My theory is that the Carolina Bays were formed when gigantic chunks of ice were thrown out of the ice sheet by impact, and then melted. If I remember correctly, the book SC posted said something about CB type shapes found elsewhere, and that lines along the long axis of the oval mostly pointed toward Lake Michigan. Since there may have been more than one boloid strike, other bays could also have been produced with a different axis orientation.
Can you imagine what the tsunami must have been like?