Earth Science Final Meredith College
Erosion
Removal of weathered rocks. Occurs when rain, running water, wind, glaciers, or gravity transport material somewhere else
Mechanic weathering
Physical-the disintegration of rock into smaller pieces by physical processes without altering the chemical composition of the rock
Chemical weathering
The decomposition of rock when it comes in contact with AIR, WATER, or other agent in the environment. Alters chemical composition and mineral content
Pressure-release fracturing
Mechanical weathering process when tectonic forces lift deeply buried rocks close to the surface and erode overlying sediment. This expands the rock and fractures them
Frost wedging
Mechanical weathering process in which water freezes in a crack in rock, then the expansion wedges apart the rock
Talus
Accumulation of loose, angular rocks at the base of a cliff. Created when rocks broke off as a result of frost wedging
Abrasion
Mechanical weathering process that consists of the grinding and ROUNDING of rock surfaces by friction and impact
Organic activity
Mechanical weathering process in which a crack in a rock is expanded by TREE or plant roots growing
Thermal expansion and contraction
Mechanical weathering process that fractures rocks when temperature changes rapidly, causing the surface of the rock to heat or cool faster than the interior. This expands or contracts it causing it to weather
Dissolution
Chemical weathering process in which mineral or rocks dissolves, forming a solution
True or false: Rocks and minerals dissolve more rapidly when water is either acidic or basic
True
Litter
Leaves, twigs, and other plant or animals material that have fallen to the surface of the soil but have not decomposed
Hydrolysis
Chemical weathering process in which a mineral reacts with water to forma new mineral that has water as part of its chemical structure
Oxidation
A chemical weathering process in which salts that are dissolved in water in the pores of rock crystallize, widening cracks and pushing the mineral grains apart
Salt cracking
A chemical weathering process in which salts that are dissolved in water in the pores or rock crystallize, widening cracks, and pushing the mineral grains apart
Exfoliation
Weathering process resulting in fracture when concentric plates or shells split away from a main rock mass like the layers of an onion
Regolith
Thin layer of loose, unconsolidated weathered material that overlies bedrock (soil)
Soil
The upper layers of regolith that support plant growth
Loam
The most fertile soil, a mixture especially rich in sand and silt with generous amounts of organic matter
Explain the role of the four spheres in soil formation process
Geosphere-weathered rock turns to regolith
Hydrosphere-infiltration
Atmosphere-aeration (soil needs oxygen, nitrogen, and COs for plants)
Biosphere-source of organic matter
Humus
Dark, organic component of soil consisting of litter that has decomposed enough so that the origin of the individual species cannot be determined
Soil horizon
A layer of soil that is distinguishable from other layers because of differences in appearance in physical and chemical properties
O horizon
Uppermost layer of soil, named for it organic component; the combined O and A horizons are called topsoil
A horizon
the layer of soil below the O horizon, composed of a mixture of humus, sand, silt, and clay
B horizon
The soil layer below the A horizon, contains less organic matter, and where ions leached from the A horizon accumulate. Also called SUBSOIL
C horizon
the lowest soil layer
Leaching
the downward movement of water and dissolved ions from the O and A soil horizons, into the B horizon, where they accumulate
Capillary action
The process by which water is pulled upward thorugh the soil due to natural attraction of water molecules to soil particles
Pedocal
Salt encrusted soil in arid and semiarid climates characterized by an accumulation of calcium carbonate
Caliche
hard crust on the soil of arid or semiarid regions formed when calcium carbonate precipitates and cements the soil particles together
Slump
Subcategory of slide mass wasting in which blocks of material slide downslope as a consolidated unit over a fracture in rock or regolith; trees on the slumping blocks tilt uphill
Rockslide
Subcategory of slide mass wasting in which a segment of bedrock slides downslope along a fracture and the rock breaks into fragments and tumbles down the hillside; also a called a rock avalanche
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