Re:Three Points (Score 1)

I had occasion to visit Alaska this last summer, and one can walk up to some of the glaciers and see the markers on rocks showing where the front of the glacier was in, say, 1973. Glaciers are always moving, and they are generally fed by ice fields. The rate of retreat of a glacier is dependent on how quickly the ice field grows and how quickly the face calves.

Glaciers advance more slowly in the winter, because everything is frozen, if anything I might expect the seasonal front of the glacier advance further during the summer.