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weathering
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The set of all processes that decay and break up bedrock, by a combination of physically fracturing or chemical decomposition.
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weathering
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Weathering includes two surface or near-surface processes that work in concert to decompose rocks. Both processes occur in place. No movement is involved in weathering. Chemical weathering involves a chemical change in at least some of the mineral within a rock. Mechanical weathering involves physically breaking rocks into fragments without changing the chemical make-up of the minerals within it. Mechanical weathering includes processes such as water in cracks freezing and expanding, or changes in temperature that expand and shrink individual minerals enough to break them apart.
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weathering (surface)
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Weathering includes the processes which mechanically and chemically wear and fragment rock.
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erosion
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The set of all processes by which soil and rock are loosened and moved downhill or downwind.
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saprolite
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Fine-grained weathering zone with microscopic or submicroscopic porosity occurring immediately above parent material bedrock. Saprolite is not contaminated by invasion of detritus from above and may or may not be isovolumetric.
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exfoliation
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A physical weathering process in which sheets of rock are fractured and detached from an outcrop.
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abrasion
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The wearing away of a rock by friction, rubbing, scraping, or grinding of a river's, glacier's, or wind's load.
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chemical weathering
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The total set of all chemical reactions that act on rock exposed to water and atmosphere and so change it mineral to stable form.
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dissolution
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The process of chemical weathering of bedrock in which the combination of water and acid slowly removes mineral compounds from solid bedrock and carries them away in liquid solution. Also called chemical solution.
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carbonic acid
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A mild acid formed when water and carbon dioxide chemically combine in the atmosphere and soil.This acid is a very important component in the development of cave decorations (speleothems)
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reverse weathering
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Collection of processes that lead to return of protons consumed in the process of chemical weathering to earth's surface system.
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oxidation
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A chemical reaction in which electron are lost from an atom and its charge becomes more positive.
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mechanical weathering
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The set of all physical processes by which an outcrop is broken up into small particles.
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differential weathering
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The process where some rocks are worn away less rapidly than others causing them to stand out in greater relief than the softer rocks in an exposure.
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differential erosion
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see differential weathering
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joint
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A large and relatively planar fracture in a rock across which there is no relative displacement of the two sides.
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fissures
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Elongated fracture or cracks on the slope of a volcano. Fissure eruption typically produce liquid flows,but pyroclastic may also be ejected.
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sinkhole
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A depression in the surface commonly found in in karst landscapes. Sinkholes often form where limestone or some other soluble rock is partially dissolved by groundwater, then collapses to form a depression. Sinkholes are often bowl-shaped and can be a few to many hundreds of meters in diameter. Also known as dolines.
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speleothem
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A deposit formed in cave when calcium carbonate (CaCO3) or some other mineral precipitates from drips or thin films of water. Stalactites and stalagmite are common speleothem.
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stalactite
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A mineral deposit (speleothem) which hangs downwards from a roof or wall of a cave. See stalagmite.
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stalagmite
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A mineral deposit (speleothem) which projects upwards from a cave floor. See stalactite.
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talus
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Pile of rock rubble below a cliff or chute. Talus slope is a common usage although it is redundant because the term talus actually includes the concept of a slope.
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angle of repose
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The steepest slope angle in which a particular sediment will lie without cascading down.
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rock glacier
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A glacier-like mass of rock fragments or talus with interstitial ice that moves downhill under the force of gravity.
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transportation
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The movement of sediment and rocks from one location to another by water, ice, wind or gravity.
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mass wasting
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Movement of rock and soil downslope under the influence of gravity.
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grus
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Coarse sand and gravel that form from weathering of granitic rocks
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precarious boulder
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A large rock resting on another in an unstable position. Precarious boulder may remain in place for thousands of years until an earthquake or human-caused tremor dislodges them.
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liquefaction
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The process in which a solid (soil) takes on the characteristics of a liquid as a result of an increase in pore pressure and a reduction in stress.
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hoodoo
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A column or pillar of rock of varying hardness. Its unique shape is the result of differential erosion.
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