Cleavage (geology)

Cleavage in geology is like a special way that rocks can break apart. It happens when there are flat planes in the rock where the molecules or particles are lined up a certain way. When something bumps into the rock, it doesn't break randomly, it breaks along those flat lines.

It's like how if you're playing with a block tower, you can't just smash the whole tower into pieces with your hands. But if you take a book and hit the tower along one of the flat sides, the tower will break apart along those flat sides because it's weaker there.

Cleavage is important to geologists because it can give them clues about how different rocks were formed and how they will behave under certain conditions. And it's also an example of how even really hard things can still have weak spots that are easier to break apart.