Co-author Anthony (Tony) Spencer standing on the Garbh Eileach Formation. The rocks record a gradual transition from the warm tropical world of the Tonian period into the snowball Earth of the ...

of the Port Askaig Formation on Garbh Eileach, the largest of the Garvellach islands. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert!