Was it a gradual transition from dry land to ice? Was it a steep wall?
I don't think we have any paleolithic archaeologists on this sub (at least from looking at the list of flaired users), and they would be best qualified to answer this question.
You might want to cross-post with /r/geology, /r/askscience (under earth science), or under /r/archaeology.
hi.. as mentioned, this is a question for earth scientists, but you may be interested in a previous thread