Iceberg (IMAGE) University of Cincinnati Caption Researchers found evidence that Earth was not completely frozen solid during the Marinoan ice age 635 million years ago. Shallow, mid-latitude seas remained ice free, perhaps helping life persist. Credit Michael Miller Usage Restrictions None License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.