Batholith
Topic: Interior of the Earth: Earthquakes, Volcanoes and the Layered Earth · NCERT: Class 11, Ch 3 "Interior of the Earth"
Meaning
A batholith is a very large body of magma that cooled and hardened deep inside the crust. It is usually granite and is often shaped like a dome, reaching several kilometres deep. It is really an old magma chamber (an underground pool of molten rock) that has set solid. Because it cools slowly underground, it forms coarse-grained rock. We see a batholith only after erosion strips away the rocks above it. It is an intrusive landform, which means it formed inside the crust, not on the surface.
Example
Many of the bare granite domal hills of the Karnataka plateau are exposed batholiths or laccoliths. Erosion removed the rocks that once covered them.
Don't confuse with
- Laccolith: smaller, with a flat base, and fed from below by a pipe. A batholith is far larger and goes down very deep.
- Lopolith: shaped like a saucer that dips down in the middle, not like a dome.