[RightWhale]

Lakes here in the permafrost develop from sinkholes and fill in from dust and various living things. That crater appears to have been covered to considerable depth and the soil is now in Indiana after the glacier melted leaving bedrock. It has been exposed for much too short a time for erosion or vegetation to do serious work.

[Hegemony Cricket]

"...the soil is now in Indiana..."

I'll go look in my yard...