Weathering, Erosion and Soils

An important weathering product of the hydrolysis of orthoclase is ____.

Clay minerals

In a soil profile, horizon A is called the zone of accumulation.

False

Thermal expansion and contraction occur because rock is an excellent conductor of heat.

False

In the Northern Hemisphere, north-facing slopes ____.

Receive less sunlight than south facing slopes

The difference in elevation between high and low points in a region is called ____.

Relief

Frost wedging in the mountains produces ____.

Talus

Salinization occurs when the concentration of salts increases in a soil, making it unfit for agriculture.

True

Salt crystals can exert enough force to widen cracks and dislodge particles in some rocks.

True

Horizon A in a soil is ____.

composed mostly of clays and stable minerals

Water molecules ____.

have an symmetric shape

An overall average rate of soil formation might be about ____ per century.

2.5 cm

Frost action involving water repeatedly freezing and thawing in cracks and pores in rocks is a type of chemical weathering.

False

Observed in a vertical cross section, soil is made up of distinct layers. From the surface downward, the layers are designated ____.

O, A, E, B, and C

Bauxite, which is formed during chemical weathering, is known as a residual concentration.

True

If an area is underlain by limestone soils, acid rain tends to be neutralized.

True

Laterite soils are typical of rainforests.

True

Mass wasting is a gravity-driven process.

True

When solution takes place, the ions of a substance separate in a liquid, and the solid substance dissolves.

True

Weathering is classified as either mechanical or ____.

chemical

During spheroidal weathering of a rectangular stone, the ___.

corners are attacked by weathering from three sides

A unique physical property of water is that it ____.

expands when it freezes

Soil develops ____.

faster on unconsolidated sediment than it does on bedrock

Hydrolysis is particularly effective in weathering ____.

feldspar

Frost action is most effective ____

in high mountains

Humus ____.

is the dark, organic-rich material formed by bacterial decay

Caliche is a ____.

layer of precipitated calcium carbonate in horizon B

Erosion is ____.

made worse by plowing, overgrazing, and deforestation

Salinization of soils ____.

makes them unfit for agriculture

A measure of hydrogen ion concentration is known as ____.

pH

Organisms contribute to chemical weathering by ____.

removing ions from soil water

Clay particles in soil are important in soil development because they ____.

retain water and supply nutrients

Pressure release occurs when ____.

rocks are uplifted and eroded

A type of mechanical weathering is ____ and a type of chemical weathering is ____.

salt crystal growth; hydrolysis

Rills are ____.

shallow enough to be eliminated by plowing

Pressure release weathering results in ____.

sheet joints

Some types of bacteria are extremely important in changing atmospheric nitrogen into a form of ____.

soil nitrogen suitable for use by plants

When a rock is broken into smaller pieces, its ____.

surface area increases but its volume remains the same

Erosion is the ____.

the movement of weathered material from its source site

Carbonic acid forms from a combination of ____.

water and carbon dioxide

Horizon B has fewer organisms and less organic matter than horizon A. This horizon is also called the ____.

zone of accumulation