Few places enable you to discover geological forces at work as much as here. The "falls" are in fact a chasm some 400ft in height which has been dug out of the volcanic bed of the Columbia Basin. Thousands of years ago, floods during the Ice Age sculpted this landscape: the waters of the prehistoric Lake Missoula periodically penetrated the ice to disgorge billions of litres of water into the Pacific, in so doing moulding the landscape of the Columbia Basin.