Magma
Topic: Interior of the Earth: Earthquakes, Volcanoes and the Layered Earth · NCERT: Class 11, Ch 3 "Interior of the Earth"
Meaning
Magma is molten (melted) rock found in the upper mantle and the crust. It comes mainly from the asthenosphere, a weak, partly molten zone in the upper mantle down to about 400 km. Magma is lighter than the solid rock around it, so it rises. It collects in magma chambers under volcanoes. If it cools inside the crust, it forms plutonic rocks such as granite. Once it moves towards or reaches the surface, it is called lava.
Example
Under Barren Island in the Andaman Sea, the Indian plate slides down beneath the Burma microplate. Magma forms there and rises to feed India's only confirmed active volcano.
Don't confuse with
- Lava: the same molten rock once it moves towards or reaches the surface. Magma stays underground.
Related concepts
- Volcano
- Lava
- Pyroclastic material
- Active volcano
- Shield volcano
- Cinder cone
- Composite volcano
- Caldera
- Supervolcano
- Flood basalt province