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29-576: The Matagorda Peninsula ( / ˈ m æ t ə ˈ ɡ ɔːr d ə / ) is a narrow spit of land on the southeastern coast of Texas in the United States . The peninsula is in Matagorda County , Texas. The barrier island lies between Matagorda Bay , an estuary , and the Gulf of Mexico . The Texas Gulf Coast island has a water exchange of two to five tidal inlets suspending

58-445: A beach , the term shoal can be applied to larger geological units that form off a coastline as part of the process of coastal erosion, such as spits and baymouth bars that form across the front of embayments and rias . A tombolo is a bar that forms an isthmus between an island or offshore rock and a mainland shore. In places of reentrance along a coastline (such as inlets , coves , rias, and bays), sediments carried by

87-433: A longshore current will fall out where the current dissipates, forming a spit. An area of water isolated behind a large bar is called a lagoon. Over time, lagoons may silt up, becoming salt marshes . In some cases, shoals may be precursors to beach expansion and dunes formation, providing a source of windblown sediment to augment such beach or dunes landforms. Since prehistoric times, humans have chosen some shoals as

116-400: A shoal complex . The term shoal is also used in a number of ways that can be either similar to, or quite different from, how it is used in geologic, geomorphic, and oceanographic literature. Sometimes, the term refers to either any relatively shallow place in a stream , lake , sea , or other body of water; a rocky area on the seafloor within an area mapped for navigation purposes; or,

145-480: A beach, they slow down, their wave height increases and the distance between waves decreases. This behavior is called shoaling , and the waves are said to shoal. The waves may or may not build to the point where they break , depending on how large they were to begin with, and how steep the slope of the beach is. In particular, waves shoal as they pass over submerged sandbanks or reefs. This can be treacherous for boats and ships. Shoaling can also refract waves, so

174-410: A growth of vegetation on the bottom of a deep lake, that occurs at any depth, or is used as a verb for the process of proceeding from a greater to a lesser depth of water. Shoals are characteristically long and narrow (linear) ridges. They can develop where a stream , river , or ocean current promotes deposition of sediment and granular material , resulting in localized shallowing (shoaling) of

203-481: A hook or recurved spit. Refraction in multiple directions may create a complex spit. Waves that arrive in a direction other than obliquely along the spit will halt the growth of the spit, shorten it, or eventually destroy it entirely. The sediments that make up spits come from a variety of sources including rivers and eroding bluffs, and changes there can have a major effect on spits and other coastal landforms. Activities such as logging and farming upstream can increase

232-412: A river) becomes too great to allow the sand to deposit. Vegetation may then start to grow on the spit, and the spit may become stable and often fertile. A spit may be considered a special form of a shoal . As spits grow, the water behind them is sheltered from wind and waves, and a salt marsh is likely to develop. Wave refraction can occur at the end of a spit, carrying sediment around the end to form

261-421: A smaller body of water from the sea, such as: The term bar can apply to landform features spanning a considerable range in size, from a length of a few meters in a small stream to marine depositions stretching for hundreds of kilometers along a coastline, often called barrier islands . They are typically composed of sand , although they could be of any granular matter that the moving water has access to and

290-420: Is a deposition bar or beach landform off coasts or lake shores. It develops in places where re-entrance occurs, such as at a cove's headlands , by the process of longshore drift by longshore currents. The drift occurs due to waves meeting the beach at an oblique angle, moving sediment down the beach in a zigzag pattern. This is complemented by longshore currents, which further transport sediment through

319-439: Is a navigation or grounding hazard, with a depth of water of 6 fathoms (11 meters) or less. It therefore applies to a silt accumulation that shallows the entrance to or course of a river, or creek. A bar can form a dangerous obstacle to shipping, preventing access to the river or harbor in poor weather conditions or at some states of the tide . In addition to longshore bars discussed above that are relatively small features of

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348-436: Is a sedimentary deposit formed at a harbor entrance or river mouth by the deposition of freshwater sediment or by the action of waves on the sea floor or on up-current beaches. Where beaches are suitably mobile, or the river's suspended or bed loads are large enough, deposition can build up a sandbar that completely blocks a river mouth and dams the river. It can be a seasonally natural process of aquatic ecology , causing

377-780: Is called the proximal end, and the end jutting out into water is called the distal end. There is debate as to the longest spit in the world, with both the Arabat Spit in the Sea of Azov and the Younghusband Peninsula in South Australia approximately 110 kilometres (68 mi) long. Alternatively, with the natural closing of the Roanoke inlet in 1811, Bodie Island in North Carolina may qualify as

406-427: Is capable of shifting around (for example, soil , silt , gravel , cobble , shingle , or even boulders ). The grain size of the material comprising a bar is related to the size of the waves or the strength of the currents moving the material, but the availability of material to be worked by waves and currents is also important. Wave shoaling is the process when surface waves move towards shallow water, such as

435-825: The Curonian Lagoon from the Baltic Sea ; it is 98 km long (61 mi). In a similar fashion, the Vistula Spit separates the Vistula Lagoon from the Gdańsk Bay off the coast of Poland . Zlatni Rat , a popular pebble beach jutting southward from the harbor town of Bol , on the Croatian island of Brač , is formed by Adriatic currents flowing east and west through the Hvar Channel , along

464-653: The Morro Bay is one such location. Bar (landform) In oceanography , geomorphology , and geoscience , a shoal is a natural submerged ridge , bank , or bar that consists of, or is covered by, sand or other unconsolidated material, and rises from the bed of a body of water close to the surface or above it, which poses a danger to navigation. Shoals are also known as sandbanks , sandbars , or gravelbars . Two or more shoals that are either separated by shared troughs or interconnected by past or present sedimentary and hydrographic processes are referred to as

493-399: The tides in marginal sea . The Matagorda Ship Channel located on the peninsula produces a substantial tidal range of seawater bearing north-south of the barrier island. This article about a location in Matagorda County, Texas is a stub . You can help Misplaced Pages by expanding it . Spit (landform) A spit ( cognate with the word for a rotisserie bar) or sandspit

522-474: The beach slopes more gradually at one end than the other. Sandbars, also known as a trough bars, form where the waves are breaking, because the breaking waves set up a shoreward current with a compensating counter-current along the bottom. Sometimes this occurs seaward of a trough (marine landform). Sand carried by the offshore moving bottom current is deposited where the current reaches the wave break. Other longshore bars may lie further offshore, representing

551-406: The break point of even larger waves, or the break point at low tide. In Russian tradition of geomorphology , a peresyp is a sandbar that rises above the water level (like a spit ) and separates a liman or a lagoon from the sea. Unlike tombolo bars, a peresyp seldom forms a contiguous strip and usually has one or several channels that connect the liman and the sea. A harbor or river bar

580-417: The direction the waves are breaking, forming an above-water spit. Without the complementary process of littoral drift, the bar would not build above the surface of the waves becoming a spit and would instead be leveled off underwater. Spits occur when longshore drift reaches a section of headland where the turn is greater than 30 degrees. The spit will continue out into the sea until water pressure (e.g. from

609-422: The formation of estuaries and wetlands in the lower course of the river. This situation will persist until the bar is eroded by the sea, or the dammed river develops sufficient head to break through the bar. The formation of harbor bars that prevent access for boats and shipping can be the result of: In a nautical sense, a bar is a shoal, similar to a reef : a shallow formation of (usually) sand that

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638-520: The longest, also measuring in at approximately 70 miles (110 km) to the peninsula's terminus at the Oregon Inlet . The longest spit in a freshwater body of water is Long Point, Ontario , which extends approximately 32 km (20 mi) into Lake Erie . Farewell Spit in New Zealand , at 32 km (20 mi), in the north-west area of South Island , is believed to be caused by

667-437: The sediment load of rivers, which may hurt the intertidal environments around spits by smothering delicate habitats. Roads or bulkheads built along bluffs can drastically reduce the volume of sediment eroded, so that not enough material is being pushed along to maintain the spit. If the supply of sediment is interrupted the sand at the neck (landward end) of the spit may be moved towards the head, eventually creating an island. If

696-479: The southern side of the island. The spit bends slightly west or east, changing its direction gradually, depending on the conditions of the tides and weather. Since prehistory humans have chosen certain spit formations as sites for human habitation. In some cases, these sites have been chosen for proximity to marine resource exploitation ; the Chumash Native American prehistorical settlement on

725-728: The strong prevailing winds and currents, bringing sand eroded from the Southern Alps of the South Island and depositing these into Golden Bay . A well-known spit in the UK is Spurn Point at the Humber ; it is approximately 4.8 km (3.0 mi) long. Another is Chesil Beach in the UK, which connects the Isle of Portland to the mainland. The Curonian Spit , off the coast of Lithuania and Kaliningrad Oblast of Russia , separates

754-412: The supply is not interrupted, and the spit is not breached by the sea (or, if across an estuary, the river), the spit may become a bar , with both ends joined to land, and form a lagoon behind the bar. If an island lies offshore near where the coast changes direction, and the spit continues to grow until it connects the island to the mainland, it is called a tombolo . The end of a spit attached to land

783-462: The water alongside the beach. These currents are caused by the same waves that cause the drift. Where the direction of the shore inland re-enters , or changes direction, for example at a headland , the longshore current spreads out or dissipates. No longer able to carry the full load, much of the sediment is dropped. This is called deposition. This submerged bar of sediment allows longshore drift or littoral drift to continue to transport sediment in

812-404: The water. Marine shoals also develop either by the in-place drowning of barrier islands as the result of episodic sea level rise or by the erosion and submergence of inactive delta lobes . Shoals can appear as a coastal landform in the sea , where they are classified as a type of ocean bank , or as fluvial landforms in rivers, streams, and lakes . A shoal–sandbar may seasonally separate

841-402: The waves change direction. For example, if waves pass over a sloping bank which is shallower at one end than the other, then the shoaling effect will result in the waves slowing more at the shallow end. Thus, the wave fronts will refract, changing direction like light passing through a prism. Refraction also occurs as waves move towards a beach if the waves come in at an angle to the beach, or if

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