Question

what kind of mathematical tools do biologists and geologists really use?

Answer 1

A shovel

Answer 2

With out a doubt, these sciences would you probability theory or some sort of statistical tool developed from it, as would all sciences. Beyond elementary algebra/geometry etc then off the top of my head here is what I might think of for each area
Specific to biology:
Combinatorics (DNA base pairs?)


Geologists:
Exponential growth (Carbon dating)
Fourier Series (Maybe, specifically seismologists)

I dont know much about these subjects, I'm sure there's a lot more.