Another kind of rock is called metamorphic. Metamorphic rock was originally some other type of rock that was gradually changed or metamorphosed by high temperatures and pressures often deep beneath the surface. Like intrusive igneous rocks, these bodies are also irregularly shaped. If we see such rocks at the surface, we know that the area was uplifted, and a tremendous volume of rock that once lay on top of this schist must have been eroded away. [North Mountain phyllites. Rocks have been squeezed from forces directed left-right in the photos.]