This tracing the Atlantic coast tectites to the Laurentian Shield is an exciting new find, but the Firestone book tells a pretty clear story. Also, he shows an underwater map of Lake Michigan and says it shows 2 craters. However, looking at it carefully I feel I identify 3. Kind of like this: OoO. Looks a little like an ant body. Check it out, tell me if you see it too.
I know for a fact that New England was an impact site but there is some sort of strange connection to the Carolina Bays as well. Perhaps the wave of debris that caused the comet swept many different substances with it. Still, Carolina Bays were not under an ice sheet. The ice sheet did not extend that far south 12,900 years ago.