Don't know if you've ever been to Central Park in NYC but if you have you'll surely remember the many rocky outcrops that are seen there.I've seen documentaries which say that those outcrops represent irrefutable proof that Manhattan was once covered by a glacier that was hundreds of feet thick.
Geology was a required course in 8th grade in upstate NY 50 years ago. We took a number of field trips to see glacial striations on rock outcrops as well as the glacial terminal moraine at the end of Cayuga Lake. I still remember being impressed by that and the fact that there used to be a MILE thick ice sheet right on the spot we were standing. When you think about it, 11,000 years ago really isn’t that long ago.