Coasts
What are Coasts?
The area where the sea and land meet is called a coast. The coasts of the world measure about 193,000 miles approximately. Coastal areas are also known as shores and seasides. They form unique habitats where a range of animals and plants survive in a challenging environment. Glaciers, rivers, and streams deliver a steady supply of building material for nature's unending job.
How Are Coasts Formed?
Coastal land forms are produced by two major processes — erosion and deposition. Erosion is the wearing away of the Earth’s surface by wind or water. Wind and waves create the energy that dissolves the rocks along coastlines. Waves are constantly striking against a coastline. If the wind is heavy and strong, the more powerful are the waves.
As the waves hit the coastline, the energy in them is used to dissolve rocks and move sand, pebbles and other material. Waves carry the sand and other material on and off the shore. When a wave breaks, the water from it runs up the beach. This is called the swash. The movement of water back down the beach to the sea is called the backwash. When storms occur and waves are large, more material is carried in the backwash to deep water. These are called destructive waves. When the waves are small and contain less energy, sand and other materials are more likely to be carried in the swash and laid down as deposits on the
As the waves hit the coastline, the energy in them is used to dissolve rocks and move sand, pebbles and other material. Waves carry the sand and other material on and off the shore. When a wave breaks, the water from it runs up the beach. This is called the swash. The movement of water back down the beach to the sea is called the backwash. When storms occur and waves are large, more material is carried in the backwash to deep water. These are called destructive waves. When the waves are small and contain less energy, sand and other materials are more likely to be carried in the swash and laid down as deposits on the
Coastal Features Formed By Erosion:
Headlands & Bays-
Soft rocks are eroded more quickly by wave erosion than harder rocks. Headlands and bays form along coasts that have alternating resistant (harder) and less resistant (softer) rock. Where there is resistant rock, the coast is worn away more slowly, leaving a headland that juts out into the sea. Where there is softer rock, wave erosion is more rapid and a bay will form. Wave energy is concentrated around headlands, which are eroded forming landforms such as cliffs, caves, arches, stacks and blowholes
Soft rocks are eroded more quickly by wave erosion than harder rocks. Headlands and bays form along coasts that have alternating resistant (harder) and less resistant (softer) rock. Where there is resistant rock, the coast is worn away more slowly, leaving a headland that juts out into the sea. Where there is softer rock, wave erosion is more rapid and a bay will form. Wave energy is concentrated around headlands, which are eroded forming landforms such as cliffs, caves, arches, stacks and blowholes
Caves, Arches & Stacks-
Caves will be formed where weak rocks are eroded on each side of a headland. Over time, the caves will erode enough to join, forming an arch. Further erosion of the rock supporting the arch will cause it to collapse, leaving a stack. When water rushes into a cave, pressure builds up at the back of the cave. If a section of the roof above the cave is weak, it may collapse, forming a blowhole. Blowholes are blasts of water on the top of a certain cave.
Caves will be formed where weak rocks are eroded on each side of a headland. Over time, the caves will erode enough to join, forming an arch. Further erosion of the rock supporting the arch will cause it to collapse, leaving a stack. When water rushes into a cave, pressure builds up at the back of the cave. If a section of the roof above the cave is weak, it may collapse, forming a blowhole. Blowholes are blasts of water on the top of a certain cave.
Coastal Features Formed By Deposition:
Beaches-
Beaches are formed when material is brought to the shore by waves in the swash. The material can be sand, stones, pebbles or other rough substances. Eroding cliffs can be the source of this material as can rivers transporting sediment. Parts of the beach may always be under water; other sections may always be dry.
Beaches are formed when material is brought to the shore by waves in the swash. The material can be sand, stones, pebbles or other rough substances. Eroding cliffs can be the source of this material as can rivers transporting sediment. Parts of the beach may always be under water; other sections may always be dry.
Spits & Tombolos-
The process of longshore drift moves sand and other material along a beach. If this drift occurs constantly in one direction, sand may build up and form an extension of the coastline. This extension is called a spit. A spit can sometimes join two land areas. This type of spit is called a tombolo. Long shore drift along the north-eastern coast of Australia is responsible for creating great sand islands such as North and South Stradbroke, Moreton and more.
The process of longshore drift moves sand and other material along a beach. If this drift occurs constantly in one direction, sand may build up and form an extension of the coastline. This extension is called a spit. A spit can sometimes join two land areas. This type of spit is called a tombolo. Long shore drift along the north-eastern coast of Australia is responsible for creating great sand islands such as North and South Stradbroke, Moreton and more.