JF Ptak Science Books Quick Post Part of the History of Lines series
In grazing "The Geology of New York City and Vicinity", a pamphlet by Chester Reeds and printed by the American Museum of Natural History (NYC) in 1926, I found these maps of the extent and thickness of the last glaciers in the region, and thought them quite lovely.
This was the southernmost lobe of the Laurentide ice sheet, a vast plain of enormous ice that covered most of North America, the last bit of which dissipated around 22,000 years ago. The maps reconstruct a bit of that glacial topography--the physical kind, not the one you'd experience walking around TriBeCa ina brown suit. Where the lines are closest together is the channel where the Hudson River would flow.
And the full map, one of three in the segment: