Thanks for the link, CK. It reminded me of chuckle I got when a woman added to description of property she wanted to sell that it contained an "esker path". A sly way trying to make a virtue out of fact much of the land was useless because of deep deposits coarse rounded gravel for which there was no demand.
This was material that had collected in a large crevasse, and eventually wound up in an irregular stream at bottom of the glacier fed by melt water. It is believed that the ice was a mile deep until it retreated about sixteen thousand years ago.
Interestingly, pollen studies have indicated that it retreated at about a quarter of a mile per year. No clue as to rate at which it had advanced.