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The Work of the Sea (Features of Sea Erosion (Sea Caves, Arches and Stacks…
The Work of the Sea
Features of Sea Erosion
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Sea Caves, Arches and Stacks
Sea Caves
A sea cave is a large hole or tunnel at the foot of a cliff. Waves find a weak spot at the base of a cliff and gradually erode it until a cave is formed.
Sea Arch
A sea arch is a natural archway in a rocky headland. If a cave erodes right through a headland (or if two caves erode through from either side), an arch may form.
Sea Stack
A sea stack is a pillar of rock sticking out of the sea near the coast. If the roof of an arch collapses, its outer wall may stand out as a pillar of rock.
Bays and Headlands
A bay is a large, curved opening into the coast.
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Blow Holes
A blow hole is a hole which joins the roof of a cave with the surface above. It is a blow hole because sea spray may be blown up through it in stormy weather.
Transport by the Sea
The mud, sand and shingle (pebbles and stones) carried along by the sea are called its load.
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Sea Deposition
Spits
- A spit is a narrow ridge of sand or shingle. One end juts out into the sea, while the other is connected to the land.
- Longshore drift stops when it reaches a bay or other sheltered place. The material carried by the longshore drift is deposited at these places and may build up gradually to form a spit.
Beaches
- A beach is a gently sloping area of sand or shingle that occurs between high and low tide levels.
- When waves break they lose their power and begin to deposit the material they are carrying.
- The swash pushes materials up the beach. Some of the swash seeps into the beach. The weaker backwash can then pull only finer material back down. That is why large stones are often found at the top of a beach, with finer gravel and sand on the lower beach.
Bars
- A bar is a narrow ridge of sand or shingle which seals off the mouth a bay.
- A spit may grow in length until it completely seals off a bay. The former spit is then referred to as a bar. A lagoon is a small lake formed behind the bar. It was originally part of the bay, which was sealed off by the bar.
Tombolos
- A tombolo is narrow ridge of sand or shingle, which joins an offshore island to the mainland.
- A spit may grow in length until its seaward end reaches a nearby island. The former spit is then referred to as a tombolo.
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