Question

How do geologists classify metamorphic rock?

Answer 1

Geologists look at the layers (foliated) and grains (non-foliated) within a rock to identify it as metamorphic.

Explanation:

The prefix meta- means "after." A good way to remember metamorphic rock is to call it "after rock." Metamorphic rocks are born from the transformation of existing rocks. The original rock undergoes chemical changes with heat and pressure, thus creating a new rock with mixed grains and layers.

Rocks with grains (i.e: quartzite) and with layers (i.e: schist) were once part of other earthly materials.

Geologists try to find layers and grains that can trace back to other rocks.