Extrusive landforms are formed from material thrown out to the surface during volcanic activity. The materials thrown out include lava flows, pyroclastic debris, volcanic bombs, ash, dust and gases such as nitrogen compounds, sulphur compounds and minor amounts of chlorine, hydrogen and argon.
Cinder Cones:
- It is of low height and form of lava and other pyroclastic materials.
- Due to gravity it piles up in large no.
- It consists of steep straight sides and a crater at the top.
Conical Vent and Fissure Vent
- Fissure Vent: A narrow, linear vent through which the magma comes out without any explosion activity is known as the Fissure Vent. These are commonly found in Shield type Volcanoes.
- Conical Vent: A narrow, cylindrical vent through which the magma erupts during an explosion is known as the Conical Vent. These are commonly found in Composite type Volcanoes.
Composite Type Volcanic Landforms
- The Composite type volcanic landforms are the conical type landforms.
- Along with Lava or Igneous rock, a large amount of pyroclastic material and ashes can be found on the surface of this landform.
- Mount Fuji, Mount Vesuvius, Mount Stromboli are examples of Composite type volcanic landforms.
Caldera
- Sometimes after the volcanic eruption, all the magma present inside the volcano erupts out creating an empty chamber below the earth’s surface.
- This leads to the collapsing of the volcanic material above into the volcanic chamber.
- This forms a hollow tube-like shape called the Caldera.
- It also appears as a Caldera lake when the rain waters or melted snow gets accumulated in it.
Crater
- An inverted cone-shaped vent through which the magma flows out on eruption is called the crater.
- An inactive crater appears as a bowl-shaped depression.
- It also appears as a crater lake when the rain waters or melted snow gets accumulated in it.
- Lake Toba is the largest Crater Lake in the world.
Read Also: Location Of Volcanoes
