Rivers flow sediment into the oceans between plates. Sediment forms layers on the ocean floor. The plates push together causing the sediment to be compressed. Rivers continue to add more sediment. The sediments form rocks that begin to fold upwards.
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Tilt meters
Scientists use these to measure the shape of the volcano and to detect changes
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Sulphur dioxide emissions
Measuring these allows scientists to detect a build up of gas before an eruption
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Seismographs
Using these means that tremors can be detected which could signify an eruption is about to happen
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Yellowstone (Super volcano)
Very wide- 64km
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What is a pyroclastic flow?
500 degree hot, fast-moving ash, rock, gasses and steam flow from a volcano travelling at 130km per hour
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Why are pyroclastic flow dangerous?
So fast- No time to escape or prepare. Poisonous and dangerous. The hot ash is too dense and flows down volcano at high speed, unpredictable.
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How do supervolcanos erupt?
Rising magma cannot escape and large bulge appears on the surface. Cracks appear in the surface and gas and ash erupt from the magma chamber. The magma chamber collapses forming a depression called a caldera
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Distribution of earthquakes
-Happen at all plate boundaries. -Dont happen at the centre of plate boundaries they start on the edges. -Earthquake begins deep within the earths crust at the focus; deep-focus earthquakes are less damaging and are felt less than shallower ones.
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Distribution of earthquakes 2
At the epicenter, above the focus; the earthquake is most strongly felt. Radiating out from the epicentre are seismic waves/shock waves
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Explain why the UK gets really powerful winds-
Waves travel from the caribbean to the UK. This means that the fetch is longer. As a result the wind has time to blow. This means that the waves are taller and closer together
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Longshore drift
Swash, backwash- Goes back out at a 90 degree angle. Longshore drift is how beach material is carried along the beach by waves.
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Groin- Goes out to sea at a right angle
When sediment moves to the next groin, one side of the groin will be higher than the other side which will be lower as beach material has been moved to the next groin
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How a bay is formed
When you have clay, a softer rock sandwiched between two harder rocks such as limestone and chalk, the softer rock erodes faster forming a horse shoe shape called a bay.
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Sandy Beach (Sand)
Sandy beaches are made from constructive waves which deposit fine sediment onto the land. They are flat and smooth and have dunes behind.
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Shingle Beach (Pebbles)
(Sand is at the bottom as large rocks are hurled to the top) Made from powerful contructive waves which hurl larger sediment onto the land. They are steeper and have a ridge/berm.
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Berm
Created when storm waves hurl pebbles and create shingle ridges called a berm.
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Waves
Transport material along longshore drift
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Constructive Waves tend to-
Deposit beach material when they run out of energy when the beach is sheltered eg; by bays
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Tombolo
A ridge of sand and shingle joinung tjhe mainland to an island (Formed- Deposition of sediment continues until the spit joins an island)
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Bars
A ridge of sand and shingle joining two headlands (Form- When a spit forms across a bay and it extends to cover both ends/headlands)
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Lagoon
This is a salt water lake behind a bar. Often fills up with sediment to make a salt marsh. (Forms- When a spit blocks off a bay, salt water is trapped creating a lagoon)
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Other cards in this set
Card 2
Front
Tilt meters
Back
Scientists use these to measure the shape of the volcano and to detect changes
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