When metamorphic rocks undergo pressure, how are they changed?

Question

When metamorphic rocks undergo pressure they are changed, but how are they changed? Do they become fragments of rocks? Doesn't that mean that the difference between sedimentary rocks and metamorphic rocks (when talking about fragment rocks) is that sedimentary rocks undergo weathering, which makes them fragments and metamorphic rocks undergo immense pressure which makes it into fragments?

Answer 1

First look at the rock cycle. A rock that undergoes heat or pressure becomes a metamorphic rock. Ground rock due to erosion becomes pebbles and sand. Pebbles and sand under pressure becomes sedimentary rock. Thus a metamorphic rock under pressure just becomes another metamorphic rock. To become a sedimentary rock it would have to be come sand through erosion first.

Answer 2

Typically when Metamorphic rock undergoes great pressure (and heat) it melts back into magma. So it doesn't really fragment, as much as melt.

Now it is important to know that if the heat is not high enough to melt the metamorphic rock, it can cause it to become a different type of meta rock, or just stay the same, as meta rocks are formed from great heat and pressure.