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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. |
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Definition
| The study of the climate. |
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Definition
| An are of homogenous climate that features characteristics regional weather and air mass patterns. |
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Definition
| The process of ordering or grouping data or phenomena in related classes; results in a regular distribution of information; a taxonomy. |
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Definition
| A graph that plots, daily, monthly, or annual temperature and precipitation values for a selected station; may also include additional weather information. |
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Definition
| A climate classification based on weather statistics or other data; used to determine general climate categories. |
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Term
| General Circulation Model (GCM) |
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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. |
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Definition
| General Circulation Model |
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Definition
| A climate classification that uses causative factors to determine climatic regions; for example, an analysis of the effect of interacting air masses. |
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Definition
| The science that studies the climates, and the causes of variations in climate, of past ages, throughout historic and geological time. |
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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. |
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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. |
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Definition
| A common extrusive igneous rock, fine-grained, comprising the bulk of the ocean-floor crust, lava flows, and volcanic forms. |
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Definition
| The largest plutonic form exposed at the surface; an irregular intrusive mass; it invades crustal rocks, cooling slowly so that large crystals develop. |
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| 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. |
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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. |
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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. |
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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. |
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| 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. |
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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. |
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Definition
| A general term characterizing the vast cycling that proceeds in the lithosphere. It encompasses the hydrologic cycle, tectonic cycle, and rock cycle. |
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| 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. |
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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. |
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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. |
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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. |
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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. |
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Definition
| One of the basic rock types; it has solidified and crystallized form a hot molten state (either magma or lava). |
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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. |
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Definition
| Magma that issues from volcanic activity onto the surface; the extrusive rock that results when magma solidifies. |
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Definition
| The most common chemical factor that most inhibits biotic processes, either through lack or excess. |
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Definition
| The compaction, cementation, and hardening of sediments into sedimentary rock. |
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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. |
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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. |
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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. |
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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. |
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Definition
| An element or combination of elements that forms an inorganic natural compound; described by a specific formula and crystal structure. |
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Term
| Mohorovicic Discontinuity (Moho) |
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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. |
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Definition
| The super continent formed by the collision of all continental masses approximately 225 million years ago. |
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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. |
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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. |
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Definition
| An assemblage of minerals bound together, or sometimes a mass of a single mineral. |
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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. |
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Definition
| The mechanism driving the movement of the continents; associated with upwelling flows of magma along the worldwide system of mid-ocean ridges. |
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Definition
| One of three basic rock types; formed from the compaction, cementation, and hardening of sediments derived from other rocks. |
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Definition
| A science that analyzes the sequence, spacing, geophysical and geochemical properties, and spatial distribution of rock strata. |
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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. |
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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. |
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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. |
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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. |
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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. |
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Definition
| Upfolded rock strata, in which layers slope downward from the axis of the fold, or central ridge. |
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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. |
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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. |
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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. |
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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. |
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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. |
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Definition
| A tectonically and volcanically active region encircling the Pacific Ocean; also known as the Ring of Fire. |
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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. |
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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. |
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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. |
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Definition
| A mass of falling and tumbling rock, debris, and soil; can be dangerous because of the tremendous velocities achieved by the onrushing materials. |
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Definition
| A general term that refers to all processes that cause the degradation of the landscape; weathering, mass movement, erosion and transport. |
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Definition
| The effect of different resistances in rock, coupled with variations in the intensity of physical and chemical weathering. |
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Term
| Dynamic Equilibrium Model |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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Definition
| The process whereby displacement and fracturing occur between two portions of Earth's crust; usually associated with earthquake activity. |
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Definition
| The bending and deformation of beds of rock strata subjected to compressional forces. |
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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. |
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Definition
| The threshold up to which landforms changed before lurching to a new set of relationships, with rapid realignments of landscape materials and slopes. |
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Definition
| The science that analyses and describes the origin, evolution, form, classification, and spatial distribution of landforms. |
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Definition
| Pairs or groups of faults that produce downward-faulted blocks; characteristic of the basins of the interior western United States. |
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Definition
| Upward-faulted blocks produced by pairs or groups of faults; characteristic of the mountain ranges of the interior of the western United States. |
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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. |
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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. |
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Definition
| A fracture or separation in rock that occurs without displacement of the sides; increases the surface area of rock exposed to weathering processes. |
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Definition
| Distinctive topography formed in a region of chemically weathered limestone with poorly developed surface drainage and solution features that appear pitted and bumpy. |
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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. |
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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. |
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Definition
| Gravitational movement of non unified material downslope; a specific form of mass movement. |
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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. |
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Definition
| Fluid downslope flows of material containing more water than earthflows. |
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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. |
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Definition
| The physical container (a depression in the lithosphere) holding an ocean. |
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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. |
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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. |
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Definition
| Basaltic lava that is more fluid than aa. Pahoehoe forms a thin crust that forms folds and appears ropy, like coiled twisted rope. |
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Definition
| The unconsolidated material, from both organic and mineral sources, that is the basis of soil development. |
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Definition
| The breaking and disintegrating of rock without any chemical alteration; sometimes referred to as mechanical or fragmentation weathering. |
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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. |
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Definition
| An explosively ejected rock fragment launched by a volcanic eruption; sometimes described by the more general term tephra. |
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Definition
| Partially weathered rock overlying bedrock, whether residual or transported. |
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Definition
| Elevation differences in a lock landscape; an expression of local height difference of landforms. |
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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. |
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Definition
| An open ended, logarithmic scale that estimates earthquakes magnitude now replaced by the moment magnitude scale. |
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Definition
| A tectonically and volcanically active region encircling the Pacific Ocean. |
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Definition
| Free-falling movement of debris from a cliff or steep slope, generally falling straight of bounding downslope. |
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Definition
| Human-induced mass movements of Earth materials, such as large scale open pit mining and strip mining. |
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Definition
| Fine-grained mineral matter that is transported and deposited by air, water or ice. |
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Definition
| A device that measures seismic waves of energy transmitted throughout Earth's interior or along the coast. |
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Definition
| A form of weathering associated with fracturing or fragmentation of rock by pressure release; often related to exfoliation processes. |
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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. |
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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. |
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Definition
| A curved. inclined surface that bounds a landforms. |
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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. |
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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. |
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Definition
| A trough in folded strata, with beds that slope toward the axis of the downfold. |
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Definition
| Formed by angular rock fragments that cascade down a slope along the base of a mountain; poorly sorted, cone-shaped deposits. |
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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. |
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Definition
| A reverse fault where the fault plane forms a low angle relative to the horizontal; an overlying block moves over an underlying block. |
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Definition
| The undulations and configurations, including its relief, that give Earth's surface its texture; portrayed on topographic maps. |
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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. |
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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. |
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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. |
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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. |
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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. |
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Definition
| Fan-shaped fluvial landform at the month of a canyon; generally occurs in arid landscapes where streams are intermittent. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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Definition
| Eolian (wind) erosion in which deflation forms a basin in areas of loose sediment. Diameter may range up to hundreds of meters. |
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Definition
| The slope and basin area between the crests of two adjacent ridges in a dry region. |
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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. |
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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. |
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Definition
| A process of wind erosion that removes and lifts individual particles, literally blowing away unconsolidated, dry, or non cohesive sediments. |
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Definition
| A depositional plain formed where a river enters a lake or an ocean; named after the triangular shape of the Greek letter delta. |
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Definition
| The process whereby weathered, wasted, and transported sediments are laid down by air, water and ice. |
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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. |
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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. |
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Definition
| Materials carried in chemical solution in a stream, derived from minerals such as limestone, dolomite, or from soluble salts. |
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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. |
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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. |
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Definition
| A measure of the overall operational efficiency of a drainage basin, determined by the ratio of combined channel lengths to the unit area. |
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Definition
| A depositional feature of sand grains deposited in transient mounds, ridges, and hills; extensive areas of sand dunes are called sand seas. |
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Definition
| Caused by wind; refers to the erosion, transportation, and deposition of materials; spelled aeolian in some countries. |
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Definition
| A sandy desert, or area where sand is so extensive that it constitutes a sand sea. |
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Term
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Definition
| Denudation by wind, water or ice, which dislodges, dissolves, or removes surface materials. |
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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. |
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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. |
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Definition
| A sudden and short-lived torrent of water that exceeds the capacity of a stream channel; associated with desert and semiarid washes. |
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Definition
| A high water level that overflows the natural riverbank along any portion of a stream. |
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Term
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Definition
| A flat, low lying area along a stream channel, created by and subject to recurrent flooding; alluvial deposits generally mask underlying rock. |
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Definition
| Stream related processes. |
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Term
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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. |
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Definition
| The drop in elevation from a stream's headwaters to its mouth, ideally forming a concave slope. |
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Definition
| The science of water, its global circulation, distribution, and properties, specifically water at and below Earth's surface. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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Definition
| In a stream the inner portion of a meander, where sediment fill is redeposited. |
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Term
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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. |
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Definition
| An extensive area of sand and dunes; characteristic of Earth's erg deserts. |
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Definition
| Surface water that moves downslope in a thin film as overland flow, not concentrated in channels larger than rills. |
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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) |
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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. |
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Term
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Definition
| Fine particles held in suspension in a stream. The finest particles are not deposited until the stream velocity nears zero. |
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Term
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Definition
| A type of sediment transport that drags coarser materials along the bed of a stream. |
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Term
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Definition
| The actual movement of weathered and eroded materials by air, water, and ice. |
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Term
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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. |
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Definition
| A piece of rock etched and smoothed by eolian erosion - abrasion by windblown particles. |
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Definition
| An intermittently dry steambed that fills with torrents of water after rare precipitation events in arid lands. |
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Definition
| The catchment area of a drainage basin; delimited by divides. |
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Definition
| A streamlined rock structure formed by deflation and abrasion; appears elongated and aligned with the most effective wind direction. |
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Definition
| A small tributary stream draining alongside a floodplain; blocked from joining the main river by its natural levees and elevated stream channel. |
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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. |
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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. |
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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). |
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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. |
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Definition
| A sharp ridge that divides two cirque basins. Derived from 'knife edge' in French, these form sawtooth and serrated ridges in glaciated mountains. |
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Term
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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. |
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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. |
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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. |
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Definition
| The study of the distribution of plants and animals and related ecosystems; the geographical relationships with their environments over time. |
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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. |
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Definition
| Descriptive of seawater with a salinity of less than 35% for example, the Baltic Sea |
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Term
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Definition
| The point where a wave's height exceeds its vertical stability and the wave breaks as it approaches the shore. |
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Term
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Definition
| Seawater with a salinity of more than 35%; for example, the Persian gulf. |
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Term
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Definition
| The illuviated (deposited) accumulation of calcium carbonate or magnesium carbonate in the B and C soil horizons. |
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Definition
| A secondary consumer that principally eats meat for sustenance. The top carnivore in a food chain is considered a tertiary consumer. |
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Term
| Carbon-exchange Capacity (CEC) |
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Definition
| The ability of soil colloids to exchange cations between their surfaces and the soil solution; a measured potential that indicates soil fertility. |
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Term
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Definition
| A light-sensitive pigment that resides within chloroplasts (organelles) in leaf cells of plants. |
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Term
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Definition
| A scooped out, amphitheater shaped basin at the head of an alpine glacier valley; an erosional landform. |
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Term
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Definition
| A convenient biotic subdivision within an ecosystem; formed by interacting populations of animals and plants in an area. |
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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. |
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Term
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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. |
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Term
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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. |
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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. |
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Definition
| Detritus feeders and decomposers that consume, digest, and destroy organic wastes and debris. Worms, mites, termites, centipedes, snails, crabs, even vultures. |
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Term
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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. |
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Term
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Definition
| Falling of lowering tide during the daily tidal cycle |
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Term
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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. |
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Definition
| A self regulating association of living plants, animals, and their nonliving physical and chemical environments. |
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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. |
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Term
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Definition
| The removal of finer particles and minerals from the upper horizons of soil; an erosional process within a soil body. |
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Term
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Definition
| A sinuously curving, narrow deposit of coarse gravel that forms along a meltwater stream channel, developing a tunnel beneath a glacier. |
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Term
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Definition
| The study of fire as a natural agent and dynamic factor in community succession. |
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Term
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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. |
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Term
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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. |
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Term
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Definition
| A drowned glaciated valley, or glacial trough, along a seacoast. |
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Term
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Definition
| Rising tide during the daily tidal cycle |
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Term
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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. |
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Term
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Definition
| The general term for all glacial deposits, both unsorted and sorted. |
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Term
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Definition
| A hardened form of ice, very dense in comparison to normal snow or firn. |
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Term
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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. |
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Term
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Definition
| The rapid, lurching, unexpected forward movement of a glacier. |
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Term
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Definition
| A process of humus and clay accumulation in cold, wet climates with poor drainage. |
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Term
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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. |
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Term
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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. |
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Term
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Definition
| A pyramidal, sharp-pointed peak that results when several cirque glaciers gouge an individual mountain summit from all sides. |
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Term
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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. |
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Term
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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. |
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Term
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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. |
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Term
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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. |
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Term
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Definition
| An enormous continuous continental glacier. The bulk of glacial ice on Earth covers Antarctica and Greenland in two ice sheets. |
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Term
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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. |
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Term
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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. |
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Term
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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. |
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Term
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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. |
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Term
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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. |
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Term
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Definition
| Debris transported by a glacier that accumulates along the sides of the glacier and is deposited along these margins. |
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Term
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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. |
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Term
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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. |
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Term
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Definition
| Transport of sand, gravel, sediment, and debris along the shore; a more comprehensive term, considers beach drift and longshore drift combined. |
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Term
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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. |
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Term
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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. |
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Term
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Definition
| A wetland ecosystem between 30 degrees North or South and the equator; tends to form a distinctive community of mangrove plants. |
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Term
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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. |
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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. |
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Term
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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. |
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Term
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Definition
| Marginal glacial deposits (lateral, medial, terminal, ground) of unsorted and unstratified material. |
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Term
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Definition
| Unusually low tidal range produced during the first and third quarters of the Moon, with an offsetting pull from the Sun. |
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Term
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Definition
| Glacial stream deposits of stratified drift of meltwater fed, braided, and overloaded streams; occurs beyond a glacier's morainal deposits. |
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Term
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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. |
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Term
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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. |
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Term
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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. |
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Term
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Definition
| The identifiable soil in an area, with distinctive characteristics differentiating it from surrounding polypedons that form the basic mapping unit. |
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