Re: Snowball Earth was typical
There was a documentary on BBC a few months ago about the Snowball Earth. 700 Million Years ago, there was such a condition. Before that, life was monocellular; after that, it multiplied and differenciated. Snowball Earth was a completely frozen planet, all covered with ice but without any clouds. Life could also wait below the ice as it was demonstrated that sunlight was enough to keep the organisms alive underneath the ice crust. Why did it change? Because underneath the ice coat, volcanism went on and burst the greenhous gases which warmed the planet and life blossomed.
Raoul