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U.S. Geological Survey Open-File Report 2008-1206

Coastal Change Along the Shore of Northeastern South Carolina: The South Carolina Coastal Erosion Study

Glossary of Terms

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acoustics – The study of sound, particularly the generation, propagation, and reception of mechanical waves and vibrations.

backscatter – The scattering of acoustic energy back to a sonar receiver.

bathymetry – The measurement of ocean depths (seafloor topography).

barrier island – An elongated sandy island that lies roughly parallel to the mainland shore.

beachrock – Partially-cemented sedimentary rock formed in the intertidal zone that consists of sandy sediment and shell fragments.

berm – A sandy, nearly horizontal step-like feature on the backshore of a beach.

coastal compartment – A geographically defined segment of coastline in which sediment gains and losses are estimated for the purpose of calculating sediment budgets.

coastal plain – The relatively flat, low-lying physiographic province that extends landward of the shoreline to the Piedmont physiographic province along the U.S. Atlantic Margin.

continental crust – The solid, outermost layer or shell of the Earth that underlies the continents and continental shelves.

continental margin – The ocean floor that is between the shoreline and the abyssal floor, including the continental shelf, slope, and rise.

continental shelf – The submerged, gently sloping portion of the continental margin that extends seaward of the shoreline to the continental slope.

dip – The angular tilt or incline of a geologic feature or units.

dune – A low mound, ridge, or hill composed of wind-blown sediment.

escarpment - A relatively straight, cliff-like face or steep slope of considerable linear extent formed by faulting or erosion.

estuary – A water body located at the intersection of a river or stream with the sea, where freshwater mixes with saltwater and tidal effects are evident.

fault – A fracture or zone of fractures within rocks that show evidence of relative movement.

fluvial – Refers to rivers and streams.

geographic information system (GIS) – A computer-based system for capturing, storing, analyzing, managing and presenting geospatial data.

geologic framework – Refers to the underlying geologic setting, structure, and lithology (rock/sediment type) in a given area.

geomorphology – The study of landforms and the processes that create them.

ground-penetrating radar (GPR) – A geophysical method that uses pulses of electromagnetic energy to image the subsurface.

hardbottom – rocky areas of seafloor with little to no sediment cover.

hiatus – A break or interruption in the continuity of the geologic record, such as the time interval not represented by rocks or sediments along an unconformity.

highstand – The uppermost topographic position or elevation on land reached by sea level during a specific period in time.

insonify – To illuminate an area of the seafloor with sound energy, as with a sonar.

light detection and ranging (LIDAR) – A method of topographic surveying, generally from aircraft, that uses pulses of laser light.

longshore current – A shore-parallel current formed by breaking waves that approach the coast at an angle.

longshore transport – The movement of sediment parallel to the shoreline, driven by longshore currents.

mainland-attached beach - A beach that is backed by dry land; not separated from the mainland by a open body of water.

microtidal - Tidal range of less than 2 m (6.6 ft).

nearshore marine – The portion of the inner continental shelf that extends from the shoreline to water depths of about 10 m (30 ft).

paleochannel – An ancient incision that was cut by a stream or river and filled by younger sediments.

profile of equilibrium - A theoretical term that that describes a generally concave-up surface formed by waves breaking across a bed of uniform, unconsolidated sediment.

rift – A long, narrow zone where the Earth’s crust and lithosphere are being pulled apart.

salt marsh – Vegetated intertidal wetlands that occur in protected environments, such as behind barrier islands.

scarp – abbreviated form of escarpment.

seawall - An artificial structure built along a coast to protect buildings and infrastructure from coastal erosion, often resulting in loss of the dry beach.

sediment budget – An inventory or accounting of the inputs (gains), outputs (losses), and storage of sediment within a coastal compartment.

sedimentary rock – One of three main groups of rock that generally form by the cementation of layered deposits of sediment, including limestone, sandstone, conglomerate, and shale.

shoal – A submerged ridge, bank, or bar consisting of or covered by sandy, unconsolidated sediment that stands in relief on the seafloor.

shoreface – The narrow, shallow part of the inner continental shelf adjacent to shore in which waves regularly agitate the bottom.

sonar – Acronym for SOund Navigation And Ranging. A method that uses sound waves to detect the presence and location of submerged objects.

spit – A small point, low tongue, or narrow embankment of land that extends from the mainland or an island which is composed of sand deposited by alongshore sediment transport.

storm surge - An abnormal, sudden rise in sea level along the coast generated by large waves and low atmospheric pressure that accompany a storm at landfall.

swash - Flat, gently sloping areas of beach over which waves uprush and backwash. In South Carolina, swashes are broad, low-relief channels that drain water from the upland across the beach.

subaerial erosion – Erosion by wind, rain, and other processes that operate in the open air or immediately adjacent to the land surface.

tectonics – A field of study within geology concerned with structures within the Earth's crust and the particular forces and movements that create them.

tidal inlet – An opening in the shoreline, such as between two barrier islands, that connects bays or lagoons to the open ocean and is maintained by tidal currents.

topographic sheet (T-Sheet) – Surveys of the topography of a land surface; typically depicts the mean high-water line, which is used to define historical shoreline positions.

topography - The general configuration of any part of the Earth's surface, including its relief and the position of natural and artificial features.

truncation – The eroding or beveling of the top of a geologic unit or landform.

two-way traveltime – the time it takes an outgoing acoustic (or radar) pulse to travel from the source to the target and back to the receiver.

unconformity – A substantial break or gap in the geologic record where a surface of erosion or nondeposition separates geologic units of different ages.

unconsolidated – loose sediment; particles not cemented together.


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