C.3. Volcanoes And Volcanic Landforms
- A volcano is a place where gases, ashes and/or molten rock material – lava – escape to the ground.
- A volcano is called an active volcano if the materials mentioned are being released or have been released out in the recent past.
- The mantle contains a weaker zone called asthenosphere.
- The material in the upper mantle(asthenosphere ) portion is called magma.
- Once it starts moving towards the crust or it reaches the surface, it is referred to as lava.
- The material that reaches the ground includes lava flows, pyroclastic debris, volcanic bombs, ash and dust and gases such as nitrogen compounds, sulphur compounds and minor amounts of chlorine, hydrogen and argon.
- Volcanoes are classified on the basis of nature of eruption and the form developed at the surface.