11. What do foliated and un-foliated mean in metamorphic rocks?

They are two types of metamorphic rocks which differ on the basis of formation and appearance.

Explanation:

Foliated metamorphic rocks are a type of metamorphic rocks which appear like layers which is caused due to heat exposure and pressure. They are formed due to high pressures. Examples are phyllite, slate, schist Non-foliated metamorphic rocks do not have such a layered appearance. They are formed due to low pressures and also because of contact metamorphism. This is why they are mostly called as hornfels. Examples are hornfels, marble