GLOSSARY OF SOME LANDFORM TERMS

Dr. Miriam Helen Hill

  • alluvium--material deposited by a stream.
  • alluvial fan--a gently sloping conical deposit formed by a stream emerging from a steep narrow valley onto a broader lowland.
  • alpine glacier--glacier originating in a mountainous area.
  • annular drainage pattern--an interrupted radial pattern with structural control reflected as a bent trellis.
  • antecedent stream--stream which cuts down as the area is upwarped.
  • anticline--upfold of rock layers.
  • arête--a narrow saw-tooth ridge formed by glacial erosion on opposite sides of the ridge.
  • arroyo--the dry stream channel found in areas of arid climate.
  • atoll--circular coral reef.
  • avalanche--mass movement downslope of large blocks of ice and other materials.
  • backswamp--marsh on a poorly drained floodplain.
  • bajada--depositional surface formed by coalescing alluvial fans
  • barchan--sand dune with crescent shape and horns pointing downwind.
  • barrier island--an island parallel to the main land, may be an offshore bar.
  • basin--oval or circular downfold of rock layers.
  • batholith--large deep mass of intrusive igneous rock.
  • baymouth bar--a sandbar extending across the mouth of a bay or cove.
  • beach--the area between high tide and low tide or the area of coastal deposits.
  • beach ridge--remnants of past shoreline.
  • beheaded stream--stream which has had the headwaters diverted by stream capture or stream piracy.
  • blowout--a depression formed by wind erosion.
  • braided stream--a network of small, shallow, interlaced stream channels formed with alluvium has been deposited in the channel.
  • butte--a small, flat-topped upland formed in arid climates; a small mesa.
  • caldera--large, cup-like depression in a volcano resulting from an explosion or subsidence.
  • cavern--large cave formed by erosion by ground water.
  • centripetal drainage pattern--streams flow into an interior basin or common center.
  • cinder cone--small, steep-sided volcanic cone composed of pyroclastic materials blown out of the volcano which have collected around the vent.
  • cirque--a steep, blunt, bowl-shaped valley head in a mountainside at a high elevation, formed by glacial plucking and frost action at the head of a glacier.
  • cirque glacier--type of alpine glacier which occupies a cirque but does not extended beyond the mountain top.
  • col--a saddle on a divide, such as a pass through a glaciated mountain ridge, gap or pass through an arête.
  • composite cone--volcanic cone composed of alternating layers of lava and pyroclastic materials.
  • consequent stream--stream which flows down the original slope of the land.
  • contact--separates one rock from another rock; the line between two different rocks on a geologic map.
  • continental ice sheet--large, irregularly shaped mass of recrystallized ice that acts like a plastic and flows outward and downward because of gravity.
  • cove--a small bay or indentation into the coastline.
  • crater--central cup-like depression in a volcano.
  • creep--a slow type of mass movement affecting soil and near surface materials on a slope.
  • cusp--smoothly, curved beach deposits.
  • cutoff--where a river erodes through a meander neck so that water flows both around the bend and past it.
  • delta--a level, fan-shaped accumulation of sediment where a stream empties into a quiet body of water, resulting in the building out of the shoreline.
  • dendritic drainage pattern--tributaries flow into the main stream in a pattern similar to the branches of a tree.
  • depression--area completely surrounded by higher elevation.
  • deranged drainage pattern--irregular and unconnected streams randomly flowing in all directions, the result of recent disturbance such as glaciation.
  • differential erosion--resistant rocks withstand the erosion processes longer than non-resistant rocks and thus the resistant rocks tend to form higher topographic features than neighboring non-resistant rocks.
  • dike--steep-dipped intrusion of magma into a fracture in the bedrock.
  • dip--the angle formed by a horizontal plane and a rock layer; the direction in which a rock layer extends further underground.
  • disappearing stream--stream which flows into a cavern.
  • distributary--an out-flowing branch of a stream that does not rejoin it, characteristically occurs on a delta or alluvial fan.
  • divide--high land separating water which will flow into one stream from that which will flow into another.
  • dome--oval or circular upfold of rock layers.
  • drainage basin--geometrical pattern formed by a stream network as depicted on a map.
  • drainage pattern--geometrical pattern formed by a stream network or system as depicted on a map.
  • drift--material transported and deposited by a glacier, the meltwater, or winds over glaciated deposits.
  • drumlin--an elongated oval shaped hill deposited by a glacier which indicates the direction of movement of the ice.
  • end moraine--glacial deposit of till at a glacier's end, either a terminal or recessional moraine.
  • entrenched--due to uplift or rejuvenation, a stream deepens its channel.
  • entrenched meanders--stream bends incised into the bedrock indicating a rejuvenated life cycle.
  • erosion--process of breaking up and removing rock materials by such agents or forces as running water, gravity, wind, glaciers, ground water, and waves.
  • escarpment--a cliff or steep slope.
  • esker--a long, narrow remnant ridge of sand and gravel which was in the bed of a stream on, under, or inside a glacier.
  • exotic stream--stream which heads in a humid environment but flows through a desert, like the Nile and the Colorado
  • estuary--a flooded stream mouth that experiences tides.
  • extrusive igneous body--unit of igneous rock at or near the earth's surface.
  • fault--a break in the rock along which movement has occurred.
  • fault trace--the line formed by the intersection of a fault plane with the horizontal surface.
  • fissure--crack in the earth's crust from which lava flows.
  • floodplain--portion of a stream valley bordering the channel, built up of sediments brought there by the stream during times of flood.
  • finger lake--a long, narrow trough lake often formed behind terminal or recessional moraines.
  • fiord (fjord)--an ocean flooded glacial trough.
  • glacier--mass of ice, formed on land from recrystallized snow, that moves under the pull or gravity and the weight of the overlying snow.
  • graben--down-faulted block between two faults.
  • graded stream--a stream which has a gradient that is just steep enough for the stream to transport its load.
  • gradient--slope of a stream bed, usually expressed in feet per mile, calculated by the difference in elevation in feet divided by the distance along the stream in miles, the rise over the run.
  • groin--a man-made projection extending roughly perpendicular from the shoreline.
  • ground moraine--the blanket of material deposited over the landscape as a glacier melts.
  • hammock--tree islands in a marsh area.
  • hanging trough--tributary glacial valley in which the floor is notably higher than the floor of the main glacial valley.
  • hanging valley--tributary stream valley in which the floor is notably higher than the floor of the glacial trough into which it leads.
  • haystack--a hill of soluble bedrock remaining after the neighboring materials have been eroded away.
  • head--noun--source or highest point of a stream; verb--forms, becomes a stream.
  • headland--land sticking out into the ocean, a promontory.
  • headward erosion--the extension of stream and gullies as they downcut and extend themselves toward their source.
  • headwaters--all of the tributaries near the head or source of a stream.
  • hogback--asymmetrical ridge formed by the dip-slope of a resistant rock layer.
  • hook--a type of spit with a bent end.
  • horizontal bedrock--solid crustal layers which do not have a significantly measurable dip or remain unfolded.
  • horn--sharp, pyramid-shaped peak formed by erosion by alpine glaciers on each side.
  • horst--an up-faulted block between two faults.
  • ice berg--a floating chunk of a glacier produced by calving or breaking off from the main glacier.
  • ice-contact stratified drift--glacial material which was deposited by meltwater and glacial ice acting together.
  • inselberg--remnant mountain surrounded by two coalescing pediments.
  • intermittent stream--stream that has a dry bed for part of the year.
  • intrusive igneous body--unit of igneous material within the earth.
  • jetty--a man-made projection from the shoreline which directs the flow of a stream seaward.
  • joint--a break in the rock along which no movement has occurred.
  • kame--cone-shaped hill formed by the deposition of the materials caught in a hole in a glacier.
  • karst--adjective to describe the topography developed by solution by ground water.
  • kettle--depression in an outwash plain or ground moraine formed by an ice block which became buried and melted.
  • klippe--a mass of rock resulting from overthrust faulting.
  • knob and kettle topography--a rough and irregular terrain resulting from glacial deposition.
  • laccolith--igneous intrusion that upwarps the horizontal layers between which it penetrates.
  • lagoon--a protected body of water along a coastline.
  • landslide--a mass movement of material downslope including bedrock chunks and finer material.
  • lateral moraine--moraine which builds up along the sides of a glacier and the resulting deposit.
  • lava flow--outpouring of magma onto the earth's surface from a volcanic vent or a fissure.
  • loess--wind-blown deposit of silt-sized particles, sometimes associated with glaciation.
  • longitudinal--a long sand dune formed parallel to the wind direction.
  • marine terrace--an uplifted wave-cut terrace or wave-built terrace.
  • marsh--a wetland area dominated by grasses.
  • meander--a winding or looping bend in a stream channel.
  • meander neck--the land separating the ends of a meander.
  • meander scar--the last remaining indication of a filled-in oxbow lake.
  • medial moraine--the joining of two lateral moraines where a tributary glacier joins the main glacier.
  • mesa--flat-topped plateau formed in an arid climate where a resistant horizontal layer protects the underlying layers.
  • meteor crater--depression formed by the impact of a projectile from space.
  • mine--man-made excavation of earth materials to obtain natural resources.
  • monadnock--a hill formed by differential erosion which exposes a more resistant intrusive igneous body.
  • moraine--glacial drift or till deposited chiefly by direct glacial action, the landform made of such material.
  • mountain--a high topographic feature resulting from volcanism, folding and differential erosion, or faulting.
  • mouth--the lowest part of a stream.
  • mudflow--a mass movement involving the mixture of surface debris and water such that it flows downslope.
  • mud torrent--a type of mudflow which contains pyroclastic materials and is BEST associated with volcanic eruptions.
  • natural levee--a long alluvial ridge built up on either side of a stream channel during flood stage.
  • obsequent stream--stream which flows in the opposite direction of the consequent stream or thus flows downslope to subsequent streams.
  • offshore bar--a sand bar which is not attached to the mainland but is parallel to it.
  • outwash plain--broad, stratified, gently sloping deposit formed beyond the terminal moraine or recessional moraine by streams carrying away the meltwater.
  • overthrust fault--very low angle reverse fault.
  • oxbow lake--a crescent-shaped lake formed in an abandoned stream bend by a meander neck being cut off and the ends filling in with alluvium.
  • oxbow swamp--oxbow lake that has filled in with sediment but still contains some water.
  • parallel drainage pattern--develops on a pronounced regional slope in one direction.
  • parabolic--hairpin-like sand dune with the horns pointing upwind.
  • paternoster lakes--series or chain of small, round trough lakes.
  • pediment--gently sloping erosional surface formed by the wearing back of a fault block in an arid climate
  • peneplain--flat landscape resulting from prolonged erosion of a region.
  • perennial stream--stream which contains water in its channel throughout the year.
  • piedmont glacier--glacier formed by one or more valley glaciers which extends beyond the mountain.
  • pingo--steep, round hill in an area of permafrost formed by around an ice core.
  • plateau--somewhat flat highland area.
  • playa--intermittent lake in an arid region which has no outlet.
  • promontory--headland, land jutting out from the coastline.
  • radial drainage pattern--pattern of stream flowing outward from a central point.
  • recessional moraine--a ridge-like accumulation of till deposited by a glacier along its outer margin, back from the position of its maximum advance.
  • rectangular drainage pattern--angular stream pattern developed on faulted or jointed bedrock.
  • reef--buildup of coral colony.
  • rejuvenated--returned to a previous stage of the erosional cycle of a stream due to uplifting of the head or lowering of the base level.
  • resequent stream--flows in the same direction as consequent stream, however, it forms at a later time and flows down a dip slope formed by erosion.
  • ridge--the line formed where the highest point along the slopes of a range of mountains or hills unite.
  • rock--a solid unit of the earth's crust composed of minerals, organic matter, rocks, and other junk.
  • sand bar--an accumulation of sand by wave action.
  • scarp--a cliff, short for escarpment.
  • sea arch--a remnant of a headland projecting into the sea, connected to the mainland above, but separated from the mainland at the water level.
  • sediment--finely divided mineral and organic matter derived from pre-existing rock and life processes.
  • shield cone--large, gently sloping volcanic cone composed of low-viscosity lava flows.
  • sill--intrusion of magma parallel with the rock layers.
  • sinkhole--a funnel-shaped depression in the surface that occurs where rocks such as salt, gypsum, limestone, dolomite, or marble have been dissolved and the roof of the solution cavern has collapsed.
  • slipoff slope--inside of a meander where deposition is occurring resulting in a gentle slope.
  • slump--a mass movement involving the slippage of material along a curved surface.
  • solifluction--a type of creep associated with areas of permafrost.
  • solution valley--lowland produced by cavern roof collapse along above a cavern.
  • spit--a sand bar extending across a bay or cove but attached only at one end.
  • spring--discharge of ground water.
  • stack--the remains of a sea arch when the top connection to the mainland has collapsed.
  • stalactite--the deposit hanging from the roof of a cavern as ground water emerges, evaporates, and leaves its dissolved materials.
  • stalagmite--the deposit sticking up from the floor of a cavern as ground water drips from the ceiling to the floor, evaporates, and leaves its dissolved materials.
  • stock--igneous intrusion similar to a batholith, but smaller.
  • stream--any appreciable flow of water in a channel, the flow is always DOWN which may be in any direction on a map.
  • stream piracy or stream capture--the diversion of the headwaters of a stream by a stream with a steep gradient extending itself headwards through the divide.
  • stream system--a main stream and all of its tributaries.
  • strike--the direction formed by the intersection of a rock layer and a horizontal plane; the strike direction is perpendicular to the dip direction.
  • subsequent stream--a stream which flows along the non-resistant bedrock in an area of eroded folds.
  • superimposed stream--stream which has downcut or incised itself into rocks of different age and resistance than the original rocks upon which it formed.
  • swamp--a wetland dominated by trees.
  • syncline--downfold of rock layers.
  • talus--accumulation of rock debris at the base of a cliff.
  • talus cone--circular pile of rock debris at the base of a cliff.
  • tarn--a small mountain lake in the bottom of a cirque.
  • terminal moraine--a rugged ridge or belt of till at the farthest advance of a glacier.
  • terrace--remnant of a valley floor before rejuvenation of a stream, remainder of part of an old floodplain at a higher level than the present one, indicates rejuvenation has occurred.
  • till--unstratified material deposited by a glacier, the result of direct deposition by the ice; all till is drift but not all drift is till.
  • till plain--generally flat region of morainal deposits.
  • tombolo--a sand bar which connects an island to the mainland.
  • transverse--a sand dune with the gentle slope on the windward side and a ridge perpendicular to the wind direction.
  • trellis drainage pattern--long parallel stream with short tributary streams at right angles developing on folded strata.
  • triangular facets--triangle shapes formed on face of fault scarp by erosion best seen on fault block mountains in the early erosional stage.
  • tributary--a stream which joins the main stream, applies to glaciers also.
  • trough--U-shaped valley of a glacier.
  • trough lake--lake which forms in a U-shaped glacial valley.
  • U-shaped valley--shape of a glacially eroded valley OR the valley of mature and old age streams.
  • unconformity--gap in the rock record, boundary between two notably different age rocks.
  • undercut slope--steep slope cut by erosion on the outside of a meander.
  • valley glacier--when a cirque glacier grows larger and extends down the valley.
  • valley train--deposit of drift by a stream which partially fills the stream valley.
  • vent--hole in a volcano from which materials are ejected.
  • volcanic cone--cone shaped mound built up by volcanic eruptions.
  • volcano--conical, circular structure over a vent in the earth's crust.
  • volcanic neck--solidified igneous rock remaining after the erosion of an extinct volcano.
  • volcanic pipe--the feeder tube of a volcano.
  • volcanic plug--solidified lava filling the central vent of a volcano.
  • V-shaped valley--shape of a valley cut by a youthful steam or running water.
  • water gap--pass in a mountain ridge through which a stream flows.
  • watershed--a drainage basin, the land area drained by a stream.
  • wave-built terrace--the depositional slope seaward from a wave-cut terrace.
  • wave-cut cliff--the steep-sloped coast formed by waves eroding the shoreline.
  • wave-cut terrace--the erosional slope formed by the retreat of a wave-cut cliff.
  • wind gap--an abandoned water gap; a water gap which is no longer occupied by a stream because of stream piracy or stream capture.
  • yazoo stream--tributary stream which flows parallel to the main stream on its floodplain before joining it.
    Return to the Weathering and Mass Wasting Lecture Notes
    Return to the Ground Water Lecture Notes
    Return to the Fluvial Lecture Notes
    Return to the Arid and Eolian Lecture Notes
    Return to the Glaciation Lecture Notes
    Return to the Waves Lecture Notes


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