Shield Volcanoes
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- Barring the basalt flows, the shield volcanoes are the largest of all the volcanoes on the earth.
- Example- Hawaiian volcanoes
- These volcanoes are mostly made up of basalt, a type of lava that is very fluid when erupted.
- For this reason, these volcanoes are not steep.
- They become explosive if somehow water gets into the vent; otherwise, they are characterised by low-explosivity.
- The upcoming lava moves in the form of a fountain and throws out the cone at the top of the vent and develops into cinder cone.
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Composite Volcanoes
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- These volcanoes are characterised by eruptions of cooler and more viscous lavas than basalt.
- These volcanoes often result in explosive eruptions.
- Along with lava, large quantities of pyroclastic material and ashes find their way to the ground.
- This material accumulates in the vicinity of the vent openings leading to formation of layers, and this makes the mounts appear as composite volcanoes more than 50 m.
- Individual flows may extend for hundreds of km.
- The Deccan Traps from India, presently covering most of the Maharashtra plateau, are a much larger flood basalt province.
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Mid-Ocean Ridge Volcanoes
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- These volcanoes occur in the oceanic areas.
- There is a system of mid-ocean ridges more than 70,000 km long that stretches through all the ocean basins.
- The central portion of this ridge experiences frequent eruptions.
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