A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean , a lake , or another bay. A large bay is usually called a gulf , sea , sound , or bight . A cove is a small, circular bay with a narrow entrance. A fjord is an elongated bay formed by glacial action. The term embayment is also used for related features , such as extinct bays or freshwater environments.
24-703: Alum Bay is a bay near the westernmost point of the Isle of Wight , England, within close sight of the Needles rock formation. Of geological interest and a tourist attraction, the bay is noted for its multi-coloured sand cliffs. The waters and adjoining seabed form part of the Needles Marine Conservation Zone and the shore and heath above are part of the Headon Warren and West High Down Site of Special Scientific Interest . Alum Bay
48-453: A bay unless its area is as large as (or larger than) that of the semi-circle whose diameter is a line drawn across the mouth of that indentation — otherwise it would be referred to as a bight . There are various ways in which bays can form. The largest bays have developed through plate tectonics . As the super-continent Pangaea broke up along curved and indented fault lines, the continents moved apart and left large bays; these include
72-449: A cafe. During the summer season a chair lift takes tourists to and from the pebble beach below. Alternatively, a footpath leads to the beach via Alum Bay Chine. From the beach boat trips frequently leave to tour the Needles. A traditional product of Alum Bay, and a fixture of Isle of Wight tourist shops, was the creation of ornaments using the coloured sands layered in vials and jars. The sands were also used for sand painting pictures,
96-484: A popular craft in Victorian times known as marmotinto . In the past, visitors to the bay could climb the foot of the cliffs and dig out the sand themselves. The removal of minerals from the site is now prohibited by law under provisions laid out in notices attached to the Headon Warren and West High Down SSSI designation. The Needles Park has a facility where people could make bottles of sand, using sand gathered from
120-417: A typical source of energy to build beaches. Beaches located inside harbours and lagoons are also considered BEBs. BEBs can be unvegetated or partially unvegetated and can be made of sand, gravel or shells. As a consequence of the sheltering, the importance of other sources of wave energy, including locally generated wind waves and infragravity waves , may be more important for BEBs than for those beaches on
144-415: Is a primary control for the shape, volume and stability of BEBs, and the location and orientation of the beach inside the estuary or bay are important controls on its morphodynamic equilibrium. The hydrodynamic processes (i.e., waves and currents) that control the shape and equilibrium of BEBs are largely determined by the geometric configuration of the estuary/bay; this includes the width and orientation of
168-454: Is the location of a classic sequence of upper Paleocene and Eocene beds of soft sands and clays, separated by an unconformity from the underlying Cretaceous Chalk Formation that forms the adjoining headland of West High Down. Due to geological folding of the Alpine orogeny , the strata in the main section of the bay are near vertical, with younger rocks with progressively lower dips to
192-579: The Bay of Bengal and Hudson Bay, have varied marine geology . The land surrounding a bay often reduces the strength of winds and blocks waves . Bays may have as wide a variety of shoreline characteristics as other shorelines. In some cases, bays have beaches , which "are usually characterized by a steep upper foreshore with a broad, flat fronting terrace". Bays were significant in the history of human settlement because they provided easy access to marine resources like fisheries . Later they were important in
216-680: The Gulf of Guinea , the Gulf of Mexico , and the Bay of Bengal , which is the world's largest bay. Bays also form through coastal erosion by rivers and glaciers . A bay formed by a glacier is a fjord . Rias are created by rivers and are characterised by more gradual slopes. Deposits of softer rocks erode more rapidly, forming bays, while harder rocks erode less quickly, leaving headlands . Beaches in estuaries and bays Beaches in estuaries and bays (BEBs) refer to beaches that exist inside estuaries or bays and therefore are partially or fully sheltered from ocean wind waves , which are
240-611: The Haven Hotel , Poole 20 miles away. 50°39′59″N 1°34′34″W / 50.66639°N 1.57611°W / 50.66639; -1.57611 Bay A bay can be the estuary of a river, such as the Chesapeake Bay , an estuary of the Susquehanna River . Bays may also be nested within each other; for example, James Bay is an arm of Hudson Bay in northeastern Canada . Some large bays, such as
264-600: The Ichthyofauna of low energy BEBs in Southern Brazil showed their dependance on salinity and energy. BEBs are often small and isolated and not as iconic as open-ocean beaches in popular culture; and may have a history of litter, pollution and dereliction. However, BEBs are often located around major cities and provide an important recreational and cultural resource. BEBs provide calm swimming opportunities for young children. They can be immensely popular, like
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#1732779780971288-481: The adjacent BEBs, however, living reefs can create undesired coastal changes related to interrupting sediment transport pathways and excessive wave attenuation. BEBs, like all beaches, are accumulations of unconsolidated sediment (i.e., sand) within the cross-shore limits of wave action and occur where there is a suitable supply of sediment and exposure to waves that are energetic enough to move sediment and overcome stabilization by vegetation. The underlying geology
312-798: The beaches in the Pará River (Amazon Coast of Brazil) or in Sydney Harbour , or little-known, as are some in San Francisco Bay. BEBs provide protective buffers for wetlands and coastal development and it is important to protect them. The seagrass that often fronts these systems in Australia is endangered and ecological restoration projects such as Operation Posidonia are in place to restore this seagrass. Other coastal protections placed in estuaries, like oyster reefs, are believed to attenuate erosive waves and therefore protect
336-527: The development of sea trade as the safe anchorage they provide encouraged their selection as ports . The United Nations Convention on the Law of the Sea defines a bay as a well-marked indentation in the coastline, whose penetration is in such proportion to the width of its mouth as to contain land-locked waters and constitute more than a mere curvature of the coast. An indentation, however, shall not be regarded as
360-429: The entrance and the width, length and depth of the estuary/bay. For example, tidal currents are strong at constrictions like at the mouth of bar-built estuaries; estuaries or bays with wide mouths allow propagation of ocean waves; and, the existence of a large enough wind fetch within an estuary or bay allows the development of locally-generated wind waves. However, BEBs primarily exist in fetch-limited conditions, causing
384-777: The equatorial zone like, for example, the Amazon estuarine beaches. BEBs are found all around the world, including in large cities such as San Francisco , Sydney , Lisbon , London and Shanghai for example. While sometimes relatively small by area, they can provide a large range of resources. In addition to their ecological importance, BEBs can provide spaces in urban-settings for people to connect with nature, and protection for landward areas and infrastructure. BEBs provide critical habitats and feeding areas for local fish and birds. Even small patches of sand can provide critical habitat. Many BEBs are fronted by sea grass and may allow marshes to develop behind them. BEBs in estuaries are
408-683: The estuary/bay and the geometric configuration of the estuary/bay. The morphology and characteristics of BEBs vary broadly depending on geology, sediment availability and hydrodynamic energy. They can be narrow and low and exist under low-energy conditions or they can be directly exposed to swell waves propagating into the estuary, in which case they might resemble a beach on the open coast, but still be controlled by different processes. They can occur in all tidal conditions, from micro- to macro-tides, and under strong river flows to no river flow. BEBs may be low energy, sheltered, fetch-limited, lagoonal, backbarrier, and elsewhere, therefore, they have been noted in
432-530: The frequent rockfalls. In the past it was possible to buy Alum Bay coloured sand by mail order and make one's own sand pictures and bottles at home. Southern Vectis run bus services from Alum Bay, including two summer-only open top services – the Needles Breezer and the Island Coaster. On a map of the area produced around 1590, the bay is named Whytfylde Chine. It is possible that Alum Bay
456-583: The geologic and biologic factors on beach shape to have outsize importance. Typical gradients from the entrance to the inner estuary or bay are observed: Other social factors like population and nearby infrastructure control the degree to which a beach is affected by boat wakes and engineering works that can change the geometry of the bay. In fact, most bays and estuaries hosting large cities are strongly modified, for example, San Francisco , Shanghai , Sydney, or London . BEBs can be controlled by different types of wave energy depending on their location inside
480-472: The habitat for Horseshoe crabs , which during spawning, if combined with moderate wave heights, modify the beach profile such as it becomes concave, similar to a storm profile and lowering the wave-energy threshold for morphological response. Studies in Jamaica Bay showed that the ecological restoration of Horseshoe crabs was limited by the extent of the beach instead of the water quality. Studies of
504-400: The literature with very different names. Here are a few examples: When BEBs are exposed to waves larger than the dominant conditions, they undergo erosion. The volume of erosion can be smaller than the volumes eroded from open-coast beaches, but they might represent a large percentage of the total volume of the beach. The destination of the sand eroded from the beach is not clear, in some cases
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#1732779780971528-406: The open coast. Boat wakes, currents driven by tides , and river inflow can also be important for BEBs. When BEBs receive insufficient wave energy, they can become inactive, and stabilised by vegetation; this may occur through both natural processes and human action. BEBs exist in all latitudes from beaches located in fjords and drowned river valleys ( rias ) in high latitudes to beaches located in
552-483: The west. The sands are coloured due to oxidised iron compounds formed under different conditions. Alum Bay Chine begins as a small wooded valley descending eastward from the junction of the B3322 and the road to Headon Hall. It soon broadens into the clay ravine through which the path and chairlift from Needles Park descend to the beach. On the clifftop there is an amusement park with fairground rides, souvenir shops and
576-610: Was once fed by a Chine by this name, which has long since eroded away. Alum Bay sand includes extremely pure white silica, which was once extracted for glass and pottery manufacture. Guglielmo Marconi moved to Alum Bay in 1897 to experiment with radio. He installed a 40-metre radio antenna outside the Needles Hotel in Alum Bay. Initially establishing communication with ships offshore, by early 1898 he had successfully communicated with stations at Madeira House, Bournemouth and
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