All the World in Ice
In Norse myth, the world began in ice, and only as it began to thaw was the world we know truly created.
Interestingly enough, there is growing evidence that Earth really did undergo several total glaciations, in which the world was entirely covered in deep sheets of ice that were broken only when volcanoes erupted under the ice, melting enough of it that sunlight could shine on darker surfaces and melt adjacent ice.
However, studying periods from so long ago is difficult, simply because very little of that era's rocks have remained unchanged enough to carry recognizable information from that period. However, here and there we can find bits and pieces that tell us enough of the conditions at that time that scientists can piece together what the Snowball Earth must've looked like.
Interestingly enough, there is growing evidence that Earth really did undergo several total glaciations, in which the world was entirely covered in deep sheets of ice that were broken only when volcanoes erupted under the ice, melting enough of it that sunlight could shine on darker surfaces and melt adjacent ice.
However, studying periods from so long ago is difficult, simply because very little of that era's rocks have remained unchanged enough to carry recognizable information from that period. However, here and there we can find bits and pieces that tell us enough of the conditions at that time that scientists can piece together what the Snowball Earth must've looked like.