The restless earth and rocks

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How many major plates are there?
7.
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What are the two types of plates?
Oceanic, and Continental Plates.
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Oceanic Plates definition?
Oceanic plates, which are made of basalt and are between 5km and 10km thick.
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Continental plates definition?
Continental plates which are made of granite and are between 25km and 90km thick.
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Which are denser, Oceanic or Continental?
Oceanic plates.
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What is a plate margin?
The places where two or more plates meet.
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How is a fold mountain formed?
They are formed on the destructive plate margins, where two plates push together. The rocks in the crust are compressed and folded into anticlines and synclines to form new mountain ranges.
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What is a geosyncline?
A very large download in the Earth's crust, which fills up over time with sediment. Eventually, it may be uplifted to form a new range of fold mountains.
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How are destructive Plate Margins formed?
Oceanic and Continental plates push together. Denser oceanic crust is forced down into the mantle (subduction) forming an oceanic trench. Continental crust is compressed to form fold mountains with composite volcanoes. Major earthquakes occur.
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How are Constructive Plate Margins formed?
Oceanic or continental plates pull apart. Lava erupts forming shield volcanoes. Undersea volcanoes form mid ocean ridges. Minor earthquakes occur when the plates move.
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How are Conservative Plate Margins formed?
Plates are pushed in different directions, or at different speeds. Plates remain locked together until the rock breaks along a fault line. Major earthquakes occur as stored energy is released. There are no volcanoes.
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Which type of plate is thickest?
Continental.
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Which type of plates is made of basalt?
Oceanic
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What is the difference between syncline and anticline?
Syncline- Downfolds. Anticline- Upfolds.
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Where are fold mountains formed?
Destructive plate margins.
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What process forms an oceanic trench?
Destructive plate margins.
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Where are shield volcanoes found?
Constructive plate margins and above hotspots .
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Features of a shield volcano?
Basic Lave (1200C) is runny and flows long distances before cooling and solidifying. Many gentle eruptions form a very large cone-shaped mountain with gently sloping sides, often under the sea.
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Where are Composite volcanoes found?
They are found on Destructive plate margins.
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Features of a Composite volcano?
Acid Lave-(800c) is thick and sticky. Alternate explosive eruptions of ash followed by gentle eruptions of lave build a cone-shaped mountain with steep sides.
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Where are Supervolcanoes found?
Destructive plate margins and above hotspots.
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Features of a supervolacano?
Massive explosive eruptions of ash form a sunken crater, called a caldera. The crater can be over 40 miles wide. Ash would fall across the whole world killing people, wildlife and vegetation. Ash in the atmosphere would trigger global cooling.
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What is a hotspot?
A volcanic "hotspot" is an area in the upper mantle from which heat rises in a plume from deep in the Earth.
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The cause of earthquakes?
Plates are locked together by friction, and pressure builds over many years. Suddenly, the crustal rock breaks underground at a weak point in the rock. Stored energy is released in just seconds and travels outwards from the epicentre as shock waves.
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What records Earthquakes?
seismometer.
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Richer Scale?
Measures energy released (1-10)
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Mercalli Scale?
Measures damage caused (1-12)
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Igneous rocks?
Are formed from molten rock (magma): Granite-intrusive igneous rock, multicoloured with coarse texture. Basalt- Extrusive igneous rock, dark colour with fine texture.
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Sedimentary Rocks?
Are formed in layers from small particles: Chalk- Shells of tiny sea creatures. Limestone- coral and shells of sea creatures. Sandstone- Grains of sand cemented together. Clay- Particles of silt and clay.
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Metamorphic Rocks?
Are formed from sedimentary or igneous rocks under extreme heat and/or pressure: Marble- formed from chalk and limestone. Slate- formed from clay and mudstone. Quartzite- formed from sandstone.
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Weathering?
The breaking down of rocks at the earth's surface by natural processes.
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Chemical weathering?
Chemical weathering occurs from carbonation.
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Chemical Weathering process?
Rainwater absorbs carbon dioxide (co2) from the atmosphere to make acid rain. Acid rain runs into cracks in the rocks' surface. Cracks are weak points and are attacked first. Rocks made of calcium carbonate, such as limestone, are slowly dissolved.
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Mechanical Weathering?
Occurs through Freeze-thaw and exfoliation.
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Freeze-thaw?
Water seeps into cracks in the rock during the day. The water freezes, turns to ice and expands. The crack is enlarged. The ice melts and the process begins again.
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Exfoliation?
The sun heats the rocks during the day, making them expand. At night, the rocks cool and contract. The stress caused buy this expansion and contraction fractures the outside layers.
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Other cards in this set

Card 2

Front

What are the two types of plates?

Back

Oceanic, and Continental Plates.

Card 3

Front

Oceanic Plates definition?

Back

Preview of the front of card 3

Card 4

Front

Continental plates definition?

Back

Preview of the front of card 4

Card 5

Front

Which are denser, Oceanic or Continental?

Back

Preview of the front of card 5
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