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24 Cards in this Set
- Front
- Back
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How do volcanoes form? |
Volcanoes form when magma from the mantle rises through weak spot in the earths crust |
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What is the name given when magma cools of inside the earths crust. What type of forces is this part of? |
When magma cools inside the earths crust it is called intrusive volcanism. This is part of intrusive forces |
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How is a stratovolcano formed? |
Stratovolcanoes form by layers of lava from successive eruptions |
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How is an eruption caused? |
An eruption is caused by pressure of dissolved gas building up in the magma |
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What are volcanic bombs? |
Volcanic bombs are large fiery rocks thrown out during an eruption. |
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What are pyroclastic flows? |
Pyroclastic flows is an extremely hot mass of rock and ash |
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Define 'eruption cloud' |
An eruption cloud is ash and toxic gases (includes sulphur dioxide) that pollute the atmosphere |
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Define the term 'lava' and 'lahar' |
Lava: is molten rock that flows slowly but is very destructive Lahar: is swift and silent mud flows that engulf buildings |
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What are caldera volcanoes? |
Caldera volcanoes are domes of stratovolcanoes that have collapsed. This causes a broad circular vent |
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What are shield volcanoes? |
Shield volcanoes form when eruptions of runny basalt does not build in a cone shape |
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Where are most active volcanoes found? |
Active volcanoes are found along the plate boundaries |
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What are batholiths, sill dyke, laccolith and lopolith? |
These are all types of igneous rocks on the surface |
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What does the steepness and structure of a volcano depend on? |
It depends on the intensity of the pressure in the magma chamber, the type of eruption and composition of the lava |
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What are three states of volcanoes? |
Volcanoes can be active, dormant or extinct |
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What are the 4 types of volcanoes? |
Volcanoes can be classified as: 1. cinder cone 2. shield volcanoes 3. lava domes 4. composite volcanoes (stratovolcanoes) |
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What are cinder volcanoes? |
Cinder volcanoes consist of cinders (hardened lava) ejected from a single vent. Usually erupts voilently |
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What are shield volcanoes? |
Shield volcanoes form when lava is very fluid and flows from a number of vents. The cooled lava forms volcanic rock, creating a lava plateau. USUALLY LARGEST VOLCANOES |
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True or False: Lava domes form a small mass of lava that does not flow from the vent |
TRUE |
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What do stratovolcanoes consist of? |
They consist of different layers of ash, cinders and lava. The ejected lava forms a cone shaped mountain. |
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What are conelets? |
Conelets are smaller craters created in the fissure of the slopes on the volcano. They form when magma can no longer reach the main crater |
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What is a caldera? |
A caldera is solidified lava in a crater. A sudden eruption would then blow off the top of the volcanoes (occurs when the volcano has not erupted for a long time). |
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True or False: A caldera can form a lake and a new cone can form in it |
TRUE |
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What are 4 negative effects of volcanoes? |
-Lava flows burn & bury vegetation and buildings -Ash covers building and result in illnesses -Volcanic bombs kill people -Mud slides can occur |
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What are three positive effects of volcanoes? |
1. Fertaliser: Ash can help soil become fertalised 2. Tourist attraction - builds economy 3. Heating systems and electricity generation can be used from hot underground water |
