Giant kettles and a glacial erratic

"Plunging and swirling water of a river drills holes in the rock. Pot-holes are also drilled by the streams which drop through wells from the top to the bottom of a glacier. Falling hundreds of fee, the streams acquire great force and are able to excavate pits of astonishing size. At Cohoes, N.Y. are several which measure from 10 to 30 feet in diameter, and these held ponds and swamps after the glacier which made them had disappeared..."

"If we dig through the subsoil to the bed-rock, we shall often find the latter scratched in the same way, or even deeply grooved and carved into fluting's and the folding. The glacier, shod with stones at its base, drags these over the bed-rock, and thus both the moving fragments and the floor over which they move are polished and graven..."

Text and photos from the Flickr photostream of the Oregon State University Archives.