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85 Cards in this Set
- Front
- Back
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A lava flow with a rubbly surface
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a'a'
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A volcano that has erupted within the past few centuries and will likely erupt again
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Active Volcano
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A large circular depression with steep walls and a fairly flat floor, formed after an eruption as the center of the volcano collapses into the drained magma chamber below
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Caldera
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A subaerial volcano consisting of a cone-shaped pile of tephra whose slope approaches the angle of repose for tephra
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Cinder Cone
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A type of fracturing that yields roughly hexagonal columns of basalt; columnar joints form when a dike, sill, or lava flow cools
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Columnar Jointing
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A circular depression at the top of a volcanic mound; a depression formed by the impact of a meteorite
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Crater
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A volcano that has not erupted for hundreds to thousands of years but does have the potential to erupt again in the future
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Dormant Volcano
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An eruption that yields mostly lava, not ash
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Effusive Eruption
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Violent volcanic eruptions that produce clouds and avalanches of pyroclastic debris
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Explosive Eruption
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A volcano that was active in the past but has now shut off entirely and will not erupt in the future
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Extinct Volcano
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A conduit in a magma chamber in the shape of a long crack through which magma rises and erupts at the surface
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Fissure
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Vast sheets of basalt that spread from a volcanic vent over an extensive surface of land; they may form where a rift develops above a continential hot spot, and where lava is particularly hot and has low viscosity
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Flood Basalt
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A thick slurry formed when vlocanic ash and debris mix with water, either in rivers or from rain or melting snow and ice on the flank of a volcano
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Lahar
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Molten rock that has flowed out onto the Earth's surface
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Lava
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Sheets or mounds of lava that flow onto the ground surface or sea floor in molten form and then solidify
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Lava Flow
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A space below ground filled with magma
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Magma Chamber
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A lava flow with a surface texture of smooth, glassy, rope-like ridges
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Pahoehoe
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Fragmented material that sprayed out of a volcano and landed on the ground or sea floor in solid form
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Pyroclastic Debris
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A fast-moving avalanche that occurs when hot volcanic ash and debris with air and flow down the side of a volcano
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Pyroclastic Flow
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A subaerial volcano witha broad, gentle dome, formed either from low viscosity basaltic lava or from large pyroclastic sheets
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Shield Volcano
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A large, cone-shaped subaerial volcano consisting of alternating layers of lava and tephra
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Stratovolcano
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Unconsolidated accumulations of pyroclastic grains
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Tephra
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A pyroclastic igneous rock composed of volcanic ash and fragmented pumice, formed when accumulations of the debris cement together
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Tuff
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Open holes in igneous rock formed by the preservation of bubbles in magma as the magma cools into solid rock
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Vesicles
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Tiny glass shards formed when a fine spray of exploded lava freezes instantly upon contact with the atmosphere
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Volcanic Ash
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A vent from which melt from inside the Earth spews out onto the planet's surface; a mountain formed by the accumulation of extrusive volcanic rock
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Volcano
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The angle of the steepest slope that a pile of uncemented material can attain without collapsing from the pull of gravity
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Angle of Repose
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A turbluent cloud of debris mixed with air that rushes down a steep hill slope at high velcoity; the debris can be rock and/or snow
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Avalanche
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The gradual downslope movement of regolith
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Creep
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a specific type of creep, found in tundra regions (cold, treeless) regions
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Solifluction
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A downslope movement of mud mixed with larger rick fragments
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Debris Flow
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A sudden downslope movement of material consisting only of regolith
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Debris Slide
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The surface on which the slump slips along a sppon-shaped sliding surface and slips semicoherently downslope
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Failure Surface
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The distinct step along the upslope edge of a slump where the regolith detached
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Head Scarp
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A sudden movement of rock and debris down a non-vertical slope
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Landslide
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when wet sediment by destroying the cohesion between the grains; shaking
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Liquefaction
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The gravitationally caused downslope transport of rock, regolith, snow, or ice
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Mass Movement (Mass Wasting)
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A downslope movement of mud at slow to moderate speed
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Mudflow
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A natural feature of the environment that can cause damage to living organisms and to buildings
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Natural Hazard
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Occur when a mass free-falls from a steep (vertical) cliff
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Rock Fall (Debris Fall)
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A sudden downslope movement of rock
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Rock Slide
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A sloping apron of fallen rock along the base of a cliff
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Talus
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Excavation at the base of a slope that results in the formation of an overhang
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Undercutting
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A gently sloping apron of sediment dropped by an ephemeral stream at the base of a moutain in arid or semi-arid regions
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Alluvial Fan
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Sorted sediment deposited by a stream
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Alluvium
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Indicates the likelihood that a flood of a given size or larger will happen at a specified locality durig any given year
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Annual Probability
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A stream that cuts across an uplifted maountain range; the stream must have existed before the range uplifted and must then have been able to downcut as fast as the land was rising
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Antecedent Stream
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A sheet or elongated lens or mound of alluvium; a unit of air-pressure measurement approximately equal to 1 atm
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Bar
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The lowest elevation a stream channel's floor can reach at a given locality
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Base Level
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A sediment choked stream consisting of entwined subchannels
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Braided Stream
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The total quantity of sediment a stream can carry
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Capacity
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A trough dug into the ground surface by flowing water
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Channel
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The maximum particle size a stream carries
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Competence
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A wedge of sediment formed at a river mouth when the running water of the stream enters standing water, the current slows, the stream loses competence, and sediment settles out
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Delta
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The volume of water in a condiut or channel passing a point in one second
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Discharge
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The fan of small streams formed where a river spreads out over its delta
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Distributary
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The process in which water flowing through a channel cuts into the substrate and deepens the channel relative to its surroundings
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Downcutting
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A highland or ridge that seprates one watershed from another
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Drainage Divide
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An array of interconnecting streams that together drain an area
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Drainage Network (Basin)
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A stream whose bed lies above the water table, so that the stream flows only when the rate at which water enters the stream from rainfall or melt-water exceeds the rate at which water infiltrates the ground below
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Ephemeral (Intermittent) Stream
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A flood that occurs during unusually intense rainfall or as the result of a dam collapse, during which the floodwater rise very fast
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Flash Flood
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A event during which the volume of water in a stream becomes so great that it covers areas outside the stream's normal channel
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Flood
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The flat land on either side of a stream that becomes covered with water during a flood
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Floodplain
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The process by which a stream channel lengthens up its slope as the flow of water increases
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Headward Erosion
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A cross-sectional image showing the cariation in elevation along the length of the river
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Longitudinal Profile
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A snake-like curve along a stream's course
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Meander
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A pair of low ridges that appear on either side of a stream and develop as a result of the accumulation of sediment deposited naturally during flooding
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Natural Levee
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A stream that flows year-round becuase its bed lies below the water table, or because more water is supplied from upstream that can infiltrate the ground
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Permanent Stream
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The average time between successive geologic events
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Recurrence Interval
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Floods that appear almost every year during seasons when rainfall is heavy or when winter snows start to melt
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Seasonal Flood
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A film of water less than a few mm thick that covers the ground surface during heavy rains
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Sheetwash
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The situation in which headwater erosion causes one stream to intersect the course of another, previously independent stream, so that the intersectd stream starts to flow down the channel of the first stream
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Stream Piracy (Capture)
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The renewed downcutting of a stream into a floodplain or peneplain, caused by a relative drop of the base level
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Stream Rejuvenation
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Created from the stream's base level drops again and/or the discharge increases, the stream will start to cut down into its own alluvium, bordering the flood plain
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Stream Terrace
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A ribbon of water that flows in a channel
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Stream
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A stream whose geometry has been laid down n a rock structure and is not controlled by the structure
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Superposed Stream
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Side channel that merge with the main channel, because once a channel forms, the surrounding land slopes into it
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Tibutary
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The region that collects water that feeds into a given drainage network
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Watershed
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Sediment or rock that transmits water easily
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Aquifer
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Sediment or rock that does not transmit water easily and therefore retards the motion of water
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Aquitard
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A well in which water rises on its own
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Artesian Well
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The downward pointing, cone-shaped surface of the water table in a location where the water table is experiencing drawdown because of pumping at a well
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Cone of Depression
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A mathematical equation stating that a volume of water, passing throught a specified area of material at a given time, depends on the material's permability and hydraulic gradient
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Darcy's Law
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A location where groundwate flows back up to the surface, and may emerge at springs
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Discharge Area
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A region of current or recent volcanism in which magma or very hot rock heats up groundwater, which may discharge at the surface in the form of hot springs and or geysers
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Geothermal Region
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