Why do geologists need so much math?

To be honest, it is basically a hoop you have to jump through to get a degree in just about any physical science. However, many geology applications use calculus, like crystallography, and of course geophysics. I do not see any need for it in stratigraphy or sedimentology. You probably would need a lot of statistics as well as computer skills. But, you never know where you will end up. You could start off in one direction, as you stated, and end up doing something very different.