Final answer:
The first ice age was dated by combining radio-isotopic dating, leveraging isotope half-lives, with the principle of relative dating to find the sequence and age of geological events.
Step-by-step explanation:
The first ice age (Gowgandan Glaciation) was dated by combining radio-isotopic dating techniques with the principle of relative dating. Radio-isotopic dating involves using the half-lives of isotopes to estimate the ages of geological artifacts, a process that assumes no daughter atoms were present when the rock formed and that the rock or mineral was a closed system since formation. Absolute dating is the method utilized to determine the numerical age of a rock, where radioactive isotopes measure the decay of parent isotopes into daughter isotopes, providing an approximate age in years. Relative dating, on the other hand, establishes the sequence of events without a precise numerical age. By combining these techniques, geologists can understand not just the sequence of geological events, but also assign approximate ages to those events.