At what point does a frozen river become a glacier?

A frozen river does not become a glacier. A frozen glacier ( tautology!) can become a river. When snow keeps falling pile upon pile in one place, and less of it melts than falls, the incubation of a glacier has begun. As soft now piles up, the lower layers are compressed and begin to harden. read more

My point is that ice (whether in a frozen river or in a glacier) is still a fluid and they keep moving because of their weight. – arkaia Feb 3 '15 at 4:05 @Fred Imagine a river made up of an extremely viscous material that flows at incredibly slow rates. read more