How the harsh, icy world of Snowball Earth shaped life today
Lead: On remote outcrops in the Garvellach islands off Scotland’s west coast, a continuous rock sequence records a global turning point: between about 717 and 635 million years ago the planet plunged into repeated, near-global glaciations. These Cryogenian events — chiefly the Sturtian (beginning ~717 Ma, lasting ~57 Myr) and the Marinoan (about 645–635 Ma) … Read more