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Glossary
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Below you will find key words and concepts that you should remember from this chapter.
A horizon (zone of leaching)  The top layer of soil, characterized by the downward movement of water; also called zone of leaching.
(See page(s) 311)
B horizon (zone of accumulation)  A soil layer characterized by the accumulation of material leached downward from the A horizon above; also called zone of accumulation.
(See page(s) 311)
chemical weathering  The decomposition of rock resulting from exposure to water and atmospheric gases.
(See page(s) 301)
C horizon  A soil layer composed of incompletely weathered parent material.
(See page(s) 311)
clay mineral  A hydrous aluminum-silicate that occurs as a platy grain of microscopic size with a sheet silicate structure.
(See page(s) 308)
differential weathering  Varying rates of weathering resulting from some rocks in an area being more resistant to weathering than others.
(See page(s) 303)
erosion  The physical removal of rock by an agent such as running water, glacial ice, or wind.
(See page(s) 300)
exfoliation  The stripping of concentric rock slabs from the outer surface of a rock mass.
(See page(s) 304)
exfoliation dome  A large, rounded landform developed in a massive rock, such as granite, by the process of exfoliation.
(See page(s) 304)
frost action  Mechanical weathering of rock by freezing water.
(See page(s) 303)
frost heaving  The lifting of rock or soil by the expansion of freezing water.
(See page(s) 303)
frost wedging  A type of frost action in which the expansion of freezing water pries a rock apart.
(See page(s) 303)
hematite  A type of iron oxide that has a brick-red color when powdered; Fe2O3.
(See page(s) 306)
laterite  Highly leached soil that forms in regions of tropical climate with high temperatures and very abundant rainfall.
(See page(s) 315)
limonite  A type of iron oxide that is yellowish-brown when powdered; Fe2O3·nH2O.
(See page(s) 306)
loam  Soil containing approximately equal amounts of sand, silt, and clay.
(See page(s) 311)
mechanical weathering  The physical disintegration of rock into smaller pieces.
(See page(s) 301)
O horizon  Dark-colored soil layer that is rich in organic material and forms just below surface vegetation.
(See page(s) 311)
pressure release  A significant type of mechanical weathering that causes rocks to crack when overburden is removed.
(See page(s) 303)
residual soil  Soil that develops directly from weathering of the rock below.
(See page(s) 312)
sheet joints  Cracks that develop parallel to the outer surface of a large mass of expanding rock, as pressure is released during unloading.
(See page(s) 303)
soil  A layer of weathered, unconsolidated material on top of bedrock; often also defined as containing organic matter and being capable of supporting plant growth.
(See page(s) 310)
soil horizon  Any of the layers of soil that are distinguishable by characteristic physical or chemical properties.
(See page(s) 311)
spheroidally weathered boulder  Rounded by weathering from an initial blocky shape.
(See page(s) 301)
transportation  The movement of eroded particles by agents such as rivers, waves, glaciers, or wind.
(See page(s) 300)
transported soil  Soil not formed from the local rock but from parent material brought in from some other region and deposited, usually by running water, wind, or glacial ice.
(See page(s) 312)
weathering  The group of processes that change rock at or near Earth’s surface.
(See page(s) 300)
E horizon  soil zone where downward movement of water removes fine-grained soil components such as clay.
(See page(s) 311)







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