How are frozen waterfalls formed?

When the environment is cold enough, two things happen: One, the flowing water, as it cascades over the falls, becomes in part a huge number of individual drops and droplets falling through air well below the freezing point of water. read more

Ice dams form across the slower-flowing portions. This, by the way, accelerates the accumulation of ice towers below those fast-running outlets. It is not true, by the way, that the waterfall freezes solid. If the watercourse has any flow at all, pressure will eventually build up and the water will escape somewhere. read more

Furthermore, since the water in a waterfall is continuously mixing, the cooling takes place uniformly over the entire waterfall, so it takes longer for any readily noticeable changes to appear. This means that, unlike still water (where you can easily spot frozen patches of water floating on the surface), if a waterfall begins to freeze, it will take some time before you actually notice the effects. read more

Waterfalls normally form in a rocky area due to erosion. After a long period of being fully formed, the water falling off the ledge will retreat, causing a horizontal pit parallel to the waterfall wall. read more

This means that, unlike still water (where you can easily spot frozen patches of water floating on the surface), if a waterfall begins to freeze, it will take some time before you actually notice the effects. read more

Waterfalls result when water flows down over hard rock that is on top of a softer rock. The soft rock wears away faster from erosion than the harder rock does. The soft rock erodes away below the harder rock, undercutting it. This causes the ledge to collapse and pushes the waterfall further back upstream. read more