The sea level rose more than 120 meters in the last 20000 years, so it won't necessarily be that short distance, but I think at least it should be easy to calculate where to look.
An area with a half % slope could have an entire city below the waterline.
I think we're going to find that much like central and parts of South America, the extent of civilization has been vastly underestimated because Nature has covered over it.
Yes, even more recently the entire space between England and continental Europe used to be connected landmass, Doggerland [1]. It was home to Mesolithic people just 8,200 years ago.
I think we're going to find that much like central and parts of South America, the extent of civilization has been vastly underestimated because Nature has covered over it.