Test #4- Chapter 15

Which of the following is true of loess deposits?

They are formed of fine-grained clays and silts

A desert is an area in which potential evapotranspiration rates exceed actual evapotranspiration rates.

True

The sandblasting action of wind-blown particles is called...

abrasion

About ____ area of desert areas are covered with sand?

10%

Clay is easy to lift from a surface and also is easy to keep suspended in the air.

False

In China, the desert pavements are called...

Gobi

Which side of a dune typically has a slope angle equal to that of the angle of repose for sand?

Leeward side

The spatial distributions of Earth's dry regions are attributable to all of the following factors except...

The equatorial low pressure region and the ITCZ

The formation of desert pavement involves both wind and water.

True

The rate of sand movement is proportional to the wind speed.

True

The saltating particles can initiate the movement of other particles.

True

The skipping and bouncing action of saltation accounts for about 80% of wind transported particles.

True

The suspension of finer particles by wind over significant distances is a phenomenon known as...

a dust storm

List three classes of dune forms...

crescentic (crescent shaped), linear, and star

Removal of vegetation from a semiarid grassland environment is likely to lead to...

deflation

The removal and lifting of individual loose particles by the wind is termed...

deflation

Which two processes create desert pavement?

deflation and rain wash

The term eolian refers to...

erosion, transportation, and deposition by the wind

If precipitation events occur in a desert, a dry stream-bed can fill with a torrent called ______ and the dry stream-bed is known as a ______.

flash flood; wash

The ability fo the wind to move materials

is small compared to other transporting agents, such as water and ice

Desert landscapes tend to be ____ in appearance because of the ______...

rugged and hard-edged; lack of water erosion

Pebbles can be moved by _____ in a process known as _______.

saltating particles; surface creep

Elongated, streamlined ridges aligned parallel to the most effective wind direction are called...

yardangs

Which of the following is not true of alluvial fans? A. They often serve as good sources of groundwater B. They frequently occur in the eastern US C. The largest sized sediment is found near the top of the fan, and the smallest near the bottom D. They are depositional features

B. They frequently occur in the eastern US

Which of the following grain sizes is most readily moved by the wind? A. large B. intermediate C. small D. grain size dose not affect the wind erosion

B. intermediate

Which of the following surface conditions wold limit the effectiveness of wind as an erosional agent? A. surface materials that are noncohesize B. surface materials consisting of clay-sized particles C. surface material that are dry D. surface covered with little or no vegetation

B. surface materials consisting of clay-sized particles

Desertification is caused by... A. poor agricultural practices B. deforestation C. global climate changes D. all of the above

D. all of the above (poor agricultural practices, deforestation, and global climate changes)

What size material comprises the dust in a dust storm that extends thousands of feet above the ground?

silts and clays

In which region of the U.S. are eolian processes most effective?

southwest

Desert pavement refers to...

surfaces of concentrated pebbles and gravels