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Definitions GEO
Earth Science FInal Exam
Question | Answer |
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exfoliation | a weathering process resulting in fracture when concentric plates or shells split away from a main rock mass like the layers of an onion; frequently explained as a form of pressure-release fracturing, but many geologists consider it could result from hydr |
slump | a type of slide in which blocks of material slide downslope as a consolidated unit over an upward-concaved curved fracture in rock or regolith; trees on the slumping blocks tilt uphill. The uphill portion of the slump usually consists of several tilted sl |
abrasion | a mechanical weathering process that consists of the grinding and rounding of rock and mineral surfaces by friction and impact |
joints | is a break (fracture) of natural origin in the continuity of either a layer or body of rock that lacks any visible or measurable movement parallel to the surface (plane) of the fracture |
oxidation | a chemical weathering process in which a mineral decomposes when it reacts with |
dissolution | a chemical weathering process in which mineral or rock dissolves |
hogback | a long, narrow ridge or a series of hills with a narrow crest and steep slopes of nearly equal inclination on both flanks |
soil creep | is the slow downward progression of rock and soil down a low grade slope |
debris flow | is a moving mass of loose mud, sand, soil, rock, water and air that travels down a slope under the influence of gravity. |
dendritic pattern | develop in areas where the rock (or unconsolidated material) beneath the stream has no particular fabric or structure and can be eroded equally easily in all directions |
trellis pattern | A drainage pattern in which tributaries join at high angles, often approaching right angles, which is common in areas with rocks of different strengths and in areas with regular series of folds |
waterfall | area where flowing river water drops abruptly and nearly vertically |
pothole | cylindrical pit formed in the rocky channel of a turbulent stream. It is formed and enlarged by the abrading action of pebbles and cobbles that are carried by eddies, or circular water currents that move against the main current of a stream. |
bedload | the total mass of a stream's sediment load that is transported along the bottom or in intermittent contact with the bottom of the streambed |
braided channel | A stream consisting of multiple small, shallow channels that divide and recombine numerous times forming a pattern resembling the strands of a braid |
point bar | a deposit of sediment in the slower water on the inside of a meander |
cutbank | is the outside bank of a water channel (stream), which is continually undergoing erosion |
oxbow | a crescent shaped lake created where a meander loop is cut off from a stream and the ends of the meander become plugged with sediment |
delta | a fan shaped accumulation of sediment formed where a stream enters a lake or ocean |
horn | a sharp, pyramid-shaped rock summit where three or more cirques intersect near the summit |
arrete | a sharp narrow ridge of rock between adjacent valleys or between two criques, created when two alpine glaciers moved along opposite sides of the mountain ridge and eroded both sides |
cirque | a steep-walled, spoon-shaped depression eroded into a mountain peak by a glacier |
U shaped valley | a glacially eroded valley with a broad, characteristic u-shaped cross section |
fjord | a deep, narrow, glacially carved valley on a high-latitude seacoast that was later flooded by encroaching seas as the glaciers melted |
hanging valley | a small glacial valley lying high above the floor of the main valley |
terminal moraine | an end moraine that forms when a glacier is at its greatest advance before beginning to retreat |
esker | a long, snakelike ridge formed as the channel deposit of a stream that flowed within or beneath a melting glacier |
drumlin | elongate hills, usually occurring in clusters, formed when a glacier flows over and reshapes a mound of till or stratified drift |
outwash | sediment deposited by streams flowing from the terminus of a melting glacier |
transverse dune | a relatively long, straight dune with a gently sloping windward side and a steep lee face that is perpendicular to the prevailing wind; forms where sand is plentiful and evenly dispersed |
longitudinal dune | a long, symmetrical dune that forms as a result of two different wind directions with comparable magnitude |
saltation | jumping movement of sedimentary particles that are ejected off through impact by another particle & carried downstream by wind or water for some distance before falling back to the surface Most sand grains in desert environments move via saltation by wind |
slip face | the steep leeward side of a dune, typically at the angle of repose for loose sand so that sand flows or slips down the face, where it is deposited |
yardang | is a streamlined protuberance carved from bedrock or any consolidated or semi consolidated material by the dual action of wind abrasion by dust and sand, and deflation which is the removal of loose material by wind turbulence. |
alluvial fan | is a triangle-shaped deposit of gravel, sand, and even smaller pieces of sediment, such as silt |
bajada | a broad, gently sloping depositional surface formed by the merging of alluvial fans from closely spaced canyons and extending outward into a desert valley |
playa | the dry desert lake bed of a playa lake, playa lake is a temporary desert lake that dries up during the dry season |
evaporite | any sedimentary rock, as gypsum or rock salt, formed by precipitation from evaporating seawater. |
desert pavement | a continuous cover of closely packed gravel or cobble sized clasts left behind when wind erodes smaller particles such as silt and sand |
gyre | a circular or elliptical current in either water or air |
wave refraction | The process by which the direction of waves moving in shallow water at an angle to the submarine contours is altered. |
longshore current | a current generated when waves strike a shore at an angle, producing flow parallel and close to the coast. Some are capable of transporting sand for hundreds of kilometers along the coastline |
sea stack | a pillar or rock left when a sea arch collapses or when the inshore portion of a headland erodes faster than the tip |
spit | a small ridge of sand or gravel extending from a beach into a body of water |
tombolo | is a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar. Once attached, the island is then known as a tied island. |
beach cusp | are shoreline formations made up of various grades of sediment in an arc pattern |
overwash | is the flow of water and sediment over a coastal dune or beach crest during storm events |
tidal delta | is the sand bar or shoaling area left at the mouth of a river by the movement of bottom mud and sand by a diurnal tide and the currents that result from that tide. |
coral | species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. |