A waterfall probably existed beneath the  Main Ice Sheet that once covered the area more than 12 800 years ago, and the meltwater was under high pressure and smoothed the surface. The glacier itself probably contributed to the erosion, and sand, pebble, and cobbles frozen to the sole of the glacier acted as a gigantic sand-paper. The surrounding cobbles and boulders are probably rock falls from the slope above. Beneath is a detail-photo of the smoothed rock-surface.