What is the Cryogenian Period?
The Cryogenian period is a geologic period from 850 million to 630 million years ago. It occurred before the Ediacaran Period and after the Tonian Period, and is part of the much longer Proterozoic era, meaning “era of primitive life.” In Greek, Cryogenian means “ice origin.” Although ice did not really originate with the Cryogenian period, it was everywhere, and glaciers may have extended from pole to pole. A human transported to that time might have been able to ski all the way around the Earth. The Cryogenian period is one of the few geologic periods in the last billion years to be named after a substance or concept (in this case, cold) rather than a modern area where fossils from the period are found (for instance, the Jurassic is named after the Jura Mountains). During the Cryogenian period there were at least two major ice ages, and perhaps as many as four. Glacial deposits in the Cryogenian strata at equatorial paleolatitiudes (specifically, the Congo and Kalahari cratons) has l
