If horizontal layers of sedimentary rock have a vertical fault running through them, how might a geologist use relative dating to determine when the fault occurred?

Relative dating is a discipline of knowing the relative order of past happenings without actually knowing their absolute age, in other words, it is a just an estimated age. In this problem, relative dating could be use in determining when the fault occurred by seeing how many rock layers goes through and geologists match up rock layers over those distances.