Chapter 7

What is the main type of weathering in deserts?

physical weathering

What force causes most of the erosion in desert areas?

running water

What is the moraine called that marks the farthest advance of a glacier?

terminal end moraine

How does wind transport sand grains?

by saltation as part of the bed load

Icebergs are produced when large pieces of ice break off from the front of a glacier during a process called

calving

Abrasion changes the desert surface by

cutting and polishing exposed rock surfaces

Desert pavement is created as a result of

deflation

In desert areas, what process results in the formation of a desert pavement?

deflation

The weathered debris in deserts consists mainly of

unchanged rock and mineral fragments

Which of the following is true about ice sheets?

They flow in all directions.

Currently, about what percent of Earth's land surface is covered by glaciers?

10%

During the most recent ice age, what percentage of Earth's surface was covered by glaciers?

30%

Sand dunes that form scalloped rows of sand at right angles to the wind are called

barchanoid dunes

Which of the following is NOT true about glaciers?

They exist only in the Northern Hemisphere

Why can a heavy rain shower cause a large amount of erosion in a desert area?

There is a lack of vegetation to hold the soil in place.

Which of the following statements is NOT true about weathering in deserts?

There is no chemical weathering in deserts.

What is a blowout?

a shallow depression caused by deflation

A cone of debris deposited by running water at the mouth of a canyon in an arid area is known as a(n)

alluvial fan

he rust-colored tint of some desert landscapes is the result of

chemical weathering

A bowl-shaped depression at the head of a glacial valley is a(n)

cirque

In Figure 7-2, which diagram illustrates barchan dunes?

diagram A

In Figure 7-2, which diagram illustrates the dune types that would form if the prevailing winds were steady, sand supply was plentiful, and vegetation was sparse?

diagram B

In Figure 7-2, which diagram illustrates longitudinal dunes?

diagram D

What features are labeled A in Figure 7-1?

drumlins

What feature is labeled B in Figure 7-1?

end moraine

What features, illustrated in Figure 7-1, were deposited by streams flowing in tunnels beneath the ice?

eskers

Which one of the following is NOT an effect that Pleistocene glaciers had on the landscape?

extinction of the dinosaurs

What is the term for all sediments of glacial origin?

glacial drift

A thick ice mass that forms over the land from the accumulation, compaction, and recrystallization of snow is a

glacier

The thick loess deposits in South Dakota, Nebraska, and Iowa

had their source as glacial sediments

The Antarctic Ice Sheet in the Southern Hemisphere

holds almost two-thirds of Earth's fresh water

Where do glaciers form?

in areas where more snow falls than melts

Over time, sand dunes tend to migrate

in the same direction as the wind blows

When wind creates a sand dune, the sheltered side of the dune

is steeper than the windward side

What features are labeled F in Figure 7-1?

kettle lakes

Windblown silt that blankets a landscape is called

loess

Long sand ridges that are oriented more or less parallel to the prevailing wind are called

longitudinal dunes

Deflation affected the Dust Bowl in the 1930s by

lowering the land

In the desert environment, the chemical weathering of rocks is generally reduced because

moisture is lacking and organic acids are scarce

If the steep face of a sand dune is on the southeast side of the dune, then the prevailing wind in this area is from the

northwest

What feature is labeled G in Figure 7-1?

outwash plain

Dunes whose tips point into the wind are called

parabolic dunes

Dry, flat lake beds located in the center of basins in arid areas are called

playas

The loosening and lifting of blocks of rock by glaciers is called

plucking

In the desert, ephemeral streams

run only after it rains

Which of the following features was formed by glacial erosion?

the Great Lakes

One characteristic of glacial movement is that

the movement depends on the balance between accumulation and wastage

Material deposited directly by a glacier is called

till

Which of the following is NOT deposited by wind?

till

The action of abrasion can best be described as

windblown sand cutting and polishing exposed rock surfaces

What is the zone above the snowline on a glacier called?

zone of accumulation