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