Question.
Describe the extrusive landforms produced by volcanic activity. (UPPSC 2017)
Answer.
Volcanoes are one type of endogenic force as well as a natural disaster. A volcano is a place where lava, gases, and ashes escape to the ground.
Major volcanic activities on the earth happen on the margin of tectonic plates, however, some volcanic eruptions are also found in the weak zone of the crust. In the volcanic eruption, hot magma along with the gases and dust particles comes from the Asthenosphere[10 to 100 km depth) and when this magma came up to the surface it is known as lava. Some magma cooled off before reaching the earth's surface within the crust and they form varieties of landforms; these landforms are called intrusive landforms.
When the lava cools off on the earth's surface and forms a variety of landforms; these landforms are called extrusive landforms.
The following are types of extrusive landforms:
- Volcanic Vents
- Volcanic Craters
- Volcanic Crater lake
- Calderas
- Lava plateau
- Volcanic mountains
- Mid-oceanic ridge
- Hot springs
pic: from NCERT
Volcanic vents:
- The volcanic vent is an opening crust where lava comes out from the Asthenosphere.
Volcanic crater:
- A volcanic crater is a funnel-shaped depression that lies around the volcanic vent.
Crater lakes:
- When water gets deposited in the volcanic crater, it forms a beautiful lake which is commonly referred to as a Crater lake.
Calderas:
- When volcanic vents collapse after a sudden eruption, it makes a large circular depression, it may be a few kilometers in diameter.
Lava Plateau:
- When lava spread on the ground and makes an extensive highland plain or plateau is called the lava plateau. For example, the Deccan plateau is an example of a lava plateau.
Volcanoes mountain:
- When the volcanic lava from the mountain-like structure around the vent, it is called the volcanic mountain.
Mid-oceanic ridge:
A long narrow hill-like structure formed in the middle of the ocean by volcanic activities is called the mid-oceanic ridge. For example, there is about a 70,000 km chain of the mountain range in the Atlantic ocean.
Hot spring:
When molten magma stayed inside the crust but is very near to the surface that makes the surface water hot. This type of landform feature is known as a hot spring. It is the source of geothermal energy.
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