When rocks are compressed, it can create fault lines. These fault lines are typically where a lot of earthquakes happen. The San Andreas fault line in California is a good example of that. When a fault line is rubbed the wrong way or pushed wrong, earthquakes happen. Sometimes, these earthquakes are soft, and sometimes they’re so destructive they make the news.
There is another thing that can happen when rocks are compressed. They can fold in on themselves. When rocks fold, they just become a folded rock. These are interesting in themselves because folded rocks are rare to see on the surface. The compression strength needed to fold a rock is only available under ground, where the tectonic plates are.
