Missoula floods

The process has a name, plucking.

And on the scale of the Missoula floods, it was ferocious.

The water plucked out basalt columns by the thousands, by the millions, tearing channels into the rock, carving canyons in days that would take ordinary rivers ages to make.

These channels are called coulees.

And on that floor, in the deep hollows at the base of the cliffs, there are lakes small and still reflecting the sky.

You're looking at the remains of a waterfall.

During the Missoula floods, water poured over this cliff in a single enormous sheet.

It was the largest waterfall that geologists know of in the history of the Earth, measured by the volume of water it carried.