Introduction to Earth Science

1. Dry regions comprise approximate what percent of Earth's land area?
a. 5%
b. 15%
c. 30%
d. 45%

2. Why are most middle-latitude deserts located where they are?
a. They coincide with zones of subtropical highs.
b. No rivers run through them.
c. They are far removed from oceans.
d. They receive too much sunlight.
e. All of the above. 

3. What is the name for a dry region that occurs on the downwind side of a mountain range (or high volcano) that partially blocks the flow of moist air, forcing precipitation on the prevailing windward side, and creates more arid conditions on the downwind side:
a. rainshadow.
b. alluvial fan.
c. playa. 
d. tundra.

4. Semiarid, grass-covered regions that often surround deserts are called:
a. tundra.
b. plains.
c. plateaus.
d. steppe.
e. piedmont.

5. What is responsible for most erosion in deserts?
a. wind.
b. running water.
c. glaciers.
d. plants and animals.
e. groundwater.

6. Erosional features in desert regions formed from running water include all of the following except:
a. badlands.
b. canyons and arroyos.
c. pediments.
d. dunes. 

7. Streams that are usually dry are called:
a. effluent. 
b. alluvial.
c. ephemeral.
d. base level.

8. A gently inclined ancient erosional surface carved into bedrock that has typically developed at the foot of mountains, and may locally covered with thin deposits of stream gravel, and soil, is called: 
a. an arroyo.
b. a pediment.
c. an inselberg.
d. a desert pavement.

9. Where are you most likely to find the most coarse-grained sediments on a bajada?
a. upper alluvial fan deposits
b. mid alluvial fan deposits
c. lower alluvial fan deposits
d. a trunk stream or playa

10. What is the name for a hardened zone in soils and surficial deposits found in semiarid regions where of calcium carbonate and possibly other carbonates, clay minerals, or crystalline salts such as gypsum (CaSO4), halite (sodium chloride), sodium nitrate, and other salts impregnated the pore spaces in the sediment or soil?
a. caliche
b. hard pan
c. salt pan
d. playa

11. What is the name of the ancient lake that filled Death Valley by as much as 800 feet deep during the last ice age?
a. Mono Lake
b. Lake Panamint
c. Lake Bonneville
d. Lake Manly

12. Which of the following constitutes most of the bed load carried by wind in desert regions?
a. boulders
b. sand
c. fine dust particles
d. pebbles

13. Which type of desert erosion consists of the lifting and removal of loose material?
a. ventifact
b. deflation
c. abrasion
d. Desert pavement

14. Loess is:
a. found in areas downwind of deserts and glacial outwash plain regions.
b. an extensive blanket of silt.
c. sediment that was carried in suspension by wind. 
d. all of the above. 

15. The largest arid region in North America is:
a. the Sonoran Desert.
b. the Chihuahuan Desert.
c. the Colorado Desert.
d. the Mojave Desert.
e. the Colorado Plateau.