One cause of mechanical weathering is _____________, or the wearing away of rock by rock particles.
abrasion
100
A marble statue is left exposed to the weather. Within a few years, the details on the statue have begun to weather away. This weathering probably is caused by ______________.
carbonic acid in rainwater
100
Which soil particle is the smallest?
clay
100
The thick mass of grass roots that helps hold prairie soil in place is called _____________
sod
100
The most important factors that determine the rate of weathering is ______________ and ____________
rock type and climate
200
The action of animals most commonly can cause the type of weathering known as __________.
mechanical
200
A rock containing iron becomes soft and crumbly and reddish-brown in color. It probably has been chemically weathered by ____________.
oxygen
200
Most of the work of mixing humus within the soil is done by __________________.
earthworms
200
Plowing removed the grass from the Great Plains and exposed the soil. What effect did this have when a drought struck the Great Plains during the 1930s?
Helped cause the Dust Bowl
200
Soil is a valuable resource because it ____________
is important to all living things on land
300
Wedges of ice in rocks widen and deepen cracks. This process is called ________________.
ice wedging
300
____________________ produces rock particles that have a different mineral makeup from the rock they came from.
chemical weathering
300
Soil formation begins with the weathering of ___________
rock
300
_________________ disturbs the soil and its plant cover as little as possible.
conservation plowing
300
A permeable rock weathers easily because it
contains many small, connected airspaces
400
_______________ weathering can eventually wear away whole mountains.
mechanical
400
______________ is the most important agent of chemical weathering.
water
400
The layer of soil in which topsoil is found is the ____________
C horizon
400
_____________________ is the practice of plowing fields along the curves of a slope.
contour plowing
400
Soil begins to form when the solid layer of rock called ____________ weathers.
bedrock
500
Mechanical weathering works _______________.
slowly
500
_______________ causes very rapid chemical weathering.
acid rain
500
The texture of soil depends on
the size of individual soil particles
500
____________________ is the management of soil to prevent its destruction.
soil conservation
500
The A horizon, or ______________, is often very dark brown due to its high humus content.