Chapter 10-11 Quiz
Fjord
Former glaciated valley now flooded with seawater, U-shaped estuaries typically have steep sides, rock bottoms, and underwater sills; The shallowest area of the estuary occurs at the mouth, where terminal glacial deposits or rock bars form sills that restrict water flow
Depositional shores
Gradually subsiding shore, barrier islands and sand deposits are common
Wintertime beach
Heavy wave activity (Backwash dominates, Sediment moved away from shore, Narrower beach, Flattened beach face), Longshore bars are present, stormy weather
Coastline
boundary between shore and coast
Halocline
caused by a strong, vertical salinity gradient within a body of water
Ocean beach
closest part of the island to the ocean, older peat deposits found here
Mangrove swamps
coastal wetlands in tropics
Spit
connects one end to the mainland and hooks into a bay at the other
Peat deposits
decaying organic matter
Berm
dry, gently sloping region
Beach
entire active area of a coast affected by waves
Coast
extends inland as far as ocean related features are found
Wave-cut bench
flat, wave-eroded surface
Sea stacks
form when the tops of sea arches erode away completely
Sea arches
form where sea caves in headlands erode all the way through
Nearshore
from low tide water line to where waves break at low tide
Barrier flat
grassy area that forms behind dunes
Low Latitudes
restricted circulation, very warm, may be isothermal
Tombolo
sand bar that connects an island to the mainland
High latitudes
sea ice, may be isothermal
Bay barrier
seals off a lagoon from the ocean
Longshore trough
separates longshore bar from the beach
Dune
stabilized by grasses; protect lagoon from strong storms
Middle latitudes
strong thermocline may develop
Shore
the zone that lies between the low tide line and the highest area on land affected by storm waves
Longshore current
transports sand along the beach
Longshore bar
underwater sand bar parallel to the coast
Lagoon
water between barrier island and mainland
Backwash
water drains back to the ocean
Swash
water rushes up the beach
Beach face
wet, sloping surface between berm and shoreline
Marine terrace
Bedrock uplift
Salt Marshes
Between 30 and 65 degrees latitude
Breakwaters
Built parallel to a shoreline, Designed to protect harbors from waves, Can cause excessive erosion, requiring dredging to keep area stable
Jetties
Built perpendicular to shore, Built in pairs, Built to protect harbor entrances
Groins
Built perpendicular to the beach (Often made of rip rap, or large blocky material), Traps sand upcoast, which can cause erosion downstream of the longshore current, May necessitate a groin field, or a series of groins built along a beach
Freshwater runoff
Can produce well-defined halocline
Wave refraction
Causes zigzag motion of water in surf zone
Law of the Sea
Coastal nations jurisdiction, Right of free passage for ships, Open ocean mining regulated by International Seabed Authority, United Nations arbitrates disputes
95%
Coastal waters support about _____ of the total biomass in the oceans
Salt wedge
Deep, high volume, Strong halocline
Highly stratified
Deep, relatively strong halocline
Slightly stratified
Deeper, Upper layer less salty; lower layer more salty, Estuarine circulation
Seawalls
Destructive to environment, Designed to armor coastline and protect human developments, One large storm can remove beach, Wave activity eventually undermines seawall structure; need continual repair or will collapse
Coastal wetlands
Ecosystems intermittently inundated with ocean water, Peat deposits and halophytic plants, Nurseries, feeding grounds for commercially important marine animals, Efficiently cleanse polluted water, Absorb water from coastal flooding, Protect shores from wave erosion, Have piles of climate information
Tectonic estuary
Faulted or folded downdropped area now flooded with ocean formed by subsidence or land cut off from the ocean by land movement associated with faulting, volcanoes, and landslides
U.S. Office of Wetland Protection
1986, Minimize loss of wetlands, Protect or restore wetlands
Exclusive Economic Zone (EEZ)
200 nautical miles (370 km) from land (mineral and fishing resources)
Coastal Waters
Adjacent to land (to edge of continental shelf), Influenced by river runoff, wind, tides, Salinity variable (Freshwater runoff, Winds, Mixing by tides, Temperature variable; seasonal changes, prevailing winds)
Bar-built estuary
Lagoon separated from ocean by sand bar or barrier island estuaries are semi-isolated from ocean waters by barrier beaches, islands, spits. Only narrow inlets allowing contact with the ocean waters
Summertime beach
Light wave activity (Wide, sandy berm, steep beach face, Swash dominates), Longshore bars not present, generally milder storms
Gulf Coast
Low tidal range, Generally low wave energy, Tectonically subsiding, Mississippi delta dominates (Locally sea level rises due to compaction of delta sediments), Average rate of erosion is 1.8 meters (6 feet) per year
Longshore transport
Millions of tons of sediment moved yearly, Direction of transport changes due to wave approach, In general, net sediment movement is southward along the Atlantic and Pacific coasts of the United States
Atlantic Coast
Most coasts open to storm wave attack, Barrier islands common from Massachusetts south, Bedrock (Florida is made from Limestone), Strong storms called nor'easters can damage the coast north of Cape Hatteras, NC., Nor'easters can generate storm waves up to 6 meters (20 feet), Drowned river valleys common, erosion 0.8 meters/yr (2.6 feet)
Relocation
Move structures rather than protect them in areas of erosion
Longshore Current
Parallel motion of water along shoreline, Caused by wave refraction, Longshore currents travel at speeds up to 4 km (2.5 miles) per hour, Also called longshore drift, beach drift, or littoral drift, Only occurs in the shallow water surf zone, "rivers of sand"
Estuaries
Partly enclosed body of water, Freshwater runoff dilutes ocean water, 4 types; coastal plain, tectonic, bar-built, and fjord
Headland
Protruding bits of land absorb much wave energy
Beach replenishment
Sand added to beach/longshore current, Expensive; costs between $5 and $10 per cubic yard, Sand must be dredged from elsewhere
Vertically mixed
Shallow, low volume
Construction restrictions
Simplest alternative to hard stabilization, Limit building near shorelines
Hard stabilization
Structures built to decrease coastal erosion and interfere with sand movement, Also called armoring of the shore (some structures may increase erosion)
Pacific Coast
Tectonically rising, Experiencing less erosion than Atlantic or Gulf coasts, Open exposure to high energy waves, Average rate of erosion 0.005 meters (0.016 feet) per year
Coastal plain estuary
Well-developed drowned river valleys are generally found on coastlines with low, wide coastal plains Ex: Hudson River, Chesapeake Bay, and Delaware Bay
Mixing by tides
Water may be isohaline
Erosional shores
Well-developed cliffs, Exist where tectonic uplift of coast occurs, U.S. Pacific coast is one example
Isothermal
a change of a system, in which the temperature remains constant
Isohaline
a line or surface drawn on a map or chart to indicate connecting points of equal salinity in the ocean
Thermocline
a steep temperature gradient in a body of water such as a lake, marked by a layer above and below which the water is at different temperatures
Backshore
above high tide line; covered with water only during storms
Barrier islands
are long offshore sand deposits that parallel the coast, Most developed due to rise of sea level about 4,000 years ago, Common East and Gulf coasts of U.S., Protect mainland from high wave activity, can migrate landward over time
Wave-cut cliffs/Sea caves
are other features carved out by wave activity
Recreational beach
area above the shoreline
Offshore
area beyond low tide breaking waves
Salt Marshes
biologically productive wetlands