What does pressure make rocks become?

Answer The atoms in rocks rearrange to form denser minerals. The combination of heat and pressure may cause the minerals in the rock to separate into layers.

Answer Pressure squeezes out any remaining water that may be left in the metamorphic rock and minerals that have water as part of their structure are changed chemically to minerals that do not require water as part of their structure. The metamorphic rock will then have become a higher grade metamorphic rock possibly containing garnet, a non-hydrous mineral.