hydrologic cycle

Image courtesy USGSA team of geologists from China and the United States, including two from WUSTL, report evidence of at least three ice ages occurring between 750 and 600 million years ago.Glaciers reached Cape Cod, Massachusetts, in the most recent ice age about 20,000 years ago. But much harsher ice ages hit the Earth in an ancient geological interval known as “the Cryogenian Period” between 750 and 600 million years ago. A team of geologists from China and the United States, including two from Washington University in St. Louis, now report evidence of at least three ice ages during that ancient time.