Why is the coast eroding? Do You Know That Article From TamilYoungsters.com
Coastal erosion is the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, drainage or high winds (see also beach evolution). Waves, generated by storms, wind, or fast moving motor craft, cause coastal erosion, which may take the form of long-term losses of sediment and rocks, or merely the temporary redistribution of coastal sediments; erosion in one location may result in accretion nearby. The study of erosion and sediment redistribution is called 'coastal morphodynamics'. It may be caused by hydraulic action, abrasion, impact and corrosion.
On non-rocky coasts, coastal erosion results in dramatic (or non-dramatic) rock formations in areas where the coastline contains rock layers or fracture zones with varying resistance to erosion. Softer areas become eroded much faster than harder ones, which typically result in landforms such as tunnels, bridges, columns, and pillars. Also abrasion commonly happens in areas where there are strong winds, loose sand, and soft rocks.The blowing of millions of sharp sand grains creates a sandblasting effects. This effect helps to erode, smooth and polish rocks.The definition of abrasion is grinding and wearing away of rock surfaces through the mechanical action of other rock or sand particles.
Why is the coast eroding?
Water is not given enough credit for the role it plays in shaping Earth. Tectonic plates and volcanic eruptions are often cited as the culprits for most land features, but it is water and wave action that shapes our world’s coastlines. When a wave crashes on the shore it carries sediments that are suspended in the water, and it pushes larger sediments along the ground too. When a wave recedes it also takes sediment with it, but rarely at an equal rate. If a wave deposits more sediment than it takes away then this sediment builds up, causing coastlines to extend. Conversely, when more sediment is being removed than added, the coastline recedes or erodes. Coastal erosion is responsible for some of the most amazing landforms we know today, from the Twelve Apostles in Australia to the White Cliffs of Dover in England. The type of coastline that is created from erosion varies greatly depending on any number of factors, including the strength of the wave action and wind, the sediment composition of the coastline and the types of nearby rock. Coastal erosion is a very slow process, taking hundreds of years, but scientists believe that climate change is speeding things up. Climate change has caused a rise in sea levels and storm frequency and severity – both of which play a key role in erosion. Indeed, the UK’s Environment Agency estimates that the British coastline could erode from 67-175 metres (220-575 feet) over the next 100 years.
Sea stack formation
1. Cracks
--Water finds the weakest point in the rock of a headland and then creates small cracks through hydraulic action.
--Cave
As the waves break against the cracks, they open out into a small cave, which becomes larger and larger as time goes by.
2.Arch
Wave action from both sides of the cave causes it to break open, forming an arch-shaped structure over the sea.
3. Stack
Eventually, the meeting point of the tip of the arch and the headland will collapse, leaving a free-standing stack, separated entirely from the headland.
4. Stump
The stack gets eroded away even further until it eventually leaves just a stump, which is often covered at high tide.
5.Rock type
Medium-density rocks like sedimentary or volcanic rocks usually form sea stacks; softer rocks like clay erode too quickly.
6.Headland
Harder-density rocks remain jutting out into the ocean where the coastline has receded behind it, usually creating bays.
7.Top of stack
Sea stacks are a popular nesting site for seabirds as they are isolated and difficult for predators to reach.
Longshore drift currents explained
1.Swash
2.Sediment
3.Backwash
1.Longshore current
1.Sand spit
