glossary

Accretion                                                
Natural accretion is the buildup of land on a beach, solely by the action of the forces of nature, through deposition of material brought by air or by water. Artificial accretion is a similar buildup of land by reason of an act of man, such as the accretion formed by a groin or breakwater or that formed when beach fill is deposited by mechanical means.

Anthropogenic
Human-influenced impacts on the natural world such as the effects of sheep grazing on plant succession, the impacts of erosion-control structures, and the results of endangered-species-protection laws.

Beach nourishment 
The process of using mechanical or hydraulic means to replenish a beach or dune with material (usually sand) obtained from another location.

Berm
An upper part of the beach that is nearly horizontal or that slopes away from the ocean.

Biomass
A general term referring to the volume of living things in a given area; biomass is measured in weight per unit of area.

 Coastal bank
The seaward face or side of any elevated landform, other than a coastal dune, that lies at the landward edge of a coastal beach, of land subject to tidal action, or of other wetland. Coastal banks are a Resource Area protected by the Massachusetts Wetlands Protection Act and Regulations (See 310 Code of Mass. Regulations 10.30) and may contribute significantly to storm-damage prevention or to flood control, acting as a vertical buffer or as a sediment source for beaches, dunes or barriers. A coastal bank differs from a coastal dune in that a coastal bank was deposited by a glacier.

Cobble                                                     
Rocks generally around three inches in diameter  -- larger than pebbles and gravel but smaller than boulders. Cobble is found in scattered clumps in 15 to 20 foot water out to about 1,200 feet off the eastern shore of Nantucket from about a half-mile north to a half-mile south of Sankaty Head Lighthouse. This cobble is a breeding ground for food that striped bass love to eat, including crabs, sand eels, sand dabs and juvenile lobster. Strong tidal currents wash schools of squid through this area, and winter and yellow flounder breed there.

Coir
Coconut fiber. Coir is used in making giant, elongated bags that are filled with sand and are designed to protect the land behind them and to act as a source of sediment.

ConCom
Nantucket term for the Nantucket Conservation Commission.

DEP
The acronym for Massachusetts Department of Environmental Protection, also called MassDEP. DEP is the state agency responsible for ensuring clean air and water, the safe management of toxics and hazards, the recycling of solid and hazardous wastes, the timely cleanup of hazardous-waste sites and spills, and the preservation of wetlands and coastal resources.

Dewatering
The pumping of water from beaches right after waves break via a system of perforated pipes buried in the beach. Dewatering is designed to move the water back out to sea while leaving the sand brought in by that water, thus building the beach outward.

Downdrift
In the direction of the predominant movement of sediment along the shore.

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

Ebb tide
The outgoing tide.

Erosion                                                          
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 by deflation.

Extirpate
Completely exterminate a species from a given region or area.

Fetch
Distance of open water over which the wind blows in the development of waves. The fetch length can restrict wave development so that only relatively small waves occur in narrow bays and lagoons. Fetch can be affected by shoals and reefs between wind sources and the areas where the waves break.

Floodplain
The area of shorelands extending inland from the normal yearly maximum stormwater level to the highest expected stormwater level in a given period of time (e.g. 5, 50, 100 years).

Flood tide
The incoming tide.

Foredune
The first dune or dune ridge landward of the beach.

Gabion
A rock-filled wire basket. Groupings of gabions are sometimes used in attempts to protect ocean-side properties from erosion.

Geotube 
Elongated cloth bags or tubes made out of plastic material that are filled with sand. Geotubes can be stacked or arranged as a form of semi-hard coastal engineering.

Great salt pond                                               
As determined by the Commonwealth of Massachusetts, a salt or brackish pond 20 acres or larger.

Groin 
A narrow elongated coastal-engineering structure constructed on the beach perpendicular to the trend of the beach. The intended purpose of a groin is to trap longshore drift, building up a section of beach.

Hard armor
A term used to describe any coastal-erosion-control structure built of stone, concrete, brick, wood or metal.

High-water line 
The intersection of the plane of mean high water with the shore; the highest elevation on the shore reached during a storm or rising tide.

Intertidal zone (littoral zone)
Generally considered to be the zone between mean high-water and mean low-water levels.

Jetty
A coastal-engineering structure constructed at an inlet perpendicular to the shoreline and designed to prevent longshore drift from filling the inlet and to provide protection for navigation.

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

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

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.

Order of conditions (OOC)                                                                                                                   
When the Conservation Commission rules in the positive, it issues an order of conditions -- in effect, an approval of a given project with a set of conditions to which the proponent must adhere for the approval to stand.

Passive erosion
The eventual migration of a shoreline landward beyond an installed hard structure such as a bulkhead or rock revetment. The result is the gradual loss of beach in front of the bulkhead or revetment as the water deepens and the shoreface moves landward.

Revetment
Facing of stone, concrete, or rubble built to protect an embankment or upland against erosion by wave action or currents.

Rosa Rugosa                                     
Commonly called saltspray rose, this species of rose was imported to Nantucket from Asia during Nantucket’s whaling era. Rosa rugosa is popular on Nantucket today not only for its beautiful, fragrant, pink and white flowers but also for its ability to hold coastal soils and sediments in place.

Sand
Loose material that consists of grains of rock ranging between 0.0625 and 2.0 millimeters in diameter.

Scour
Removal of underwater material by waves and currents, especially at the base or toe of a shore structure.

Seawall 
A vertical wall-like coastal-engineering structure constructed parallel to the beach and usually located at the base of a coastal bank.

Sediment                                                   
Solid particles of organic or inorganic material that come from the weathering of rock and are carried and deposited by wind, water, or ice.

Source sediment impoundment
When a revetment is constructed against a coastal bank or bluff, over time the flow of sand to downstream shorelines or to untreated beaches is choked off because the rock wall prevents the ocean from eroding sediments from the bank, bluff, or dune and moving them down the shoreline.

Terracing                                                   
Coir-fiber sand-filled logs stepping up a bluff face from the beach intended to stabilize slumping sections of the face.

Turbidity                                                     
A measure of water clarity based on the amount of particulate matter (such as sediments) in a body of water.

Updrift                                                       
The direction opposite that of the predominant movement of sediment along the shore.

Watershed
An area of land from which groundwater drains into a harbor, ocean, bay, pond, lake, river, or stream.

Wetland                                                     
Area of land with saturated or nearly saturated soils most of the year. Wetlands serve as interfaces between land-based and water-based environments.

Wrack line                                                      
A line generally defining the landward limit of high tide or storm-wave uprush; the wrack line typically consists of seaweed, shells, and organisms that have died.

This glossary contains a subset of a glossary prepared by Peter Brace in which he used definitions gleaned from www.answers.com, Webster’s Ninth New Collegiate Dictionary, Webster’s Encyclopedic Unabridged Dictionary of the English Language, Encarta World English Dictionary, “Nantucket: A Natural History” by Peter B. Brace, Beachopedia; http://www.beachapedia.org/Main_Page, and the Massachusetts Office of Coastal Zone Management’s Web site, specifically; “Guidelines for Barrier Beach Management in Massachusetts. February 1994”.