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Geography Chapter 13
Term | Definition |
---|---|
Denudation | A term that refers to all processes that cause degradation of the landscape: weathering, mass movement, erosion, and transport |
Slope | A curved, inclined surface that bounds a landform |
Weathering | The process by which surface and subsurface rock disintegrate, dissolve, or are broken down |
Differential Weathering | The effect of different resistances in rock, coupled with variations in the intensity of physical and chemical weathering |
Regolith | Partially weathered rock overlaying bedrock |
Parent Material | The unconsolidated material, from both organic and mineral sources, that is the basis of soil development |
Physical Weathering | The breaking up and disintegrating of rock without any chemical alteration; sometimes referred to as mechanical or fragmentation weathering |
Chemical Weathering | Decomposition and decay of the constituent minerals in rock through chemical alteration of those minerals |
Frost Wedging | The physical weathering process driven by frost action, or freeze-thaw action, that breaks rocks apart |
Pressure-Release / Exfoliation | The process whereby rock peels or slips off in sheets. Occurs as a result of pressure from below being released by the removal of overlaying rock |
Thermal Expansion | Occurs as rock surfaces heated by the Sun during the day expand slightly, and then contract with nighttime cooling |
Salt-Crystal Growth (Salt Weathering) | Especially in arid climates where heating is intense, evaporation draws moisture to the surface of rocks, leaving behind previously dissolved minerals, especially salts, in the form of crystals |
Joint | Fractions or separations in rock that occur without displacement of the rock on either side |
Sheeting | The process whereby rock peels or slips off in sheets |
Hydrolysis / Hydration | Water combines with a mineral, becoming a part of its chemical composition and forming a hydrate |
Oxidation | Metallic elements in a mineral combine with oxygen to form oxides |
Carbonation | A chemical weathering process in which weak carbonic acid reacts with minerals (especially limestone), transforming them into carbonates |
Karst Topography | Landscapes formed by chemical weathering (typically of limestone) involving dissolution of carbonates. Characterized by pitted, bumpy surface topography and solution channels underground |
Sinkhole | Nearly circular depression created by the weathering of Karst landscapes with subterranean drainage |
Cones / Cockpits / Towers | Cockpit karst forms after cave systems have collapsed, forming large valleys and hills. Cone karst has limestone hills and cones, typically covered by rain forest. Tower karst has large pillars of limestone with very steep sides |
Caves / Caverns | Caves are natural underground areas large enough for humans to enter. They often form in limestone, which is easily dissolved by carbonation. Caverns are large caves formed by chemical processes |
Mass Movement / Mass Wasting | The downslope movement of a body of material made up of soil, sediment, or rock propelled by the force of gravity |
Rockfall | Free-falling movement of debris from a cliff or a steep slop, generally falling straight or bounding downslope |
Slides | A type of mass movement in which material moves as a unit along a zone of weakness that separates the material from stable, underlying material. Intermediate in both movement and water content |
Talus Slope | Cone-shaped piles of broken rocks at the base of a steep incline. Formed by rockfall |
Debris Flow | A type of mass movement that flows downslope in a slurry of unconsolidated material |
Mud Flow | A faster, more fluid flow of water and materials finer than sand |
Debris Avalanche | A high-speed flow of rock and debris, sometimes fluidized by ice in steep mountain regions |
Soil Creep | A persistent mass movement of surface soil where individual soil particles are lifted and disturbed by the expansion of soil moisture as it freezes or by grazing livestock or digging animals |
Human-Induced Mass Movement | The movement of soil, sediment, and rock material caused by human activity |