Geology Chapter 19

Hot, high humidity air rising over equatorial regions: a. evaporates more water. b. heats up more as it rises. c. carries water away from the equator. d. cools as it rises and drops plentiful rainfall.

Cools as it rises and drops plentiful rainfall

Large-scale cross bedding in sandstone is strong evidence of: a. stream flow in a large river. b. glacial surge. c. debris flow. d. windblown dunes.

Debris Flow

The lowering of the ground surface by wind erosion of fine sediment is called: a. deflation. b. desert pavement. c. sand blasting. d. all of the above.

Deflation

What do we call desert surface with concentration of pebbles, underlain by windblown dust? a. desert varnish b. ventifacts c. desert pavement d. pebble road

Desert Pavement

What is the geologic term for the distinctive, dark-brown coating that forms on rock surfaces in the desert? a. desert varnish b. loess c. desert pavement d. frosting

Desert Varnish

Which of the following statements is false? a. Deserts are common near 30°N latitude. b. Deserts are common near the equator. c. Deserts are common near 30°S latitude. d. Deserts are common in large continent interiors.

Deserts are common near the Equator

Where are the largest loess deposits in North America found? a. in the southwestern deserts b. in the upper Mississippi valley c. along the Atlantic coast d. along the northern Pacific coast

In the Upper Mississippi Valley

The Gobi desert of central Asia exists primarily because of its location: a. at 30 degrees latitude. b. downwind of a coastal mountain range. c. at very high latitude. d. in the deep interior of a large continent.

In the deep interior of a large continent

Windblown dust has what effect on global climate? a. It blocks incoming visible light and lets through outgoing infrared. b. It lets through incoming visible light and blocks outgoing infrared. c. It blocks incoming visible light and blocks outgoing infrared. d. It lets through incoming visible and outgoing infrared light.

It blocks incoming visible light and blocks outgoing infrared.

Which of the following would you LEAST expect to find in a desert? a. playa lakes b. rounded, soil-covered hills c. steep river valleys and gorges d. dunes

Rounded, Soil-Covered Hills

The largest sediment grains transported by wind are: a. clay. b. silt. c. sand. d. gravel

Sand

The steeper, downwind side of a sand dune is called a: a. sand drift. b. ventifact. c. slip face. d. dip face.

Slip Face

Dunes migrate: a. downwind faster than the wind. b. slowly upwind. c. slowly downwind. d. Dunes don't move; they form in place.

Slowly Downwind

Which of the following is evidence that the northern Africa Sahara desert has had a more humid climate in the last 10,000 years? a. Stream channel network buried under sand dunes. b. Lake bed sediments cover much of the desert. c. Soil covers many of the dunes. d. None of the above.

Stream channel network buried under sand dunes

High velocity of wind is necessary to: a. suspend larger (sand) particles. b. carry particles higher. c. suspend particles longer. d. carry particles farther.

Suspend larger (sand) particles

Wind-faceted pebbles with curved or flat faces meeting at sharp edges are: a. artifacts. b. ventifacts. c. wind gravel. d. desert varnish.

Ventifacts

Erosion in deserts is dominated by: a. wind. b. water. c. mass wasting. d. approximately equal contribution by wind and water.

Water

At 30-50 latitudes, prevailing surface winds are from the: a. East. b. West. c. North. d. South.

West

Frosted, sand-sized quartz grains are indicative of sand transported by: a. wind. b. streams. c. glaciers. d. mass wasting.

Wind

Which of the following statements is true? a. Wind is a more effective erosion agent in wet climates. b. Wind is a more effective erosion agent in dry climates. c. Wind is an equally effective erosion agent in wet and dry climates. d. Wind is not capable of erosion.

Wind is a more effective erosion agent in dry climates

Saltating sand grains rise to: a. greater heights in air than in water. b. greater heights in water than in air. c. approximately the same height in air and in water. d. Air doesn't move sand grains.

greater heights in air than in water.

In desert regions: a. physical weathering predominates over chemical weathering. b. chemical weathering predominates over physical weathering. c. no weathering occurs. d. both weathering types are approximately equal in strength.

physical weathering predominates over chemical weathering.

In a large dust storm, approximately how much dust can 1 cubic kilometer of air carry? a. 100 pounds b. 10 tons c. 1000 tons d. 10,000 pounds

1000 tons

Arid regions make up approximately what percentage of the continents? a. 10 b. 20 c. 35 d. 45

20

The Sahara, Kalahari, and Great Australian deserts each receive an average of less than _________ mm of rain per year. a. 10 b. 25 c. 50 d. 100

25

How high are the highest sand dunes in the world? a. 25 meters b. 250 meters c. 2500 meters d. 1000 meters

250 Meters

Which of the following statements is true? a. Air has higher density than water. b. Air has higher viscosity than water. c. Airflows are nearly always turbulent. d. Airflows are nearly always laminar.

Airflows are nearly always turbulent.

Dune sand is stabilized by: a. barriers protecting sand from wind. b. establishment of vegetation. c. increased cohesion of damp sand. d. all of above.

All of Above

The mass of material transported by wind depends on: a. wind velocity. b. particle size. c. surface material over which wind blows. d. all of above.

All of Above

Causes of desertification include: a. overgrazing. b. overly intensive cultivation. c. felling of trees and brushwood for fuel. d. all of the above.

All of the Above

Sand dune shape is dependent on: a. wind direction. b. wind duration. c. wind strength. d. all of the above.

All of the Above

Which of the following are contributions of irrigation to desertification? a. Using wells for irrigation water uses groundwater faster than it is replenished. b. Using rivers for irrigation can deplete groundwater recharge. c. Evaporation of irrigation water causes salts to be deposited in soils. d. All of the above.

All of the Above

Dunes with crescent shape and horns in the downwind direction are called: a. barchans. b. blowout. c. transverse. d. longitudinal.

Barchans

Volcanic dust is an abundant component of dust in the atmosphere because: a. it is very fine grained. b. it erupts high into atmosphere. c. there is more of it than other dust. d. both A and B.

Both A and B

Dunes form where: a. wind removes dust and gravel. b. there is a plentiful supply of sand. c. strong winds pile up loose, dry sand. d. both B and C.

Both B and C

A wadi is a(n): a. arcuate-shaped sand dune. b. dry wash in the desert. c. shallow, temporary lake in the desert. d. cut off meander.

Dry Wash in the Desert

Geologic processes powered by wind are called ___ processes. a. eolian b. alluvial c. fluvial d. glacial

Eolian

The slope of the downwind side of a sand dune is _________ the angle of repose. a. greater than b. equal to c. less than d. none of the above

Equal to

Another term for dune field is: a. pediment. b. dry wash. c. erg. d. alluvial fan.

Erg

Given enough sand and wind, where will a dune start to form? a. anywhere b. only on steep mountain slopes c. in a wind shadow formed by an obstacle d. none of the above

In a wind shadow formed by an obstacle

The slope of the upwind side of a sand dune is _________ the angle of repose. a. greater than b. equal to c. less than d. none of the above

Less than

. A primary reason for the locations of the Great Basin and Mojave deserts is: a. latitude about 30 degrees. b. location in rain shadow of coastal mountain range. c. deep interior of large continent. d. coastal region at the equator.

Location in Rain Shadow of Coastal Mountain Range

A blanket deposit of windblown dust is a: a. transverse dune. b. loess. c. graded bed. d. till.

Loess

Which of the following deposits consists of fine-grained dust? a. barchan b. loess c. pediment d. till

Loess

Which of the following landforms is characteristic of the desert? a. levee b. pediment c. sandstone d. terrace

Pediment

Where would you expect to find evaporite sediments in a desert environment? a. playa lake b. alluvial fan c. dune field d. terrace

Playa Lake

What was a major contributor to Australia's change from a warm, humid climate to a desert interior in the last 20 million years? a. The continent has doubled in size. b. A bounding mountain range has formed. c. The continent has moved north into the arid subtropical zone. d. None of the above.

The continent has moved north into the arid subtropical zone

What types of dunes are oriented at right angles to the wind direction? a. barchan b. linear c. transverse d. perpendicular

Transverse

Saltation of sand is: a. a rolling and sliding motion that suspends sand in a current of water or air. b. suspension of sand in the lower atmosphere. c. suspension of sand in the upper atmosphere. d. a bouncing and rolling "jumping" motion that suspends sand in a current of water or air.

a bouncing and rolling "jumping" motion that suspends sand in a current of water or air.

Major deserts occur at about 30 degrees north and south latitude because: a. most rainfall is over the ocean at this latitude. b. hot humid air rises at this latitude taking away the moisture. c. cool dry air falls to the surface at this latitude, evaporating moisture as it is heated. d. major deserts don't occur at this latitude.

cool dry air falls to the surface at this latitude, evaporating moisture as it is heated.