The geologic evidence that much of north america and europe was covered with glaciers until about
10,000 years ago provided evidence that

Civilization of any substantial size did not arise until at least that time of 10,000 years ago. How gradually it actually was we can only guess. However this is the time period where the Stone Age (Neolithic) showed evidence of division of labor (a key indication of social structure) like hunting vs gathering, child rearing, and even art and history set in carvings.

One cannot begin a civilization on a ground that is a massively and densely packed ice mountain moving several inches a year (a glacier).

They formed the oceans.  as they melted water was formed and the water made the oceans