes downhill toward the east. What is the direction of the prevailing wind?

East to west

North to south

South to north

West to east

4. ________ dunes are long, high, sand dunes parallel with the prevailing wind direction.

Transducinal

Longitudinal

Latitudinal

Transversal

5. ________ dunes result from persistent, onshore winds in certain coastal areas.

Diabolic

Barchanoid

Parabolic

Staroid

6. ________ have rainfall amounts and soil moisture contents between those of true deserts and humid lands.

Tundras

Steppes

Sundras

Sabkhas

7. Which one of the following would probably not affect the size and depth of a blowout?

A rise in sea level

The near surface water table

Type and density of vegetation

Areas of desert pavement

8. Rainshadow deserts are common in ________.

Vast, dry, steppe lands like the Great Plains

North central Africa

The dry valleys of eastern California and Nevada

Europe north of the Alps

9. Which one of the following is a low-latitude desert characterized by high atmospheric pressures and descending air masses (not rain shadow deserts).

Sahara Desert; northern Africa

Atacama Desert in Chile, South America

Gobi Desert, China and Mongolia

Desert valleys of the Great Basin, U.S.

10. ________ refers to the "bouncing" mode of sand transport in a windstorm or stream.

Saltation

Ventifaction

Siltation

Deflation

11. Which one of the following concerning desert lands is false?

Less than 30 percent is covered with dunes and drifting sand.

Wind erosion and deposition are important processes.

Running water has little effect on shaping the landscape.

Most desert areas are characterized by descending wind patterns.

12. How are sand grains transported by the wind?

High in the moving air column as suspended load

By saltation in the first few meters above the land surface

By deflation of abraded desert pavement

By being picked up in swirling dust clouds and carried to distant blowouts

13. A ________ is a crescent-shaped dune whose tips point downwind.

Parabarcal

Transverse

Barchan

Star

14. How is desert pavement formed?

Deflation and sheet wash remove fine-sized materials leaving coarse, weathered, rockfragments concentrated at the surface.

Blowing wind removes fine-size soil particles; coarser particles abrades to sand size.

Running water deposits gravel and sand over the finer-sized soil particles.

Intense chemical weathering removes the sand- and silt-sized particles, leaving coarse rockdebris covering the land surface.

15. What mature, desert landscape feature consists of coalesced alluvial fans?

Balda

Bajada

Bahia

Baja

16. Which one of the following statements is correct?

Alluvial fans typically rim desert valleys; playas form in the lowest, interior parts of the valleys.

Inselbergs are low, circular depressions on gently sloping pediments and bajadas.

Playas are typically covered with gravel-sized desert pavement and loess deposits.

Saline sediments and evaporites are common in inselbergs and pediments of desert landscapes.

17. Which one of the following will effectively limit further deflation in a given area?

Sea level

Desert pavement

A hanging valley

The repose level

18. How is desert pavement formed?

Deflation removes the coarse fragments leaving behind a layer of loess.

Alluvial fans are eroded to form inselbergs with rocky surfaces.

Groundwater in an alluvial fan evaporates, leaving behind a surface layer of hard-baked mud.

Runoff and deflation carry off the silt and clay, leaving coarser particles behind.

19. Which one of the following is the one best measure of the wetness or dryness of a region?

Total annual precipitation

Mean annual temperature

Difference between annual precipitation and evaporation potential

Percentage of precipitation that falls during the summer months

20. A ________ is an intermittent stream channel in the dry land areas of the western United States.

Rivulet

Playa

Rill

Wash

21. Which of the following characteristics would suggest geologically recent, fault uplift of a desert mountain range?

Flat, upland surfaces, steep slopes and small alluvial fans

Extensive pediments and bajadas and small, deep playas

Inselbergs, extensive pediments and flat valley floors

Steep playas with extensive, bedrock alluvial fans and numerous sand dunes

22. Which of the following best describes the climatic factors that cause low latitude deserts like the Sahara in Africa?

Cool, dry air aloft is descending; surface winds are blowing toward the equator.

Warm, humid air aloft is descending; surface winds blow away from the equator.

Warm, humid air is rising; surface winds are calm.

Cool, dry air at the surface is rising causing winds to blow away from the equator.

23. Which one of the following statements concerning rock weathering is true?

Warm temperatures and high soil moisture contents accelerate chemical weathering.

Low temperatures and high soil moisture contents accelerate chemical weathering but inhibitmechanical weathering.

Warm temperatures and low soil moisture contents both promote rapid rates of mechanicalweathering.

Temperature has no effect on rock weathering.

24. Loess deposits in the central United States ________.

Blew in from the dry areas in the Great Plains and southwestern desert areas

Originated as rock flour in Pleistocene glacial streams and rivers

Accumulated from flooding of the Mississippi River

Were originally deposited as barchanoid dunes and later redeposited by glaciers

25. ________ are both dry land, erosional features cut from bedrock.

Inselbergs and barcanoids

Pediments and playas

Bajadas and blowouts

Pediments and inselbergs

26. Desertification has been particularly well documented over the past 50 years in ________.

The Empty Quarter of the Arabian Peninsula

The Sahel along the southern margin of the Sahara Desert

The Dust Bowl states of the Great Plains

The steppe lands of southern Russia, Ukraine, and Kazakhstan

27. Which of the following statements concerning dry lands is not true?

Precipitation totals are low; dew points are lower in the summer than winter.

Evaporation potential exceeds actual precipitation.

Storms are infrequent and rainfall amounts are highly variable.

Wind is the dominant agent of erosion and sediment transport.

28. During a typical sandstorm, saltating sand grains reach a maximum height of ________ above the land surface.

1 inch

2 meters

10 centimeters

40 feet

29. In which area would surface water most effectively infiltrate into the local groundwater system?

A stream in a steep-sided, bedrock canyon in the mountains

Streams flowing in the numerous channels of an alluvial fan

A playa lake with a thick mud bottom

All of the above would promote infiltration.

30. Deposition of glacial rock flour from blowing winds is responsible for ________.

Deflation ventifacts

Blowout pavement

Star steppes

Loess deposits

31. Which one of the following statements is true?

Desert landscapes are monotonous, relatively flat areas covered to various depths with sand.

Deserts and dry lands are concentrated in areas of ascending air masses and relatively lowatmospheric pressures.

Despite infrequent rainfalls, erosional and depositional features of running water are importantin desert landscapes.

Rainshadow deserts occur where air masses descend after first having risen to cross a mountainrange.

32. Which one of the following is determined by the angle of repose for dry sand?

Longitudinal dune gradient angle

Slope of an alluvial fan

A vertical cut bank in loess

Inclination angle of a dune slip face

33. A ________ is formed by abrasion of rocks by windblown sand.

Playa

Ventifact

Pediment

Desert pavement

34. Which one of the following statements about sand dunes is correct?

A dune migrates in the direction of inclination of the slip face.

The more gently sloping surface is the leeward slope of the dune.

Sand is blown up the slip face and rolls down the more gently sloping flank of the dune.

In a sand dune, the more gently inclined strata lie parallel to the slip face.

35. Inselbergs are ________.

Insulated icebergs floating in a hot spring

Blowouts cut from bedrock in mountainous areas

Lithified rock formed by cementation of wind-deposited, dune sands

Bedrock hills in a highly eroded desert landscape