As to 'Layer or Mountain' - we could get into a little geology lesson here - the granite is a type of magma that cooled underground. ( I guess what may be in Texas could be called a Batholith if its really a large enough mass) - probably from subduction sometime in the past.

Take a look at the Sierra Nevada Mountains - they are composed of granite - a large batholith. over a period of time they are raised up due to faulting and uplift and just general erosion of the surrounding materials.

It wouldn't be called a layer particularily as it was a mass of magma that was moving up through the surrounding rock. Look at the definition of Pluton.

Canie

• Geologic Glossary