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100 Cards in this Set
- Front
- Back
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geotherm |
the curve that describes how Earth's temperature increases with depth |
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seismic tomography |
a technique that uses difference in the travel times of seismic waves produced by earthquakes and recorded on seismographs to construct three-dimensional images of Earth's interior |
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normal magnetic polarity |
the current positions of the North and South Pole |
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reverse magnetic polarity |
every few hundreds of years, the North and South Pole switch places, reversing the Earth's magnetic field |
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secular magnetic variation |
changes in Earth's magnetic field on time scales of about a year or more; changes mostly reflect the Earth's interior |
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magnetic stratigraphy |
geophysical correlation technique used to date sedimentary and volcanic sequences; used to determine the polarity of the Earth's magnetic field at the time a stratum was deposited |
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cryosphere |
the frozen water part of the Earth system |
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hydrosphere |
the combined mass of water found on, under, and over the surface of a planet, includes water in liquid and frozen forms |
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atmosphere |
a layer of gases surrounding a planet or other material body of sufficient mass that is held in place by the gravity of the body; the atmosphere of Earth is primarily made up of nitrogen, oxygen, and carbon dioxide |
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troposphere |
the lowest portion of Earth's atmosphere, contains approximately 75% of the atmosphere's mass and 99% of its water vapor; its average depth is approximately 17km |
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albedo |
the fraction of solar energy reflected by a surface |
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Milankovitch cycles |
A pattern of periodic variations in Earth's movement around the Sun that affects the amount of solar energy received at Earth's surface; Milankovitch cycles include variations in the eccentricity of Earth's orbit, the tilt of Earth's axis of rotation, and precession-- Earth's wobble about its axis of rotation |
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residence time |
the average time an atom of a particular element spends in a geochemical reservoir before leaving it |
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physical weathering |
weathering in which solid rock is fragmented by mechanical processes that do not change its chemical composition |
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chemical weathering |
weathering in which the minerals in a rock are chemically altered or dissolved |
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clay |
a siliclastic sediment in which most of the particles are less than .0039mm in diameter and which consists largely of clay minerals, the most abundant component of fine-grained sedimentary rocks |
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kaolinite |
a white to cream-colored clay produced by the weathering of feldspar |
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ferrous iron |
equivalent of iron (II) oxide; makes up about 9% of the Earth's mantle; may be electrically conductive, which is a possible explanation for perturbations in Earth's rotation that do not fit with the normal explanations provided by the mantle's other properties |
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ferric iron |
equivalent of iron (III) oxide; also known as hematite or rust; the main source of iron for the steel industry; the most stable form of iron in air |
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hematite |
the principle iron ore, the most abundant iron oxide at Earth's surface |
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joint |
a crack in a rock along which there has been no appreciable movement |
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frost wedging |
a physical weathering process in which the expansion of freezing water in cracks in rock breaks the rock |
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exfolation |
a physical weathering process in which large flat or curved sheets of rock are detached from an outcrop |
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angle of repose |
the maximum angle at which a slope of loose material can lie without sliding downhill |
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rockslide |
a type of mass wasting in which rock debrisdetaches and slides down a slope under the influence of gravity; the movementusually occurs over a planar surface such as a bedding plane, joint surface, orfault plane; the moving mass can break up during transport or remain in a largemass |
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earthflow |
a downslope movement of soil and debris that isconfined to a well-defined “chute” and spreads out over the run-out area in theform of a lobe; the material is mostly fine-grained and moves as a “flow”instead of as a rotating mass; most earthflows have a very high moisturecontent but dry flows are also possible
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debris flow |
a type of mass movement in which a combinationof rocks, soil, organic matter, air, and water flow downslope as a slurry;debris flows differ from mud flows because they are mainly rock materialinstead of mud; they can be triggered by heavy precipitation, rapid snow melt,or vibrations |
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debris avalanche |
the very sudden downslope movement of rock andsoil on a steep slope; a debris avalanche differs from a debris flow mainly onthe basis of its speed |
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slump |
a slow mass movement of unconsolidated material that travels as a unit |
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hydrology |
the science that studies the movements and characteristics of water on and under Earth's surface |
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groundwater |
the volume of water that flows beneath Earth's surface |
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infiltration |
the movement of water into rock or soil through cracks or small pores between particles |
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precipitation |
a deposit on Earth's surface of condensed atmospheric water vapor in the form of rain, sleet, snow, hail, or mist |
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sublimation |
the process by which a solid is deposited directly from a gas without going through a liquid phase sublimation frequently occurs around volcanic vents where certain minerals are deposited |
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transportation |
the movement of material across the Earth's surface by water, wind, ice, or gravity; one of the two phases of erosion (the other is weathering) |
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rain shadow |
an area of low rainfall on the leeward slope of a mountain range |
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recharge |
the infiltration of water into any subsurface rock formation |
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discharge |
the volume of groundwater leaving an aquifer in a given time or the volume of water that passes a given point in a given time as it flows through a channel of a certain width and depth |
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aquiclude |
a relatively impermeable formation that bounds an aquifer above or below and acts as a barrier to the flow of groundwater |
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cone of depression |
a cone-shaped lowering of the water table around a producing well, as water is pumped, the water level in the well falls and width of the cone increases, when pumping stops, the cone shrinks in size because water from adjacent land flows to fill it |
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karst topography |
an irregular, hilly type terrain characterized by sinkholes, caves, and a lack of surface streams, formed in regions with humid climates, abundant vegetation, extensively jointed limestone formations, and appreciable hydraulic gradients |
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meteoric water |
rain, snow, or other forms of water derived from the atmosphere |
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floodplain |
a flat area about level with the top of a channel that lies on either side of the channel, the part of a valley that is flooded when a stream overflows its banks |
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drainage basin |
an area of land, bounded by divides, that funnels all its water into the network of streams draining the area |
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drainage divide |
a ridge of high ground along which all rainfall runs off down one side or the other |
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laminar flow |
fluid movement in which straight or gently curved streamlines run parallel to one another without mixing or crossing between layers |
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turbulent flow |
fluid movement in which streamlines mix, cross, and form swirls and eddies |
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saltation |
the transportation of sand or smaller sediment particles by a current in such a manner that the particles move along in a series of short intermittent jumps |
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settling velocity |
the speed at which particles of various weights suspended in a current settle to the bed
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dune |
an elongated mound or ridge of sand formed by a current of wind or water |
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ripple |
a very small ridge of sand or silt whose long dimension is at right angles to the current that formed it |
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base level |
the elevation at which a stream ends by entering a large standing body of water |
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topset delta bed |
a horizontal bed of sediment, typically sand, deposited on top of a delta |
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foreset delta bed |
a gently inclined deposit of fine-grained sand and silt, resembling large-scale cross-beds on the outer front of a delta |
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bottomset delta bed |
a thin, horizontal bed of mud deposited seaward of a delta and then buried by continue delta growth |
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allvial fan |
a cone or fan-shaped accumulation of sediment deposited where a stream widens abruptly as it leaves a mountain front and enters a broad, relatively flat valley |
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steam terrace |
elongated terraces that flank the sides of floodplains and fluvial valleys all over the world; these terraces lie parallel to and above the river channel and its floodplain; fluvial terraces are underlain by fluvial sediments of highly variable thickness |
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desertification |
the transformation of semiarid lands into deserts |
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eolian |
pertaining to wind |
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ventifact |
a pebble with several curved or almost flat surfaces that meet at sharp ridges, formed by sandblasting of the pebble's windward side |
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sandblasting |
erosion of a solid surface by abrasion caused by the high-speed impact of sand grains carried by wind |
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deflation |
the removal of clay, silt, and sand from dry soil by strong winds, which gradually scoop out shallow depressions in the ground |
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desert pavement |
a coarse gravelly ground surface left when continued deflation removes the smaller sand and silt particles from desert soils |
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slip face |
the steep leeward slope of a dune on which sand is deposited in cross-beds at the angle of repose |
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loess |
a blanket of unstratified, wind-deposited, fine-grained sediment |
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playa lake |
a permanent or temporary lake in an arid mountain valley or basin, where dissolved minerals may be concentrated and precipitated as the valley evaporates |
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swell |
a series of mechanical waves that propagate along the interface between water and air and so they are often referred to as surface gravity waves; generated by distant weather systems; the winds of a swell are not really affected by local winds |
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surf |
the breaking of waves as the enter shallow water |
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swash |
the rush of a breaking of a breaking wave up on the slope of a beach |
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wavelength |
an interval or repetition in a wave-like disturbance; the distance between two successive crests or two successive troughs |
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wave height |
the difference between the elevations of a crest and a neighboring trough, more or less corresponds to what is observed when visually estimating the average wave height |
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wave period |
the time required for two successive wave crests to pass a fixed point, or the time for a single wave crest to travel a distance equal to the length of the wave |
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rip current |
a strong, narrow current of high velocity and short duration that flows seaward through the breaker zone; caused when a buildup of water pushed onto the beach by winds and waves returns seward |
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storm surge |
a dome of seawater, formed by a hurricane, that rises above the level of the surrounding ocean surface |
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wave-cut terrace |
a level surface formed by wave erosion of a rocky shoreline beneath the surf zone, which may be visible at low tide |
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barrier island |
a long, offshore sandbar that builds up to form a barricade between open ocean waves and the main shoreline |
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passive continental margin |
a continental margin far from a plate boundary |
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active continental margin |
a continental margin where tectonic forces caused by plate movements are actively deforming the continental crust |
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turbidity current |
a turbulent flow of water carrying a suspended load of mud that flows down the continental slope beneath the overlying clear water |
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turbidite |
a seafloor sediment sequence deposited by a turbidity current; the turbidity current flows down a continental slope eroding surface sediment as it travels; then, as it begins to slow, the coarsest grains are dropped following by grains of increasingly finer size; this produces a graded sequence of sediment with the coarsest grain sizes at the bottom and finer grain sizes going upwards |
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pelagic sediment |
an open-ocean sediment composed of small terrigenous and biologically precipitated particles that slowly settle out of suspension in seawater |
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foraminiferal ooze |
a sandy and silty sediment composed of the shells of dead foraminifera |
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siliceous ooze |
a biologically precipitated pelagic sediment produced by sedimentation of the silica shells of diatoms and radiolarians |
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valley glacier |
a river of ice that forms in the cold heights of a mountain range, where snow accumulates, then moves downslope, either flowing down an existing stream valley or carving out a new valley |
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continental glacier |
a thick, slow-moving sheet of ice that covers a large part of a continent or other large landmass |
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ice shelf |
a thick floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface, found in Antarctica, Greenland, and Canada |
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granular ice |
an ice type with irregular particle sizes; can vary from small pieces that look like coarse snow to up to 9mm thick, used for industrial purposes |
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firn |
a type of snow that has been left over from past seasons and has been recrystallized into a denser substance; ice that is at an intermediate stage between snow and glacial ice |
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glacial ice |
a persistent body of dense ice that is constantly moving under its own weight, it forms where the accumulation of snow exceeds its melting and sublimation over many years, forms only on land |
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glacial surge |
short-lived events where a glacier can advance substantially, moving at velocities up to 100 times faster than normal, glaciers can retreat substantially during the time in between glacial surges |
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crevasse |
a deep crack or fracture, found in an ice sheet or glacier as opposed to a crevice that forms in rock, form as a result of the movement and resulting stress associated with the shear stress generated when two semi-rigid pieces above a plastic substrate have different rates of movement |
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permafrost |
perennially frozen soil containing aggregates of ice crystals, any rock or soil remaining at or below 0 degrees Celsius for 2 or more years |
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tillite |
the lithified equivalent of till |
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contour |
a line that connects points of equal elevation on a topographic map |
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relief |
the difference between the highest and lowest elevations in a particular area |
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landform |
a characteristic landscape feature on Earth's surface shaped by the processes of erosion and sedimentaiton |
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stream power |
the product of stream slope and stream discharge |
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badland |
a deeply gullied landscape resulting from the rapid erosion of easily erodible shales and clays |
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cuesta |
an asymmetrical ridge formed from a tilted and eroded series of beds with alternating weak and strong resistance to erosion |
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hogback |
a landscape feature similar to a cuesta, consisting of steep, narrow, more or less symmetrical ridges, formed by the erosion of steeply dipping or vertical beds of hard strata |
