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Porosity
a measure of how much of a rock is open space.
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Confined aquifer
an aquifer in which an impermeable dirt/rock layer exists that prevents water from seeping into the aquifer from the ground surface located directly above.
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Unconfined aquifers
those into which water seeps from the ground surface directly above the aquifer
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Aquitard
A water-saturated sediment or rock whose permeability is so low it cannot transmit any useful amount of water.
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Artesian well
a well in which water is under pressure
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Cone of depression
occurs in an aquifer when groundwater is pumped from a well.
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Subsidence
the gradual caving in or sinking of an area of land.
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Karst topography
a landscape formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum; characterized by underground drainage systems with sinkholes, dolines, and caves.
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Cryosphere
the frozen water part of the Earth system.
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Glaciers
a slowly moving mass or river of ice formed by the accumulation and compaction of snow on mountains or near the poles.
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Zone of accumulation
the part of a glacier's surface, usually at higher elevations, on which there is net accumulation of snow, which subsequently turns into firn and then glacier ice.
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Zone of ablation
the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass due to melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, avalanche, and any other ablation.
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Plucking
a glacial phenomenon that is responsible for the erosion and transportation of bedrock, especially large "joint blocks".
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Abrasion
the mechanical scraping of a rock surface by friction between rocks and moving particles during their transport by wind, glacier, waves, gravity, running water or erosion.
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Crevasse
a deep crack, or fracture, found in an ice sheet or glacier, as opposed to a crevice that forms in rock.
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Transverse crevasse
a crevasse that commonly opens across a glacier where the slope of its floor abruptly steepens.
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Longitudinal crevasse
a crevasse roughly parallel to the direction of ice movement that forms where a glacier spreads laterally.
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Terminal moraine
a moraine deposited at the point of furthest advance of a glacier or ice sheet.
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Alluvium
a deposit of clay, silt, sand, and gravel left by flowing streams in a river valley or delta, typically producing fertile soil.
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Drift
all material of glacial origin found anywhere on land or at sea, including sediment and large rocks
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Till
unsorted material deposited directly by glacial ice and showing no stratification.
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Albedo
the fraction of solar energy (shortwave radiation) reflected from the Earth back into space.
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Delta
a landform that forms at the mouth of a river, where the river flows into an ocean, sea, estuary, lake, or reservoir.
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Meander
a bend in a sinuous watercourse or river. A meander forms when moving water in a stream erodes the outer banks and widens its valley, and the inner part of the river has less energy and deposits silt.
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