There are many landforms associated with a bay.
A bay is an indentation along the shoreline of a lake or ocean.Bays may be drowned river valleys between mountains or hills that were originally carved by glacial ice. Or they may be water-filled, fault-controlled valleys that lay along a path of tectonic weakness where dissimilar types of rock converge. Wind, water, slope, tides and fault lines all have a part in the formation of bays and their associated landforms.
The Bay Floor and Beach
Landforms associated with the bay floor are the bay bottom and the mainland cove. The bay bottom is the central part of the bay floor and is level and firm, with a gravelly surface. Mainland coves are areas adjacent to the shore that form a smaller embayment within the larger bay. The soil surface is sandy or loamy. Wave energy is directed toward headlands, so less wave energy is directed toward a bay. A bayhead beach, therefore, is a low energy accumulation of gently sloped sand or gravel adjacent to the back of a bay.
Types of Wetlands
A river that empties into a bay may form an estuary at its mouth. An estuary is a transitional area between the fresh water of the river and salt water in the bay. An estuary is often bordered by a wetland marsh, land that is constantly or sporadically waterlogged. Marshes and estuaries are affected by ocean tides and are sediment sinks, accumulating sediment from the land. Deltas are large bodies of sediment deposited at the mouth of a river. The Mississippi Delta is so extensive that it forms bays of its own. A lagoon is a body of salt water separated from the larger embayment by a sandspit.
Barriers
Currents, wind and wave action help form sandspits.
A sandspit is a linear accumulation of sediment deposited parallel to the shore and sculpted by wind and waves. When two spits join, a cuspate foreland is formed. An offshore island or rock may refract incoming waves so a spit of sand advances from the shore toward the island; this is a tombolo. If a sandspit grows so it completely blocks the mouth of a bay, it is known as a bay barrier. A bayhead barrier is found in the upper reaches of a bay and divides the main bay from an area of lagoon or marshland. A baymouth barrier, or bar, forms between headlands with a lot of wave action; it is often submerged at high tide and exposed at low tide.
Islands, Reefs and Channels
Reefs are underwater landforms that are solid and rock-like in structure. They are formed of marine organisms, lava flows or rock outcroppings. Sea islands are formed by mainland flooding due to gradual sea level rise. Channels are deep, linear, navigable passages between islands, or between the coast and an island. Beach ridge islands form when wind piles sand into dunes that are distinctively ridged, often with wetlands between ridges; they are also known as barrier islands.
Headlands and Cliffs
Differential rates of erosion account for headlands.
Steep shorelines, undercut and collapsed by waves and erosional currents, may become vertical precipices, known as sea cliffs. The material that falls from cliffs as they erode is carried to deeper water and forms a level, submerged surface, called a wave-built terrace. Cliffs sometimes erode unevenly; the portion of the cliff more resistant to erosion juts out further into the water and is called a headland. The faster eroding portions become bays and inlets.
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