Final answer:
Geologists use relative dating and absolute dating methods to determine the age of events on the geologic timescale.
Step-by-step explanation:
Geologists use two methods for dating events in Earth's history. The first is called relative dating, meaning how events relate to each other in time, or more plainly, they figure out the sequence of events (what came first, second, third, etc.). Relative dating has no regard for numerical ages. The second method is absolute dating, where geologists use radioactive isotopes to figure out the numerical age of a rock or mineral.