When Earth entered one of its most extreme cold phases, about 700 million years ago, salt may have been the factor that intensified the transition to the so-called "Snowball Earth". It is believed that, during the Precambrian, the planet was covered by an ice layer between 2 and 2,000 meters thick.
During the phases known as "Snowball Earth", ice extended over much of the planet's surface, possibly covering it entirely. This glaciation has been mainly explained by the ice-albedo feedback mechanism: bright ice reflects more sunlight than dark sea water, which reduces temperatures and favors the formation of more ice.
The "Snowball Earth" theory proposes that Earth was covered in ice several times between approximately 750 and 580 million years ago. Geologists explain this theory through glacial sediment deposits, which constitute traces left in rocks.
