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Coastal processes and coastal erosion summary and conclusion articles
Beach erosion effects
Coastal processes and coastal erosion summary and conclusion articles
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The coast is dynamic, meaning it is constantly changing. It does so as a result of erosion and deposition, forming various types of landforms in the process. The landforms of erosion are headlands, bays, cliffs, rock platforms, caves, arches, stacks and blowholes. The landforms of deposition are beaches, lagoons, bars, barriers, spits and tombolos. LANDFORMS OF EROSION Headlands and Bays Along the coast where there are alternating patterns of hard and soft rock, headlands and bays may form as a result of hydraulic action. The harder more resistant rock erodes away slower, forming a headland that juts out into the ocean. When the softer rock between headlands erodes away and at a faster rate, it creates a curved inlet, or bay. Cliffs and Rock Platforms Now the headland is more exposed to the hydraulic action of the waves than the protected bay. As the waves near the shore, they refract and “mould” to the shape of the coastline, …show more content…
It is generally unaffected by erosion by hydraulic action, since waves strike forward rather than downwards. However the platform can be be continued to be shaped by corrasion, which is the abrasion by particles rolling back and forth with the waves. Caves, Arches, Stacks and Blowholes When erosion can carve out sea caves, arches, stacks and blowholes in a headland. Sea caves form when weak areas of headlands and cliffs are hollowed out. The cave could be worn away to reach the other side of the rock, or two sea caves might meet. In both cases, a sea arch results. The waves continue to corrode the rock until the arch collapses due to the weakening of the top portion. All that remains is a stack, which is eventually reduced to a stump by wave erosion. If there is a weak section of rock in the roof of a sea cave, it can collapse from the pressure of compressed air and water when waves rush into the cave. A blowhole is produced. LANDFORMS OF
coast (as shown in pictures 1 & 2). The area of sea is subject to the
Barrier Beaches stretch along the entire east coast of the United States. The barrier beaches from Long Island to Maine are known as Glaciated Coasts because their formation was assisted by glaciers. Eighteen thousands years ago a glacier covered most of the eastern US. This glacier terminated at present day Long Island. About fifteen thousands years ago the glacier began to retreat. As it melted it left behind mounds of rubble, called moraines. This particular glacier left behind two moraines because its final recession was a two part process. These two moraines are the Ronkonkoma Moraine and the Harbor Hill Moraine. The Ronkonkoma Moraine is located in central Long Island and the Harbor Hill Moraine is located on the northern part of Long Island. Besides the two moraines the glaciers deposited great amounts of debris offshore. This debris supplies the sand needed to create and maintain a barrier beach system (Hoel 16-18).
There are many different types of coasts; beaches are just one type. Coasts are divided into two categories: primary coasts, which were created by non-marine processes, and secondary coasts, which were formed by marine action. Primary coasts happen because of changes in the land, such as river deltas or lava flows. Primary coasts are created by erosion, deposition, or tectonic activity. Many of these coastlines were formed as the sea level rose during the last 18,000 years, submerging river and glacial valleys to form bays and fjords. River deltas are an example of a primary coast. They form where a river deposits soil and other material as it enters the sea.
“Concretions, which are compact masses of mineral that form within a pre-existing rock. These nodules are often spherical, elongate, and are harder than the rocks that contain them. They develop around an irregularity within the rock that serves as a nucleus, often a piece of shell, a pebble, or just a harder spot in the rock. As water runs through the rock, it deposits minerals at these irregular spots. Most of the concretions are in the Cliff House Sandstone” (Service, National Park). “Other features are on many of the cliff faces, called desert varnish. Desert varnish forms when manganese, a mineral found either within the rock or in windblown dust, is fixed to the cliff face by bacteria. The bacterial action occurs on the portions of rock wet from runoff water, causing a streaking effect” (Service, National Park). Another distinctive feature called turtle back weathering, develops in the Cliff House Sandstone that is exposed and unprotected on mesa tops. Originally, there was about 1500 feet of rock atop the Cliff House Sandstone. As this overlying rock eroded away, it released a tremendous amount of pressure on the sandstone. The pressure release caused cracks to form in the rocks. Water then weathered these cracks through freezing and thawing or by dissolving some of the
A second project is constructed along Stable Road, the objectives is trying to slow rather than arrest erosion, it adding 10,000 cubic yards to stop the erosion. The restoration is complex with the occurrence of old seawalls, piles of rocks and other structures. Sand-filled Gesture groins are used to locate that is originally to remain in place for up to 2 years. The pipeline is fasten by concrete blocks that attached by fibers straps. In areas the straps broke, it allowing the pipe to move across the reef.
(I): Rock masses yielding low water (WPT) and cement takes (CT) are practically tight and need no treatment:
When a plate collides with another plate, pressure builds up until the rocks suddenly crack and shift.
Mid-ocean ridges (often containing fissures or cracks in the rock) exist near the Earth's crust.
More than 170 million years ago all of the continents formed a single landmass, called Pangaea. Around this time a period of rifting commenced, breaking up Pangaea, forming super-continents and opening vast new oceans. This was the beginning of continental drifting. Continental drifting is an interesting natural occurrence and such immense shifting can lead to earthquakes, which in turn can lead to tsunamis (McCarthy and Rubidge, 2005).
In my first hypothesis, I believe that sinkholes will occur in soil and rock that is soft and wet because sinkholes are known to be associated with limestone bedrock and limestone is easily dissolved by acidic groundwater. Thus, my hypothesis is that when soils and rocks that attract more water, it is easily for a sinkhole to develop because the soil will erode into open cracks or caverns in the ground. This in turn would lead to a surface collapse because the er...
Aeration appears to play an important role within the impact process when the wave loading is applied on the structure. Aeration is defined as the process by which air is circulated through, mixed with or dissolved in a liquid or substance. In this case, aeration refers to the mixture of sea water with air bubbles. The existence of the air content within the water has an effect on the temporal variations of pressure caused by waves breaking on structures (Biackmore & Hewson, 1984; Griffiths, 1994).
As the name suggests (i.e. lateral) this type of erosion occurs at the sides or banks of the river thereby widening the river. This mostly occurs at the banks of the middle and lower courses.
...ver often develops meanders, or a looplike bend in the course of a river, where it flows through easily eroded rock or sediment. Sometimes, meandering rivers form a feature called an oxbow lake, a meander that has been cut off from the river. Deposition creates landforms such as alluvial fans and deltas. An alluvial fan is a wide, sloping deposit of sediment formed where a stream leaves a mountain range. Sediment deposited where a river flows into an ocean or lake builds up a landform called a delta. Groundwater is the term geologist’s use for the underground water. A deposit that hangs like an icicle from the roof of a cave is called a stalactite. Slow dripping builds up a cone shaped stalagmite from the ice floor. Karst topography is a type of landscape in rainy regions where there is limestone near the surface, characterized by caverns, sinkholes, and valleys.
... Now there is an added force from the water called pore pressure and the normal force is decreased making the slope more likely to fail. The following diagram represents this scenario with 'W' as the gravitational force downward of the upper rock, 'p' as the pore pressure from the water, and 'A' as the area that the water affects.
Erosion increases as the length and/or steepness of the slope increases by affecting the volume and velocity of water flow.