Several times over the past two million years, vast Ice Age glaciers plowed south from Canada and dug out the steep-sided valleys that now hold Cayuga Lake and the other Finger Lakes. Since the most recent glacier melted away 12,000 years ago, Buttermilk Creek has cascaded down the steep east wall of the Cayuga Valley and slowly eroded the gorge from which the falls emerge. Floods wash away fallen rocks as well as soil and stones from upstream, scouring the gorge as they sweep through. Debris carried from the glen accumulates in the lake valley. Frost weakens rock on the surface of the gorge walls, and loose rocks eventually fall, widening the gorge.