Answer:
This is so cause ...
Igneous rocks are formed when the molten material cools and hardens
and
Metamorphic rocks form when they are subjected to high temperatures and the great pressure of the rock layers above it.
So most of these rocks are found beneath the earth''s crust
(I hope im right... this might not be the perfect answer... but this as close as I can get.. I hope it usefull for u )
