Coasts

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What are hard rock coasts and what are they made up of?
Consist of resistant rocks (e.g. igneous granite) and resistant sedimentary rocks (e.g. sandstone and limestone)
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What are soft rock coasts and what are they made up of?
Consists of less resistant rocks (e.g. clays and shales), which are more easily eroded
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What is a discordant coast?
A coast with strata at right-angles to the coast. These have different rock types
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What are concordant coasts?
Coasts with strata which is parallel to the coastline. These have the same types of rock along the coast.
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What are igneous rocks?
These are the Earth's oldest rocks, formed from lavas and deep magma. They were molten, cooled and crystallised. Most of these are resistant
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What are sedimentary rocks?
These are formed from sediments eroded and deposited by rivers or the sea. Some are resistant (e.g. limestone). but some are easily crumbled (e.g. shale)
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What are metamorphic rocks?
Sedimentary rocks which were heated and compressed during tectonic activity. This process makes them harder and more resistant (e.g. slate becomes shale)
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What does wave size depend on?
The wind strength, how long the wind blows for and the fetch (i.e. the length of water the wind blows over)
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What are prevailing winds?
The winds which blow most often
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What do summer constructive waves do?
They have a strong swash and transpot sand up the beach. The gentle slope means that the backwash is slow, so sand is deposited. Deposited sands form a bank/berm
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What do winter destructive waves do?
Stronger winds are common so waves have a larger amplitude, a shorter wavelength and arrive much more quickly. They also have a strong backwash eroding sand away and usually form a rip current. Sand is carried away forming a bar
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How does a rip current form?
When the backwash flows under the next incoming wave
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What is hydraulic action?
When water is forced into cracks in rocks, which compresses the air. When the wave retreats the compressed air rushes out, which can force the rock apart.
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What is abrasion?
Sediment is thrown against the cliff by waves, which wears away the cliff and chips bits of rock off of the cliff
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What is attrition?
Loose sediment (from hydraulic action and abrasion) is swirled around by waves. These bits are constantly colliding with other sediment, and gradually gets worn down into smaller, and rounder sediment
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How does coastal erosion happen most commonly?
Abrasion forms a wave-cut notch, which grows creating a cliff overhang. This overhang can become unstable and eventually collapses forming a pile of rock debris. The debris protects from further erosion. Debris erodes away and erosion occurs again
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What happens to sediment over time?
Attrition makes it smaller and rounder or sediment is transported from where it was eroded to new locations
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What is longshore drift?
The movement of material along a coast when the waves are moving at an angle to the coast
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How are sand dunes formed?
Strong onshore winds blow sand inland and build up sand dunes parallel to the shoreline
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How is a spit formed?
Longshore drift carries sand along the shore until it reaches a river estuary where it gets pushed out into the river channel. The river flow halts the drift, so sand is deposited, forming a spit
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When does a spit stop growing?
When deposition of sand, by longshore drift, is balanced by erosion from the river
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Other cards in this set

Card 2

Front

What are soft rock coasts and what are they made up of?

Back

Consists of less resistant rocks (e.g. clays and shales), which are more easily eroded

Card 3

Front

What is a discordant coast?

Back

Preview of the front of card 3

Card 4

Front

What are concordant coasts?

Back

Preview of the front of card 4

Card 5

Front

What are igneous rocks?

Back

Preview of the front of card 5
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