Blue Crab Glossary - glossary of terms & names refering to the Maryland Blue Crab

Beach-Net!'s Ocean Glossary

This glossary of ocean terms defines words and phrases you may have heard but don't quite understand.


May be either natural or artifical. Natural accretion is the buildup of land, solely by the action of the forces of nature, on a beach by deposition of water-borne or airborne material. Artificial accretion is a similar buildup of land by reason of an act of man, such as the accretion formed by a groin, breakwater, or beach fill deposited by mechanical means.


Parallel to and near the shoreline. Same as longshore.


Flood zone subject to still-water flooding during storms that have a 100-year recurrence interval.

Backbarrier Flats

Low-lying sandy regions on the landward side of the sand dunes. Often covered with salt-tolerant grasses and shrubs.

Backbarrier Marsh

Marsh formed behind a coastal barrier, often containing significant coarse sediment that has washed in from the seaward side.


The seaward return of water following the uprush of the waves. For any given tide stage, the point of farthest return seaward of the backrush is known as the limit of backrush.


That zone of shore or beach lying between the foreshore and the dunes and acted upon by waves only during severe storms, especially when combined with exceptionally high water. It includes the berm or groins.


A submerged or emerged mound of sand, gravel or shell material built on the ocean floor in shallow water by waves and currents.

Barrier Beach

A sedimentary land-form essentially parallel to the shore, the crest of which is above normal high water level. Also called a barrier island.

Barrier Island

A barrier beach that is unconnected to the mainland.

Barrier Lagoon

A bay roughly parallel to the coast and separated from the open ocean by barrier islands or spits.

Barrier Spit

A barrier beach that is connected to land at one end with the other end extending into a body of water such as a bay, lagoon or ocean.


A recess in the shore or an inlet of a sea between two capes or headlands, not as large as a gulf but larger than a cove.


A zone of unconsolidated material that extends landward from the low water line to the place where there is marked change in material or physiographic form, or to the line of permanent vegetation (usually the effective limit of storm waves).

Beach Erosion

The carrying away of beach materials by wave action, tidal currents, littoral currents or wind.

Beach Face

The section of the beach normally exposed to the action of wave uprush. The foreshore of a beach.


In a barrier beach system, the relatively flat, sandy area between the berm crest and the dunes formed by the deposit of material by wave action. Some beaches have no berm, others have one or several.

Berm Crest

The seaward limit of a berm.


A linear, floating or mound-like coastal engineering structure constructed offshore parallel to the shoreline to proteft a shoreline, harbor or anchorage from storm waves.

Bypassing Sand

Hydraulic or mechanical movement of sand, from an area of accretion to a downdrift area of erosion, across a barrier to natural sand transport such as an inlet or harbor entrance. The hydraulic movement may include natural movement as well as movement caused by man.

Current, Littoral

Any current in the littoral zone caused primarily by wave action, i.e., longshore currrent, rip current.

Current, Longshore

The littoral current in the breaker zone that moves essentially parallel to the shore, usually generated by waves breaking at an angle to the shoreline.


Scallop-like ridges and depressions in the sand spaced at regular intervals along the beach.


In the direction of the predominant movement of sediment along the shore. The side of a groin, jetty or other structure which is deprived of sand.


The removal of sediment or the excavation of tidal or subtidal bottom to provide sufficient depths for navigation or anchorage, or to obtain material for construction or for beach nourishment.


Any natural hill, mound or ridge of sediment landward of a coastal berm deposited by the wind or by storm overwash. Sediment deposited by artificial means and serving the purpose of storm-damage prevention and flood control.

Ebb Tide

The period of tide between high water and low water. A falling tide.


The wearing away of land by the action of natural forces. On a beach, the carrying away of beach material by wave action, tidal currents, littoral currents, or wind.


The part of a river that is affected by tides. The region near a river mouth in which the freshwater of the river mixes with the saltwater of the sea.


Pertaining to an estuary.


The distance over water in which waves are generated by a wind having a rather constant direction and speed.

Flood Tide

The period of tide between low water and high water. A rising tide.


The front dune immediately behind the backshore.


The steeper part of the beach that extends from the low water mark to the upper limit of high tide. The beach face.


A narrow, elongated coastal-engineering structure built on the beach perpendicular to the trend of the beach. Its purpose is to trap longshore drift to build up a section of beach.


An area of high elevation more resistant to erosion than surrounding areas and less susceptible to flooding. Headlands can supply sand and gravel to beaches.

High Tide

The maximum elevation reached by each rising tide.


An intense tropical cyclone with winds that move counterclockwise around a low-pressure system. Maximum sustained winds of 74 miles per hour or greater.


A narrow, elongated coastal-engineering structure built perpendicular to the shoreline at inlets. Designed to prevent longshore drift from filling the inlet and to provide protection for navigation.


A shallow body of water, as a pond or lake, usually connected to the sea.

Littoral Drift

The sedimentary material moved in the littoral zone under the influence of waves and currents.

Littoral Transport

The movement of littoral drift in the littoral zone by waves and currents. Includes movement parallel (longshore transport) and perpendicular (on/offshore transport) to the shore.

Littoral Zone

In beach terminology, an indefinite zone extending seaward from the shoreline to just beyond the breaker zone.

Low Tide

The minimum elevation reached by each falling tide.


An area of soft, wet or periodically inundated land, generally treeless and usually characterized by grasses and other low growth.

Mean High Water

The average height of all of the high waters recorded at a given place over a 19-year period.

Mean Low Water

The average height of all of the low waters recorded at a given place over a 19-year period.

Mean Sea Level

The average height of the surface of the sea at a given place for all stages of the tide over a 19-year period.

Neap Tide

A tide occurring near the time of quadrature of the moon with the sun. The neap tide range is usually 10- to 30-percent less than the mean tidal range.


On the U.S. East Coast, a storm (low-pressure system) whose counterclockwise winds approach the shore from the northeast as the storm passes an area. Its steeper waves approaching from the opposite direction to normal lower waves can cause coastal erosion.


The placement of sediment on a beach or dunes by mechanical means.


The uprush and overtopping of a coastal dune by storm waters. Sediment is usually carried with the overwashing water and deposited, usually in a fan shape, on the landward side of the dune or barrier.


A layer, facing, or protective mound of stones randomly placed to prevent erosion, scour or sloughing of a structure or embankment. Also the stone so used.


An apron-like, sloped, coastal-engineering structure built on a dune face or fronting a seawall. Designed to dissipate the force of storm waves and prevent undermining of a seawall, dune or placed fill.

Salt Marsh

A marsh periodically flooded by salt water.


An almost vertical slope along the beach caused by erosion by wave action. It may vary in height from a few inches to several feet, depending on wave action and the nature and composition of the beach.


A vertical, wall-like coastal-engineering structure built parallel to the beach or duneline and usually located at the back of the beach or the seaward edge of the dune.


Solid particles or masses of particles that originate from the weathering of rocks and are transported, suspended in, or deposited by air, water or ice, or by other natural agents such as chemical precipitation and organic secretion.

Spring Tide

A tide that occurs at or near the time of new or full moon (syzygy) and that rises highest and falls lowest from the mean sea level.

Surf Zone

The area between the outermost breaker and the limit of wave uprush.


The periodic rising and falling of the water that results from gravitational attraction of the moon, the sun and other astronomical bodies acting upon the rotating earth.


The direction opposite that of the predominant movement of sediment along the shore. The side of a groin, jetty or other structure where sand accumulates.


A general term for land or ground that is higher than the floodplain.


The landward flow of water up onto the beach that occurs when a wave breaks.

Velocity Zone (V-Zone)

A zone subject to velocity-water flooding during storms that have a 100-year recurrence interval. In coastal areas the V-Zone generally extneds inland to the point where the 100-year flood depth is insufficient to support a 3-foot high breaking wave.


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