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Geog Vocab
Geog Final
Term | Definition |
---|---|
Core | The deeper inner portion of Earth, representing one-third of its entire of its third mass; differentiated into two zones—a solid iron inner core surrounded by a dense, molten, fluid metallic iron outer core |
Mantle | An area within the planet representing about 80% of Earth’s total volume, with densities increasing with depth; occurs above the core and below the crust, rich in iron and magnesium oxides and silicates |
Crust | Earth’s outer shell of crystalline surface rock, ranging from 5 to 60 km in thickness from oceanic crust to mountain ranges |
Geologic Cycle | A general term characterizing the vast cycling in and on the lithosphere; It encompasses the hydrologic cycle, tectonic cycle, and rock cycle |
Mineral | An element or combination of elements that form an inorganic natural compound; described by a specific formula and qualities of specific names |
Rock | An assemblage of minerals bound together or a mass of a single mineral |
Igneous Rock | One of the basic rock types; it has solidified and crystallized from a hot molten state |
Sedimentary Rock | Formed from the compaction, cementation, and hardening of sediments derived from former rocks |
Limestone | The most common chemical sedimentary rock; lithified calcium carbonate, which is very susceptible to chemical weathering by acids in the environment, including carbonic acid in rainfall |
Metamorphic Rock | Existing rock, both igneous and sedimentary, that goes through profound physical and chemical changes under increased pressure and temperature. Constituent mineral structures may exhibit foliated or nonfoiliated textures |
Pangea | The super-continent formed by the collision of all continental masses approximately 225 million years ago; named by Wegner and his continental drift theory. |
Plate Tectonics | The conceptual model that encompasses continental drift, sea-floor spreading, and related aspects of crustal movement; accepted as the foundation of crustal tectonic processes |
Sea-floor Spreading | Proposed by Hess and Dietz The mechanism driving the movement of the continents, associated with upwelling flows of magma along the worldwide system of mid-ocean ridges |
Relief | The elevation differences in a local landscape; an expression of local height differences of landforms |
Topography | The undulations and configurations that give Earth’s surface its texture; the heights and depths of local relief, including both natural and human-made features |
Folding | A process that bends and deforms beds of various rocks subjected to compressional forces |
Geomorphology | The science that analyzes and describes the origin, evolution, form, classification, and spatial distribution of landforms |
Differential Weathering | The effect of different resistance in rock, coupled with variations in the intensity of physical and chemical weathering |
Slope | A curved, inclined surface that bounds a landform |
Weathering | The related processes by which surface and subsurface rock disintegrate, or dissolve, or are otherwise broken down. Rocks at or near Earth’s surface are exposed to physical, organic, and chemical weathering processes |
Regolith | The partially weathered rock overlying bedrock, whether residual or transported |
Bedrock | The rock of Earth’s crust that is below the social and basically unweathered; solid crust sometimes is exposed as an outcrop |
Sediment | The fine-grained mineral matter that is transported and deposited by air, water, or ice |
Parental Material | The unconsolidated material, from both organic and mineral sources, that is the basis of soil development |
Joints | A fracture or separation in rock without displacement of the sides; it increases the surface area of rock exposed to weathering processes |
Physical Weathering | The breaking and disintegrating of rock without any chemical alteration; sometimes referred to as mechanical or fragmentation weathering |
Frost Action | A powerful mechanical force produced as water volume expands 9% as it freezes; can exceed the tensional strength of rock, breaking it |
Sheeting | A form of weathering associated with fracturing or fragmentation of rock by pressure release; often related to exfoliation processes |
Exfoliation | A dome-shaped feature of weathering produced by the response of granite to the overburden removal process, which relieves pressure from the rock. Layers of rock slough off in slabs or shells in a sheeting process |
Chemical Weathering | The decomposition and decay of the constituent minerals in rock through chemical alteration of those minerals. Water is essential, with rates keyed to temp and precip values. Chemical reactions are active at microsites even in dry climates |
Oxidation | A chemical weathering process whereby oxygen oxidizes certain metallic elements to form oxides most familiar as the "rusting" of iron in a rock or soil that produces a reddish-brown stain of iron oxide |
Carbonation | A process of chemical weathering by a weak carbonic acid that reacts with many minerals containing calcium, magnesium, potassium, and sodium transforming them into carbonates |
Karst Topography | A distinctive topography formed in a region of chemically weathered limestone with poorly developed surface drainage and solution features that appear pitted and bumpy |
Sinkholes | A nearly circular depression, also known as a doline. created by the weathering of karst landscapes; may collapse through the roof of an underground space |
Mass Movement/Mass Wasting | All unit measurements of materials propelled by gravity; can range from dry to wet, slow to fast, small to large, and free-falling to gradual or intermittent |
Rockfall | A free-falling movement of debris from a cliff or steep slope, generally falling straight down or bounding downslope |
Landslide | A sudden, rapid, downslope movement of a cohesive mass of regolith and/or bedrock in a variety of mass-movement forms under the influence of gravity |
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 even by grazing livestock or digging animals |
Hydrology | The science of water and its global circulation, distribution, and properties |
Fluvial | Stream-related processes |
Erosion | Denudation by wind, water, and ice, which dislodges, dissolves, or removes surface material |
Deposition | The process whereby weathered, wasted, and transported sediments, deposited by air, water, or ice, are laid down |
Alluvium | A general descriptive term for clay, silt, and sand, transported by running water and deposited in sorted or semi-sorted sediment on a floodplain, delta, or streambed |
Drainage Basin | The basic spatial geomorphic unit of streams in a region determined by slope, differing rock resistance to weathering and erosion, climatic and hydrologic variability, and structural controls of the landscape |
Continental Divides | A ridge or elevated area that determines the drainage pattern of drainage basins; specifically, that ridge in North America that separates drainage to the Pacific in the west from drainage to the Atlantic and Gulf in the east and to the Hudson Bay |
Drainage Patterns | A geometric arrangement of streams in a region determined by slope, differing rock resistance to weathering and erosion, climatic and hydrologic variability, and structural controls of the landscape |
Discharge | The measured volume of flow in a river that passes by a given cross section of a stream in a given unit of time; expressed in cubic meters per second or cubic feet per second |
Dissolved Load | Materials carried in a stream in chemical solution derived from minerals such as limestone and dolomite or from soluble salts |
Suspended Load | The fine particles held in suspension in a stream. The finest particles are not deposited until the stream velocity nears zero |
Bed Load | Course materials that are dragged along the bed of a stream by traction or by the rolling and bouncing motion of saltation; involves particles too large to remain in suspension |
Traction | A type of sediment transport that drags coarser materials along the bed of a stream |
Saltation | The transport of sand grains by stream or wind, which bounce the grains along the ground in asymmetrical paths |
Braided Stream | A stream that becomes a maze of interconnected channels laced with excess sediments. Braiding often occurs with a reduction of discharge that affects a stream's transportation ability or an increase in sediment load |
Meandering Stream | The sinuous, curving pattern common to graded streams, with the outer portion of each curve subjected to the greatest erosive action and the inner portion receiving sediment deposits |
Oxbow Lake | A lake that was formerly part of the channel of a meandering stream, isolated when a stream eroded its outer bank, forming a cutoff through the neck of a looping meander |
Nickpoint | The point at which the longitudinal profile of a stream is abruptly broken by a change in gradient |
Floodplain | A low-lying area near a stream channel, subject to recurrent flooding; alluvial deposits generally mask underlying rock |
Natural Levee | A long, low ridge that occurs on either side of a river in a developed floodplain; depositional by-products of river-flooding episodes |
Alluvial Terraces | Level areas that appear as topographic steps above the stream; created by a stream as it scours with renewed downcutting into its floodplain; composed of unconsolidated alluvium |
Delta | A depositional plain formed where a river enters a lake or an ocean; named after the triangular shape of the Greek letter delta |
Eolian/Aeolian | Caused by wind; refers to erosion, transportation, and deposition of materials |
Deflation | A process of wind erosion that removes and lifts individual particles, literally blowing away unconsolidated, dry, or noncohesive sediments |
Abrasion | The mechanical wearing and erosion of bedrock accomplished by the rolling and grinding of particles and rocks carried in a stream, moved by wind in a "sandblasting" action, or imbedded in glacial ice |
Desert Pavement | In arid landscapes, a surface formed when wind deflation and sheet flow remove smaller particles, leaving residual pebbles and gravels to concentrate at the surface; resembles a cobblestone street |
Surface Creep | A form of eolian transport that involves particles too large for saltation; a process whereby individual grains are impacted by moving grains and slide and roll |
Dunes | A depositional feature of sand grains deposited in a transient mound, ridge, or hill |
Loess | Large quantities of fine-grained clays and silts left as glacial outwash deposits and subsequently blown by the wind great distances and redeposited as a generally unstratified, homogeneous blanket of material covering existing landscapes |
Desertification | The expansion of deserts worldwide, related principally to poor agricultural practices, improper soil-moisture management, erosion and salinization, deforestation, and the ongoing climatic change |
Littoral Zone | A specific coastal environment; that region between the high-water line during a storm and a depth at which storm waves are unable to move sea-floor sediments |
Mean Sea Level | The average of tidal levels recorded hourly at a given site over a long period of time, which must be at least full lunar tidal cycle |
Tides | The pattern of daily oscillations in sea level produced by astronomical relationships among the Sun, the Moon, and Earth; experienced in varying degrees around the world |
Waves | An undulation of ocean water produced by the conversion of solar energy to wave energy; produced in a generating region or a stormy area of the sea |
Longshore Current | A current that forms parallel to a beach as waves arrive at an angle to the shore, generated in the surf zone by wave action, transporting large amounts of sand and sediment |
Lagoon | A portion of coastal seawater that is virtually cut off from the ocean by a bay barrier or barrier beach |
Beach | The portion of the coastline where an accumulation of sediment is in motion |
Coral | A simple, cylindrical marine animal with a saclike body that secretes calcium carbonate to form a hard external skeleton and landforms called reefs; lives symbiotically with nutrient producing algae |
Glacier | A large mass of perennial ice resting on land or floating shelf-like in the sea adjacent to the land; formed from the accumulation and recrystallization of snow, it then flows slowly under the pressure of its own weight and the pull of gravity |
Alpine Glacier | A glacier confined in a mountain valley or walled basin, consisting of three subtypes: valley glacier, peidmont glacier, and outlet glacier |
Continental Glacier | A continuous mass of unconfined ice, covering as least 50,000 km2 |
Ice Sheet | An enormous, continuous continental glacier. The bulk of glacial ice on Earth covers Antarctica and Greenland in two ice sheets |
Ice Cap | A dome-shaped glacier, less extensive than an ice sheer, although it buries mountain peaks and the local landscape |
Ice Field | An extensive form of land ice, with mountain ridges and peaks visible above the ice; less extensive than an ice cap or ice sheet |
Firn | Snow of a granular texture that is transitional in the slow transformation of snow to glacial ice; snow that has persisted through the summer season in the zone of accumulation |
Ablation | The loss of glacial ice through melting, sublimation, wind removal by deflation, or the calving off of blocks of ice |
Abrasion | The mechanical wearing and erosion of bedrock accomplished by the rolling and grinding of particles and rocks carried in a stream, moved by wind in a "sandblasting" action, or embedded in glacial ice |
Glacial Drift | The general term for all glacial deposits, both unsorted and sorted |
Moraine | A marginal glacial deposit of unsorted and unstratified material |
Lateral Moraine | The debris transported by a glacier that accumulates along the sides of the glacier and is deposited along these margins |
Medial Moraine | The debris transported by a glacier that accumulates down the middle of the glacier when two glaciers merge and their local moraines combine; forms a depositional feature following glacial retreat |
Till Plain | A large, relatively flat plain composed of unsorted glacial deposits behind a terminal or end moraine. Low, rolling relief and unclear drainage patterns are characteristics |
Outwash Plain | The glaciofluvial deposits of stratified drift from meltwater-fed, braided, and overloaded streams; beyond a glacier's morainal deposits |
Permafrost | The permanently frozen layer that forms when soil or rock temperatures remain blow 0C for at least 2 years in areas considered periglacial; the criterion is based on temp and not on whether water is present |