I'm quite sure the 'F' is a mistake, and the word is MIXTURE.
Answer:
Where is the picture? Can't answer without it.
It changes because when the 2 tectonic plates collide they form mountains and volcanoes.
Continental drift causes tectonic plates to either "pull apart" or "crash" into each other.
Plates that crash into each other either form mountains, or when one slides under the other (a subduction zone) volcanoes from.
You can study article about slope and speed
