Chapter 21 test review

Soil is a mixture of weathered rock, mineral fragments,
water, air and ____.
a. sand c. moss

b. decayed organic matter d. clay

The layer of soil that contains the most organic material

is called the ____ horizon.
a. A c. C

b. B d. D

All of the following cause mechanical weathering EXCEPT

a. ice c. burrowing animals

b. tree roots d. carbonic acid

Litter often covers the ____ horizon.

a. A c. C

b. B d. all of the above

Chemical weathering is more rapid in a ____ climate.

a. warm, dry c. cold, dry

b. warm, wet d. cold, wet

Mechanical weathering is more rapid in a ____ climate.

a. dry c. cold

b. hot d. humid

The organic matter in humus is made of ____.

a. dead worms c. roots

b. stems d. all of the above

The rate of weathering depends upon the area’s ____.

a. oxygen c. water

b. climate d. soil

The rock and mineral fragments in soil come from rock

that has been ____.

a. blasted

b. carved

c. weathered
d. chemically treated

The difference between mechanical and chemical

weathering is ____.

a. the length of time each takes to break up a rock

b. that only chemical weathering involves water

c. the way they affect the makeup of a rock

d. all of the above

Soils in ____ contain little organic material and are thin

a. tropical areas c. prairies

b. deserts d. temperate forests

Plants cannot grow without ____.

a. rocks c. moss

b. soil d. pesticides

The mass of clay, silt, sand, and boulders that covers

much of the United States was deposited by ____.

a. farming c. ice wedging

b. glaciers d. huge bulldozers

Minerals found in the B horizon were dissolved in water

and carried there by a process called ____.

a. oxidation c. weathering

b. leaching d. littering

Oxidation occurs when materials containing ____ are

exposed to oxygen and water.

a. iron c. kaolinite

b. carbonic acid d. all of the above

The B horizon is ____.

a. rockier than the C horizon c. lighter than the A horizon

b. richer in humus than the A

d. thinner than the C horizon

Plants don’t grow as well when ____ has been lost.

a. clay c. parent rock

b. topsoil d. slope

____ is a factor that affects soil development.

a. Time c. Type of rock

b. Slope d. all of the above

The ____ horizon has smaller rock and mineral

particles than the other layers.

a. A c. C

b. B d. D

Below the C horizon is ____.

a. topsoil c. clay

b. rock d. humus

Mechanical weathering ____.

a. breaks apart rocks by physical processes

b. occurs when chemical reactions dissolve or change the minerals in


c. occurs when iron is exposed to oxygen and water

d. none of the above

Chemical weathering ____.

a. is caused by freezing and thawing

b. breaks apart rocks by physical processes

c. occurs when chemical reactions dissolve or change the minerals in rocks

d. none of above

In areas where freezing and thawing occur frequently,

rocks weather rapidly because of the ____ of freezing water.

a. evaporation c. leaching

b. expansion d. oxidation

Because desert soils contain little organic material,

their soil profiles have ____ horizons.

a. thick c. thin

b. no d. b or c

Soil erosion occurs ____.

a. where animals eat away all the plants

b. when forests are removed

c. on steep slopes

d. all of the above

The ____ in rocks are the spaces between the grains

and crystals, and also are the cracks in rocks.

a. deposits c. pores

b. saturation zones d. sediments

____ rock contains well-connected pores and allows

groundwater to flow through it.

a. Nonporous c. Impermeable

b. Low-porosity d. Permeable

The ____ is the zone where pores are full of water.

a. zone of aeration c. zone of saturation

b. zone of fractures d. water table

A well that is drilled into a pressurized aquifer is called a ___

a. sandwiched aquifer c. artesian well

b. spring d. geyser

Geologic time is divided into units based upon types of

a. sedimentary rocks c. organisms

b. climatic changes d. igneous rocks

The longest subdivision in geologic time is a(n) ____.

a. epoch c. century

b. period d. eon

____ existed during the Mesozoic Era.

a. Angiosperms c. Birds

b. Humans d. both a and c

Cenozoic Era life-forms include ____.

a. humans c. marine mammals

b. reptiles d. all of the above

Homo sapiens probably appeared ____ ago.

a. 66 million years c. 400,000 years

b. 6 million years d. none of the above

The end of the Paleozoic Era was signaled by ____.

a. the development of humans

b. mass extinction of land and sea animals

c. the development of organisms with hard parts

d. both a and b

Animal life in the Paleozoic Era included all of the

following EXCEPT ____.
a. marine life c. amphibians

b. humans d. reptiles

The division of Earth’s history into smaller units makes

up the ____.

a. eras c. periods

b. geologic time scale d. sequence of events

A stream can erode no deeper than its ____ level.

a. angular c. core

b. base d. point

____ streams have channels with many curves.

a. Meandering c. Drainage

b. Braided d. Canyon

Streams with bars, islands, and divided channels are

called ____ streams.

a. meandering c. drainage

b. braided d. canyon

The entire land area drained by a stream is called the

drainage ____.

a. point c. basin

b. bar d. fan

A ____ separates a drainage basin of one stream from

the drainage basin of another.

a. point c. erosion

b. bar d. divide

A ____ is formed by sediment deposited where a

stream empties into a gulf or a bay.

a. fan c. braid

b. delta d. floodplain

true or false: Radiocarbon dating would be useful in dating the age of


true or false: Absolute age examines the position of rocks in a sequence.
t/f : Groundwater is found in pores of soil and rock.
t/f: A low volume of pores means the rock has low porosity.
t/f: As the human population continues to increase, less
groundwater will be used.
t/f: The greater the slope of the water table, the faster
the groundwater flows.
t/F: Streams with high suspended load appear clear.