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Earth Sciences
GEO 202 Oregon State University
249
Geology
02/09/2011

Additional Geology Flashcards

 


 

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Term
Climate
Definition
The consistent, long-term behavior of weather over time, including its variability; in contrast to weather, which is the condition of the atmosphere at any given place and time.
Term
Climatology
Definition
The study of the climate.
Term
Climatic Regions
Definition
An are of homogenous climate that features characteristics regional weather and air mass patterns.
Term
Classification
Definition
The process of ordering or grouping data or phenomena in related classes; results in a regular distribution of information; a taxonomy.
Term
Climograph
Definition
A graph that plots, daily, monthly, or annual temperature and precipitation values for a selected station; may also include additional weather information.
Term
Empirical Classification
Definition
A climate classification based on weather statistics or other data; used to determine general climate categories.
Term
General Circulation Model (GCM)
Definition
Complex, computer-based climate model that produces generalizations of reality and forecasts of future weather and climate conditions. Complex GCMs (three dimensional models) are in use in the United States and in other countries.
Term
GCM
Definition
General Circulation Model
Term
Genetic Classification
Definition
A climate classification that uses causative factors to determine climatic regions; for example, an analysis of the effect of interacting air masses.
Term
Paleoclimatology
Definition
The science that studies the climates, and the causes of variations in climate, of past ages, throughout historic and geological time.
Term
West Antarctic Ice Sheet
Definition
A vast grounded ice mass held back by the Ross, Ronne, and Filcher ice shelves in Antarctica, drained by several active ice streams, such as the active Pine Island Glacier.
Term
Asthenosphere
Definition
Region of the upper mantle just below the lithosphere; the least rigid portion of Earth's interior and known as the plastic layer, flowing very slowly under extreme heat and pressure.
Term
Basalt
Definition
A common extrusive igneous rock, fine-grained, comprising the bulk of the ocean-floor crust, lava flows, and volcanic forms.
Term
Batholith
Definition
The largest plutonic form exposed at the surface; an irregular intrusive mass; it invades crustal rocks, cooling slowly so that large crystals develop.
Term
Continental Drift
Definition
A proposal by Alfred Wegener in 1912 stating that Earth's landmasses have migrated over the past 225 million years from a super continent he called Pangaea to the present configuration.
Term
Core
Definition
The deepest inner portion of Earth, representing one-third of its entire mass; differentiated into two zones - a solid-iron inner core surrounded by a dense, molten, fluid metallic-iron outer core.
Term
Cryosphere
Definition
The frozen portion of Earth's waters, including ice sheets, ice caps and fields, glaciers, ice shelves, sea ice, and subsurface ground ice and frozen ground.
Term
Crust
Definition
Earth's outer shell of crystalline surface rock, ranging from 5 to 60 km (3 to 38 mi) in thickness from oceanic crust to mountain ranges. Average density of continental crust is 2.7 g/cm3, whereas oceanic crust is 3.0 g/cm3.
Term
Endogenic System
Definition
The system internal to Earth, driven by radioactive heat derived from sources within the planet. In response, the surface features, mountain building occurs, and earth quakes and volcanoes are activated.
Term
Exogenic System
Definition
Earth's external surface system, powered by insolation, which energizes air, water, and ice and sets them in motion, under the influence of gravity.
Term
Geologic Cycle
Definition
A general term characterizing the vast cycling that proceeds in the lithosphere. It encompasses the hydrologic cycle, tectonic cycle, and rock cycle.
Term
Geologic Time Scale
Definition
A depiction of eras, periods, and epochs that span Earth's history; shows both the sequence of rock stat and their absolute dates, as determined by methods such as radioactive isotopic dating.
Term
Geomagnetic Reversal
Definition
A polarity change in Earth's magnetic field. With uneven regularity, the magnetic field fades to zero, then returns to full strength but with the magnetic poles reversed. Reversals have been recorded 9 times during the past 4 million years.
Term
Geothermal Energy
Definition
The energy in steam and hot water heated by subsurface magma near groundwater. Geothermal energy literally refers to heat from Earth's interior, whereas geothermal power relates to specific applied strategies of geothermal electric or geothermal direct applications. This energy is used in Iceland, New Zealand, Italy and northern California, among other locations.
Term
Granite
Definition
A coarse-grained (slow cooling) intrusive igneous rock of 25% quartz and more than 50% potassium and sodium feldspars; characteristic of the continental crust.
Term
Hot Spot
Definition
An individual point of upwelling material originating in the asthenosphere, or deeper in the mantle, tends to remain fixed relative to migrating plates; some 100 are identified worldwide, exemplified by Yellowstone National Park, Hawaii, and Iceland.
Term
Igneous Rock
Definition
One of the basic rock types; it has solidified and crystallized form a hot molten state (either magma or lava).
Term
Isostasy
Definition
A state of equilibrium in Earth's crust formed by the interplay between portions of the lithosphere and the asthenosphere and the principle of buoyancy. The crust depressed under weight and recovers with its removal, for example, the melting of glacier ice.
Term
Lava
Definition
Magma that issues from volcanic activity onto the surface; the extrusive rock that results when magma solidifies.
Term
Limestone
Definition
The most common chemical factor that most inhibits biotic processes, either through lack or excess.
Term
Lithification
Definition
The compaction, cementation, and hardening of sediments into sedimentary rock.
Term
Magma
Definition
Molten rock from beneath Earth's surface; fluid, gaseous, under tremendous pressure, and either intruded into existing country rock or extruded onto the surface as lava.
Term
Mantle
Definition
An area within the planet representing about 80% of Earth's total volume, with densities increasing with depth and averaging 4.5g/cm3; occurs between the core and the crust; is rich in iron and magnesium oxides and silicates.
Term
Metamorphic Rock
Definition
One of three basic rock types, it is existing igneous and sedimentary rock that has undergone profound physical and chemical changes under increased pressure and temperature. Constituent mineral structures may exhibit foliated or non foliated textures.
Term
Mid-Ocean Ridge
Definition
A submarine mountain range that extends more than 65,000 km (40,000 mi) worldwide and averages more than 1000 km (600 mi) in width; centered along sea-floor spreading centers.
Term
Mineral
Definition
An element or combination of elements that forms an inorganic natural compound; described by a specific formula and crystal structure.
Term
Mohorovicic Discontinuity (Moho)
Definition
The boundary between the crust and the rest of the lithospheric upper mantle; named for the Yugoslavian seismologist Mohorovicic; a zone of sharp material and density contrasts.
Term
Pangaea
Definition
The super continent formed by the collision of all continental masses approximately 225 million years ago.
Term
Plate Tectonics
Definition
The conceptual model and theory that ecompasses continental drift, sea-floor spreading, and related aspects of crustal movement; accepted as the foundation of crustal tectonic processes.
Term
Pluton
Definition
A mass of intrusive igneous rock that has cooled slowly; forms in any size or shape. The largest partially exposed pluton is a batholith.
Term
Rock
Definition
An assemblage of minerals bound together, or sometimes a mass of a single mineral.
Term
Rock Cycle
Definition
A model representing the interrelationship among the three rock-forming processes; igneous, sedimentary, and metamorphic; shows how each can be transformed into another rock type.
Term
Sea-Floor Spreading
Definition
The mechanism driving the movement of the continents; associated with upwelling flows of magma along the worldwide system of mid-ocean ridges.
Term
Sedimentary Rock
Definition
One of three basic rock types; formed from the compaction, cementation, and hardening of sediments derived from other rocks.
Term
Stratigraphy
Definition
A science that analyzes the sequence, spacing, geophysical and geochemical properties, and spatial distribution of rock strata.
Term
Subduction Zone
Definition
An area where two plates of crust collide and the denser oceanic crust dives beneath the less dense continental plate, forming deep oceanic trenches and seismically active regions.
Term
Transform Fault
Definition
A type of geologic fault in rocks. An elongated zone along which faulting occurs between mid-ocean ridges; produces a relative horizontal motion with no new crust formed or consumed; strike-slip motion is either left or right lateral.
Term
Uniformitarianism
Definition
An assumption that physical processes active in the environment today are operating at the same pace and intensity that has characterized them throughout geologic time.
Term
Aa
Definition
Basaltic lava with a rough, jagged, and clinkery, basaltic lava with sharp edges. This texture is because the lava lost trapped gases, flowing slowly, developing a thick skin that cracks into the jagged surface.
Term
Angle of Repose
Definition
The steepness of a slope that results when loose particles come to rest; an angle of balance between driving and resisting forces, ranging between 33 degrees and 37 degrees from a horizontal plane.
Term
Anticline
Definition
Upfolded rock strata, in which layers slope downward from the axis of the fold, or central ridge.
Term
Bedrock
Definition
The rock of Earth's crust that is below the soil and is basically unweathered; such solid crust sometimes is exposed as an outcrop.
Term
Caldera
Definition
An interior sunken portion of a composite volcano's crater; usually steep sided and circular, sometimes containing a lake; also can be found in conjunction with shield volcanoes.
Term
Carbonation
Definition
A chemical weathering process in which weak carbonic acid (water and carbon dioxide) reacts with many minerals that contain calcium, magnesium, potassium, and sodium (especially limestone), transforming them into carbonates.
Term
Chemical Weathering
Definition
Decomposition and decay of the constituent minerals in rock through chemical alteration of those minerals. Water is essential, with rates keyed to temperature and precipitation values. Chemical reactions are active at microsites even in dry climates. Processes include hydrolysis, oxidation, carbonation and solution.
Term
Cinder Cone
Definition
A volcanic landform of pyroclastics and scoria, usually small and cone-shaped and generally not more than 450 m (1500 ft) in height, with a truncated top.
Term
Circum-Pacific Belt
Definition
A tectonically and volcanically active region encircling the Pacific Ocean; also known as the Ring of Fire.
Term
Composite Volcano
Definition
A volcano formed by a sequence of explosive volcanic eruptions; steep-sided, conical in shape; sometimes referred to as a stratovolcano, although composite is the proffered term.
Term
Continental Landmasses
Definition
The broadest category of landform, including those masses of crust that reside above or near sea level and the adjoining undersea continental shelves along the coastline; sometimes synonymous with continental platforms.
Term
Crater
Definition
A circular surface depression formed by volcanism; built by accumulation, collapse, or explosion; usually located at a volcanic vent or pipe; can be at the summit or on the flank of a volcano.
Term
Debris Avalanche
Definition
A mass of falling and tumbling rock, debris, and soil; can be dangerous because of the tremendous velocities achieved by the onrushing materials.
Term
Denudation
Definition
A general term that refers to all processes that cause the degradation of the landscape; weathering, mass movement, erosion and transport.
Term
Differential Weathering
Definition
The effect of different resistances in rock, coupled with variations in the intensity of physical and chemical weathering.
Term
Dynamic Equilibrium Model
Definition
The balancing act between tectonic uplift and erosion, between the resistance or crust materials and the work of denudation processes. Landscapes evidence ongoing adaptation to rock structure, climate, local relief, and elevation.
Term
Earthquake
Definition
A sharp release of energy that sends waves traveling through Earth's crust at the moment of rupture along a fault or in association with volcanic activity. The moment magnitude scale (formerly the Richter scale) estimates Earthquake magnitude; intensity is described by the Mercalli scale.
Term
Effusive Eruption
Definition
A volcanic eruption characterized by low-viscosity basaltic magma and low-gas content, which really escapes. Lava pours forth onto the surface with relatively small explosions and few pyroclastics; tends to form shield volcanoes.
Term
Elastic Rebound Theory
Definition
A concept describing the faulting process in Earth's crust, in which the two sides of a fault appear locked despite the motion of adjoining pieces of crust, but with accumulating strain they rupture suddenly, snapping to new positions relative to each other, generating an earthquake.
Term
Exfoliation Dome
Definition
A dome-shaped feature of weathering, produced by the response of granite to the overburden removal process, which relieves pressure form the rock. Layers of rock slough (sluff) off in slabs or shells in a sheeting process.
Term
Explosive Eruption
Definition
A violent and unpredictable volcanic eruption, the result of magma that is thicker (more viscous), stickier, and higher in gas and silica content than that of an effusive eruption; tends to form blockages within a volcano; produces composite volcanic landforms.
Term
Faulting
Definition
The process whereby displacement and fracturing occur between two portions of Earth's crust; usually associated with earthquake activity.
Term
Folding
Definition
The bending and deformation of beds of rock strata subjected to compressional forces.
Term
Frost Action
Definition
A powerful mechanical force produced as water expands up to 9% of its volume as it freezes. Water freezing in a cavity in a rock can break the rock if it exceeds the rock's tensional strength.
Term
Geomorphic Threshold
Definition
The threshold up to which landforms changed before lurching to a new set of relationships, with rapid realignments of landscape materials and slopes.
Term
Geomorphology
Definition
The science that analyses and describes the origin, evolution, form, classification, and spatial distribution of landforms.
Term
Graben
Definition
Pairs or groups of faults that produce downward-faulted blocks; characteristic of the basins of the interior western United States.
Term
Horst
Definition
Upward-faulted blocks produced by pairs or groups of faults; characteristic of the mountain ranges of the interior of the western United States.
Term
Hydration
Definition
A chemical weathering process involving water that is added to a mineral, which initiates swelling and stress withing the rock, mechanically forcing grains apart as the constituents expand.
Term
Hydrolysis
Definition
A chemical weathering process in which minerals chemically combine with water; a decomposition process that causes silicate minerals in rocks to break down and become altered.
Term
Joint
Definition
A fracture or separation in rock that occurs without displacement of the sides; increases the surface area of rock exposed to weathering processes.
Term
Karst Topography
Definition
Distinctive topography formed in a region of chemically weathered limestone with poorly developed surface drainage and solution features that appear pitted and bumpy.
Term
Landslide
Definition
A sudden rapid downslope movement of a cohesive mass or regolith and/or bedrock in a variety of mass-movement forms under the influence of gravity; a from of mass-movement.
Term
Mass Movement
Definition
All unit movements of materials propelled by gravity; can range from dry to wet, slow to fast, small to large, and free-falling to gradual or intermittent.
Term
Mass Wasting
Definition
Gravitational movement of non unified material downslope; a specific form of mass movement.
Term
Moment Magnitude Scale
Definition
An earthquake magnitude scale. Considers the amount of fault slippage, the size of the area that ruptured, and the nature of the materials that faulted in estimating the magnitude of an earthquake - an assessment of the seismic moment. Replaces the Richter scale (amplitude magnitude); especially valuable in assessing larger magnitude events.
Term
Mudflow
Definition
Fluid downslope flows of material containing more water than earthflows.
Term
Normal Fault
Definition
A type of geologic fault in rocks. Tension produces strain that breaks a rock, with one side moving vertically relative to the other side along an inclined fault place.
Term
Ocean Basin
Definition
The physical container (a depression in the lithosphere) holding an ocean.
Term
Orogenesis
Definition
The process of mountain building that occurs when large scale compression leads to deformation and uplift of the crust; literally, the birth of mountains.
Term
Oxidation
Definition
A chemical weathering process in which oxygen dissolved in water oxidizes (combines with) certain metallic elements to form oxides; most familiar is the rusting of iron in a rock or soil, which produces a reddish brown stain of iron oxide.
Term
Pahoehoe
Definition
Basaltic lava that is more fluid than aa. Pahoehoe forms a thin crust that forms folds and appears ropy, like coiled twisted rope.
Term
Parent Material
Definition
The unconsolidated material, from both organic and mineral sources, that is the basis of soil development.
Term
Physical Weathering
Definition
The breaking and disintegrating of rock without any chemical alteration; sometimes referred to as mechanical or fragmentation weathering.
Term
Plateau Basalt
Definition
An accumulation of horizontal flows formed when lava spreads out from elongated fissures onto the surface in extensive sheets; associated with effusive eruptions; also known as flood basalts.
Term
Pyroclastic
Definition
An explosively ejected rock fragment launched by a volcanic eruption; sometimes described by the more general term tephra.
Term
Regolith
Definition
Partially weathered rock overlying bedrock, whether residual or transported.
Term
Relief
Definition
Elevation differences in a lock landscape; an expression of local height difference of landforms.
Term
Reverse Fault
Definition
Compressional forces produce strain that breaks a rock so that one side moves upward relative to the other side; also called a thrust fault.
Term
Richter Scale
Definition
An open ended, logarithmic scale that estimates earthquakes magnitude now replaced by the moment magnitude scale.
Term
Ring of Fire
Definition
A tectonically and volcanically active region encircling the Pacific Ocean.
Term
Rockfall
Definition
Free-falling movement of debris from a cliff or steep slope, generally falling straight of bounding downslope.
Term
Scarification
Definition
Human-induced mass movements of Earth materials, such as large scale open pit mining and strip mining.
Term
Sediment
Definition
Fine-grained mineral matter that is transported and deposited by air, water or ice.
Term
Seismograph
Definition
A device that measures seismic waves of energy transmitted throughout Earth's interior or along the coast.
Term
Sheeting
Definition
A form of weathering associated with fracturing or fragmentation of rock by pressure release; often related to exfoliation processes.
Term
Shield Volcano
Definition
A symmetrical mountain landform built from effusive eruptions (low viscosity magma); gently sloped, gradually rising from the surrounding landscape to a summit crater; typical of the Hawaiian Islands.
Term
Sinkhole
Definition
Nearly circular depression created by the weathering of karst landscapes with subterranean drainage; also known as a doline in traditional studies; may collapse through the roof of an underground space.
Term
Slope
Definition
A curved. inclined surface that bounds a landforms.
Term
Soil Creep
Definition
A persistent mass movement of surface soil where individual soil particles are lifted and distributed by the expansion of soil moisture as it freezes or by grazing livestock or digging animals.
Term
Strike-Slip Fault
Definition
Horizontal movement along a faultline, that is, movement in the same direction as the fault; also known as a transcurrent fault. Such movement is described as right lateral or left lateral, depending on the relative motion observed across the fault.
Term
Syncline
Definition
A trough in folded strata, with beds that slope toward the axis of the downfold.
Term
Talus Slope
Definition
Formed by angular rock fragments that cascade down a slope along the base of a mountain; poorly sorted, cone-shaped deposits.
Term
Terrane
Definition
A migrating piece of Earth's crust, dragged about by processes of mantle convection and plate tectonics. Displaced terranes are distinct in their history, composition, and structure from the continents that accept them.
Term
Thrust Fault
Definition
A reverse fault where the fault plane forms a low angle relative to the horizontal; an overlying block moves over an underlying block.
Term
Topography
Definition
The undulations and configurations, including its relief, that give Earth's surface its texture; portrayed on topographic maps.
Term
Volcano
Definition
A mountainous landform at the end of a magma conduit, which rises from below the crust and vents to the surface. Magma rises and collects in a magma chamber deep below, erupting effusively or explosively and forming composite, shield, or cinder-cone volcanoes.
Term
Weathering
Definition
The processes by which surface and subsurface rocks disintegrate, or dissolve, or are broken down. Rocks at or near Earth's surface are exposed to physical and chemical weathering processes.
Term
Wrangellia Terrane
Definition
One of many terranes that became cemented together to form present-day North America and the Wrangell Mountains, arriving from approximately 10,000 km (6200 mi) away; a former volcanic island arc and associated marine sediments.
Term
Abrasion
Definition
Mechanical wearing and erosion of bedrock accomplished by the rolling and grinding of particles and rocks carried in a stream, removed by wind in a 'sandblasting' action, or imbedded in glacial ice.
Term
Aggradation
Definition
The general building of land surface because of deposition of material; opposite of degradation. When the sediment load of a stream exceeds the stream's capacity to carry it, the stream channel becomes filled through this process.
Term
Alluvial Fan
Definition
Fan-shaped fluvial landform at the month of a canyon; generally occurs in arid landscapes where streams are intermittent.
Term
Alluvial Terraces
Definition
Level areas that appear as topographic steps above a stream, created by the stream as it scours with renewed down cutting into its floodplain; composed of unconsolidated alluvium.
Term
Alluvium
Definition
General descriptive term for clay, silt, sand, gravel, or other unconsolidated rock, and mineral fragments transported by running water and deposited as sorted or semisorted sediment on a floodplain, delta, or stream bed.
Term
Backswamp
Definition
A low-lying, swampy area of a floodplain; adjacent to a river, with the river's natural levee on one side and higher topography on the other.
Term
Bajada
Definition
A continuous apron of coalesced alluvial fans, formed along the base of mountains in arid climates; presents a gently rolling surface from fan to fan.
Term
Base Level
Definition
A hypothetical level below which a stream cannot erode its valley, and thus the lowest operative level for denudation processes; in an absolute sense, it is represented by sea level, extending under the landscape.
Term
Basin and Range Province
Definition
A region of dry climates, few permanent streams, and interior drainage patterns in the western United States; a faulted landscape composed of a sequence of horsts and grabens.
Term
Bed Load
Definition
Coarse 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.
Term
Blowout Depression
Definition
Eolian (wind) erosion in which deflation forms a basin in areas of loose sediment. Diameter may range up to hundreds of meters.
Term
Bolson
Definition
The slope and basin area between the crests of two adjacent ridges in a dry region.
Term
Braided Stream
Definition
A stream that becomes a maze of interconnected channels laced with excess sediment. Braiding often occurs with a reduction of discharge that reduces a stream's transporting ability or with an increase in sediment load.
Term
Continental Divide
Definition
A ridge or elevated area that separates drainage on a continental scale; specifically, that ridge in North America that separates drainage into the Pacific on the west side from drainage to the Atlantic and Gulf on the east side and to Hudson Bay and the Arctic Ocean in the north.
Term
Deflation
Definition
A process of wind erosion that removes and lifts individual particles, literally blowing away unconsolidated, dry, or non cohesive sediments.
Term
Delta
Definition
A depositional plain formed where a river enters a lake or an ocean; named after the triangular shape of the Greek letter delta.
Term
Deposition
Definition
The process whereby weathered, wasted, and transported sediments are laid down by air, water and ice.
Term
Desertification
Definition
The expansion of deserts worldwide, related principally to poor agricultural practices (overgrazing and inappropriate agricultural practices), improper soil-moisture management, erosion and salinization, deforestation, and the ongoing climate change; an unwanted semipermanent invasion into neighboring biomes.
Term
Desert Pavement
Definition
On 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.
Term
Dissolved Load
Definition
Materials carried in chemical solution in a stream, derived from minerals such as limestone, dolomite, or from soluble salts.
Term
Drainage Basin
Definition
The basic spatial geomorphic unit of a river system; distinguished from a neighboring basin by ridges and highlands that form divides, marking the limits of the catchment area of the drainage basin or its watershed.
Term
Drainage Pattern
Definition
A distinctive 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.
Term
Drainage Density
Definition
A measure of the overall operational efficiency of a drainage basin, determined by the ratio of combined channel lengths to the unit area.
Term
Dune
Definition
A depositional feature of sand grains deposited in transient mounds, ridges, and hills; extensive areas of sand dunes are called sand seas.
Term
Eolian
Definition
Caused by wind; refers to the erosion, transportation, and deposition of materials; spelled aeolian in some countries.
Term
Erg Desert
Definition
A sandy desert, or area where sand is so extensive that it constitutes a sand sea.
Term
Erosion
Definition
Denudation by wind, water or ice, which dislodges, dissolves, or removes surface materials.
Term
Estuary
Definition
The point at which the mouth of a river enters the sea, where freshwater and seawater are mixed; a place where tides ebb and flow.
Term
Exotic Stream
Definition
A river that rises in a humid region and flows through an arid region. with discharge decreasing toward the mouth; for example, the Nile River and the Colorado River.
Term
Flash Flood
Definition
A sudden and short-lived torrent of water that exceeds the capacity of a stream channel; associated with desert and semiarid washes.
Term
Flood
Definition
A high water level that overflows the natural riverbank along any portion of a stream.
Term
Floodplain
Definition
A flat, low lying area along a stream channel, created by and subject to recurrent flooding; alluvial deposits generally mask underlying rock.
Term
Fluvial
Definition
Stream related processes.
Term
Graded Stream
Definition
An idealized condition in which a stream's load and the landscape mutually adjust. This forms a dynamic equilibrium among erosion, transported load, deposition, and the stream's capacity.
Term
Gradient
Definition
The drop in elevation from a stream's headwaters to its mouth, ideally forming a concave slope.
Term
Hydrology
Definition
The science of water, its global circulation, distribution, and properties, specifically water at and below Earth's surface.
Term
Hydraulic Action
Definition
The erosive work accomplished by the turbulence of water; causes a squeezing and releasing action in joints in bedrock; capable of prying and lifting rocks.
Term
Hydrograph
Definition
A graph of stream discharge (in cms or cfs) over a period of time (minutes, hours, days, years) at a specific place on a stream. The relationship between stream discharge and precipitation input is illustrated on the graph.
Term
Internal Drainage
Definition
In regions where river do not flow into the ocean, the outflow is through evaporation or subsurface gravitational flow. Portions of Africa, Asia, Australia, and the western United States have such drainage.
Term
Loess
Definition
Large quantities of fine-grained clays and silts left as glacial outwash deposits; subsequently blown by the wing great distances and redeposited as a generally unstratified, homogeneous blanket of material covering existing landscapes; in China, loess originated from desert lands.
Term
Meandering Stream
Definition
The sinuous, curving pattern common to graded streams, with the energetic outer portion of each curve subjected to the greatest erosive action and the lower-energy inner portion receiving sediment deposits.
Term
Natural Levee
Definition
A long, low ridge that forms on both sides of a stream in a developed floodplain; they are depositional products (coarse gravels and sand) of river flooding.
Term
Nickpoint (knickpoint)
Definition
The point at which the longitudinal profile of a stream is abruptly broken by a change in gradient; for example, a waterfall, rapids or cascade.
Term
Oxbow Lake
Definition
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 the looping meander. In Australia, known as a billabong.
Term
Playa
Definition
An area of salt crust left behind by evaporation on a desert floor usually in the middle of a desert or semiarid bolson or valley; intermittently wet and dry.
Term
Point Bar
Definition
In a stream the inner portion of a meander, where sediment fill is redeposited.
Term
Saltation
Definition
The transport of sand grains (usually larger than 0.2mm, or 0.008 in) by stream or wind, bouncing the grains along the ground in asymmetrical paths.
Term
Sand Sea
Definition
An extensive area of sand and dunes; characteristic of Earth's erg deserts.
Term
Sheet Flow
Definition
Surface water that moves downslope in a thin film as overland flow, not concentrated in channels larger than rills.
Term
Slipface
Definition
On a sand dune, formed as dune height increases above 30 cm (12in) on the leeward side at an angle at which loose material is stable - its angle of repose (30 to 34 degrees)
Term
Surface Creep
Definition
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.
Term
Suspended Load
Definition
Fine particles held in suspension in a stream. The finest particles are not deposited until the stream velocity nears zero.
Term
Traction
Definition
A type of sediment transport that drags coarser materials along the bed of a stream.
Term
Transport
Definition
The actual movement of weathered and eroded materials by air, water, and ice.
Term
Undercut Bank
Definition
In streams, a steep bank formed along the outer portion of a meandering stream; produced by lateral erosive action of a stream; sometimes called a cutbank.
Term
Ventifact
Definition
A piece of rock etched and smoothed by eolian erosion - abrasion by windblown particles.
Term
Wash
Definition
An intermittently dry steambed that fills with torrents of water after rare precipitation events in arid lands.
Term
Watershed
Definition
The catchment area of a drainage basin; delimited by divides.
Term
Yardang
Definition
A streamlined rock structure formed by deflation and abrasion; appears elongated and aligned with the most effective wind direction.
Term
Yazoo Tributary
Definition
A small tributary stream draining alongside a floodplain; blocked from joining the main river by its natural levees and elevated stream channel.
Term
Active Layer
Definition
A zone of seasonally frozen ground that exists between the subsurface permafrost layer and the ground surface. The active layer is subject to consistent daily and seasonal freeze-thaw cycles.
Term
Alfisols
Definition
A soil order in the Soil Taxonomy. Moderately weathered forest soils that are moist versions of Mollisols, with productivity dependent on specific patterns of moisture and temperature; rich in organics. Most wise-ranging of the soil orders.
Term
Alpine Glacier
Definition
A glacier confined in a mountain valley or walled basin, consisting of three subtypes: valley glacier (within a valley), piedmont glacier (coalesced at the base of a mountain, spreading freely over nearby lowlands), and outlet glacier (flowing outward from a continental glacier).
Term
Aridisols
Definition
A soil order in the Soil Taxonomy; largest soil order. Typical of dry climates; low in organic matter and dominated by calcification and salinization.
Term
Arete
Definition
A sharp ridge that divides two cirque basins. Derived from 'knife edge' in French, these form sawtooth and serrated ridges in glaciated mountains.
Term
Bergschrund
Definition
These form when a crevasse or wide crack opens along the headwall of a glacier; most visible in summer when covering snow is gone.
Term
Biodiversity
Definition
A principle of ecology and biogeography: the more diverse the species population in an eosystem (both in number of species quantity of members in each species, and genetic content), the more risk is spread over the entire community, which results in greater overall stability, greater productivity, and increased use of nutrients, as compared to a monoculture of little or no diversity.
Term
Biogeochemical Cycle
Definition
One of several circuits of flowing elements and materials (carbon, oxygen, nitrogen, phosphorus, water) that combine Earth's biotic (living) and abiotic (nonliving) systems; the cycling of materials is continuous and renewed through the biosphere and the life processes.
Term
Biogeography
Definition
The study of the distribution of plants and animals and related ecosystems; the geographical relationships with their environments over time.
Term
Biomass
Definition
The total mass of living organisms on Earth or per unit area of a landscape; also, the weight of the living organisms in an ecosystems.
Term
Brackish
Definition
Descriptive of seawater with a salinity of less than 35% for example, the Baltic Sea
Term
Breaker
Definition
The point where a wave's height exceeds its vertical stability and the wave breaks as it approaches the shore.
Term
Brine
Definition
Seawater with a salinity of more than 35%; for example, the Persian gulf.
Term
Calcification
Definition
The illuviated (deposited) accumulation of calcium carbonate or magnesium carbonate in the B and C soil horizons.
Term
Carnivore
Definition
A secondary consumer that principally eats meat for sustenance. The top carnivore in a food chain is considered a tertiary consumer.
Term
Carbon-exchange Capacity (CEC)
Definition
The ability of soil colloids to exchange cations between their surfaces and the soil solution; a measured potential that indicates soil fertility.
Term
Chlorophyll
Definition
A light-sensitive pigment that resides within chloroplasts (organelles) in leaf cells of plants.
Term
Cirque
Definition
A scooped out, amphitheater shaped basin at the head of an alpine glacier valley; an erosional landform.
Term
Community
Definition
A convenient biotic subdivision within an ecosystem; formed by interacting populations of animals and plants in an area.
Term
Consumer
Definition
Organism in an ecosystem that depends on producers (organisms that use carbon dioxide as their sole source of carbon) for its source of nutrients.
Term
Continental Glacier
Definition
A continuous mass of unconfined ice, covering at least 50,000 square kilometers (19,500 miles); most extensive at present as ice sheets covering Greenland and Antarctica.
Term
Coral
Definition
A simple, cylindrical marine animal with a saclike body that secretes calcium carbonate to form a hard external skeleton and, cumulatively, landforms called reefs; lives sybiotically with nutrient-producing algae; presently in a worldwide state of decline due to bleaching.
Term
Crevasse
Definition
A vertical crack that develops in a glacier as a result of friction between valley walls, or tension forces of extension on convex slopes, or compression forces on concave slopes.
Term
Detritvores
Definition
Detritus feeders and decomposers that consume, digest, and destroy organic wastes and debris. Worms, mites, termites, centipedes, snails, crabs, even vultures.
Term
Drumlin
Definition
A depositional landform related to glaciation that is composed of till (unstratified, unsorted) and is streamlined in the direction of continental ice movement - blunt end upstream and tapered end downstream with a rounded summit.
Term
Ebb tide
Definition
Falling of lowering tide during the daily tidal cycle
Term
Ecological Succession
Definition
The process whereby different and usually more complex assemblages of plants and animals replace older and usually simpler communities; communities are in a constant state of change as each species adapts to conditions. Ecosystems do not exhibit a stable point of successional climax condition as previously thought.
Term
Ecosystem
Definition
A self regulating association of living plants, animals, and their nonliving physical and chemical environments.
Term
Entisols
Definition
A soil order in the Soil Taxonomy. Specifically lacks vertical development of horizons; usually young or undeveloped. Found in active slopes, alluvial-filled floodplains, poorly drained tundra.
Term
Eluviation
Definition
The removal of finer particles and minerals from the upper horizons of soil; an erosional process within a soil body.
Term
Esker
Definition
A sinuously curving, narrow deposit of coarse gravel that forms along a meltwater stream channel, developing a tunnel beneath a glacier.
Term
Fire Ecology
Definition
The study of fire as a natural agent and dynamic factor in community succession.
Term
Firn
Definition
Snow of a granular texture that is transitional in the slow transformation from snow to glacial ice; snow that has persisted through a summer season in the zone of accumulation.
Term
Firn Line
Definition
The snow line that is visible on the surface of a glacier, where winter snows survive the summer ablation season; analogous to a snow line on land.
Term
Fjord
Definition
A drowned glaciated valley, or glacial trough, along a seacoast.
Term
Flood Tide
Definition
Rising tide during the daily tidal cycle
Term
Gelifluction
Definition
Refers to soil flow in periglacial environments, a progressive, lateral movement; a type of solidfluction formed under periglacial conditions of permafrost and frozen ground.
Term
Glacial Drift
Definition
The general term for all glacial deposits, both unsorted and sorted.
Term
Glacial Ice
Definition
A hardened form of ice, very dense in comparison to normal snow or firn.
Term
Glacier
Definition
A large mass of perennial ice resting on land or floating shelflike in the sea adjacent to the land; formed from the accumulation and recrystallization of snow, which then flows slowly under the pressure of its own weight and the pull of gravity.
Term
Glacier Surge
Definition
The rapid, lurching, unexpected forward movement of a glacier.
Term
Gleization
Definition
A process of humus and clay accumulation in cold, wet climates with poor drainage.
Term
Ground Ice
Definition
Subsurface water that is frozen in regions of permafrost. The moisture content of areas with ground ice may very from nearly absent in regions of drier permafrost to almost 100% in saturated soils.
Term
Histosols
Definition
A soil order in the Soil Taxonomy. Formed from thick accumulations of organic matter, such as beds of former lakes, bogs, and layers of peat.
Term
Horn
Definition
A pyramidal, sharp-pointed peak that results when several cirque glaciers gouge an individual mountain summit from all sides.
Term
Ice Age
Definition
A cold episode, with accompanying alpine and continental ice accumulations, that has repeated roughly every 200 to 300 million years since the late Precambian era (1.25 billion years ago); includes the most recent episode during the Pleistocene Ice Age, which began 1.65 million years ago.
Term
Iceberg
Definition
Floating ice created by ice calving (a large piece breaking off) and floating adrift; a hazard to shipping because about nine-tenths of the ice is submerged and can be irregular in form.
Term
Ice Cap
Definition
A large, dome-shaped glacier, with mountain ridges and peaks visible above the ice; less than an ice cap or ice sheet, although it buries mountain peaks and the local landscape.
Term
Ice Field
Definition
The least extensive form of a glacier, with mountain ridges and peaks visible above the ice; less than an ice cap or ice sheet.
Term
Ice Sheet
Definition
An enormous continuous continental glacier. The bulk of glacial ice on Earth covers Antarctica and Greenland in two ice sheets.
Term
Ice Wedge
Definition
Formed when water enters a thermal contraction crack in permafrost and freezes. Repeated seasonal freezing and melting of the water progressively expands the wedge.
Term
Illuviation
Definition
The downward movement and deposition of finer particles and minerals from the upper horizon of the soil; a depositional process. Deposition usually is the B horizon, where accumulations of clays, aluminium, carbonates, iron, and some humus occur.
Term
Inceptisols
Definition
A soil order in the Soil Taxonomy. Weakly developed soils that are inherently infertile; usually young soils that are weakly developed, although they are more developed than Entisols.
Term
Kame
Definition
A depositional feature of glaciation; a small hill of poorly sorted sand and gravel that accumulates in crevasses or in ice-caused indentations in the surface.
Term
Kettle
Definition
Forms when an isolated block of ice persists in a ground moraine, an outwash plain, or valley floor after a glacier retreats; as the block finally melts, it leaves behind a steep-sided hole that frequently fills with water.
Term
Lateral Moraine
Definition
Debris transported by a glacier that accumulates along the sides of the glacier and is deposited along these margins.
Term
Laterization
Definition
A pedogenic process operating in well-drained soils that occur in warm and humid regions; typical of Oxisols. Plentiful precepitation leaches soluable minerals and soil constituents. Resulting soils usually are reddish or yellowish.
Term
Laterization
Definition
A pedogenic process operating in well-drained soils that occur in warm and humid regions; typical of Oxisols. Plentiful precepitation leaches soluable minerals and soil constituents. Resulting soils usually are reddish or yellowish.
Term
Littoral Drift
Definition
Transport of sand, gravel, sediment, and debris along the shore; a more comprehensive term, considers beach drift and longshore drift combined.
Term
Litteral Zone
Definition
A specific coastal enviornment; that region between the high water line during a storm and a depth at which storm waves are unable to move sea-floor sediments.
Term
Loam
Definition
A soil that is a mixture of sand, silt, and clay in almost equal proportions, with no one texture dominant; an ideal agricultural soil.
Term
Mangrove Swamp
Definition
A wetland ecosystem between 30 degrees North or South and the equator; tends to form a distinctive community of mangrove plants.
Term
Mean sea level (MSL)
Definition
The average of tidal levels recorded hourly at a given site over a long period, which must be at least a full lunar tide.
Term
Medial Moraine
Definition
Debris transported by a glacier that accumulates down the middle of a glacier, resulting from two glaciers merging their lateral moraines; forms a depositional feature following glacial retreat.
Term
Mollisols
Definition
A soil order in the Soil Taxonomy. These have a mollic epipedon and a humus-rich organic content high in alkalinity. Some of the world's most significant agricultural soils.
Term
Moraine
Definition
Marginal glacial deposits (lateral, medial, terminal, ground) of unsorted and unstratified material.
Term
Neap Tide
Definition
Unusually low tidal range produced during the first and third quarters of the Moon, with an offsetting pull from the Sun.
Term
Outwash Plain
Definition
Glacial stream deposits of stratified drift of meltwater fed, braided, and overloaded streams; occurs beyond a glacier's morainal deposits.
Term
Oxisols
Definition
A soil order in the Soil Taxonomy. Tropical soils that are old, deeply developed, and lacking in horizons wherever well drained; heavily weathered, low in cation-exchange capacity, and low in fertility.
Term
Paleolake
Definition
An ancient lake, such as Lake Bonneville or Lake Lahonton, associated with former wet periods when the lake basins were filled to higher levels than today.
Term
Palsa
Definition
A rounded or elliptical mound of peat that contains thin perennial ice lenses rather than an ice core, as in a pingo, Palsas can be 2 to 30 m wide by 1 to 10 m high and usually are covered by soil or vegetation over a cracked surface.
Term
Polypedon
Definition
The identifiable soil in an area, with distinctive characteristics differentiating it from surrounding polypedons that form the basic mapping unit.