About 15,000 years ago—Valley glaciers moving west up the valley
It is very late in the Ice Age and the once great Hudson Valley glacier is confined to the lower reaches of the Hudson Valley. It's much reduced by melting but it is still sometimes capable of a substantial advance. We are witnessing one of those right now. Passing from our left to our right is the Catskill Creek tongue of ice. It is something of an upside down Alpine glacier. Shoved from behind, it is slowly grinding its way up the valley of Catskill Creek. It creeps by, too slowly to observe, but we hear a cacophony of cracks, pops and snaps as the brittle ice fractures from the movement.