Some think so, advocating for the creation of a new epoch of time called the 'Anthropocene,' or the 'age of man', to indicate our domination over the earth. But how can we tell? Usually geologists decide that a new epoch or era has started once they figure out that something new has appeared in the rock record at a particular time. It could be dust from the comet that killed the dinosaurs, ash from a particularly epic volcanic eruption, or fossils that appear or disappear in bursts of evolution or mass extinctions. Up until now, we've been content members of the Holocene, a geologic epoch that started with the end of the last ice age.