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Coastal landforms, Coastal landforms - Coggle Diagram
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Coastal landforms
Headlands and bays
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The coastal erosion processes erode away the weaker rocks more readily that the harder rocks to forma sequence of alternating headlands and bays.
Erosion at the headlands creates landforms such as cliffs and wave-cut platforms. Deposition occurs in the sheltered water of the bay, forming a beach.
Headlands and bays are characteristic features of a discordant coastline where rocks of different hardness (resistance to erosion) are exposed at the coast. Headlands form resistance promontories jutting out into the sea. They are apparated by bays of less-resistant rock where the land has eroded back by the sea.
Beaches
A beach is a dispositional landform made of sand or pebbles (shingle) extending from the low water line to the upper limit of storm waves. Beaches may exhibit a range of small landforms such as abridges called berms (formed by waves just above other high tide line, for example), ripples or shallow water -filled depression called runnels.
Sandy beaches: commonly formed in sheltered bays, associated with relatively low-energy constructive waves. Flat and extensive beaches are often back by sandy dunes.
Pebble beaches: commonly associated with higher-energy coastlines where destructive waves remove finer sand, leaving behind coarser pebbles. Beaches tend to be steep and narrow with distinctive high tides berms.
Caves, arches and stacks
Cave, arches and stacks are commonly formed at headlands where relatively tough rock juts out into the sea. they are formed in seral steps:
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4) Eventually the roof collapses to from an isolated pillar of rock called a stack. Over time the stack will be eroded and will collapses to form a stump, which is only exposed at low tide.
3) Over time, processed of erosion widen the arch and processes of weathering weaken its roof.
1) Cracks in the cliff (joints or faults) are eroded and enlarged by hydraulic action to form a wave-cut notch at the base of the cliff. This is eroded further by hydraulic action and abrasion to from a cave.
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Spits
A spit is a sand or shingle (pebble) ridged most commonly formed by longshore drift operating along a stretch of coastline. It is rather like a narrow beach extending out from the coast into the sea. At its end, where it is more exposed to variations in wind and waves, it tends to curve to form a hook or recurved tip. Some spits have sand dunes on them.
