Geologic Time Scale
This is how the Earth may have appeared during the Marinoan glaciation about 650 million years ago, a period when snow and ice covered most, if not all, of the Earth's surface and oceans. In this view the southern and eastern hemispheres are dominated by glacier-covered land masses while the opposing hemispheres are frozen ocean save for a few areas of exposed liquid water, AKA refugia for the Earth's surviving soft-bodied multicellular organisms.
In addition to the 15 million year Marinoan glaciation which lasted from approximately 650 to 635 million years ago, there may have been a 60 million year "snowball" period (known as the Sturtian glaciation) which occurred between 720 and 660 million years ago, and perhaps several more before that going back to two billion years ago.
The causes of these snowball periods are unknown but may have been due to massive volcanic eruptions, massive meteoritic impacts (both resulting in global sun-reflecting ash clouds), or variances in the Earth's orbit.
Copyright © Walter B. Myers. All rights reserved.
[ Home | What's New | The Graphics | Information | Site Map | ]