My son at the edge of Dry Falls, at the head of the Lower Grand Coulee in Eastern Washington this morning. Between fifteen and thirteen thousand years ago, glacial lake waters periodically spilled across ice dams at the south end of the Okanagan Lobe of the Cordellerian Ice Sheet and carved gigantic channels across the central part of Washington State. Water hundreds of feet deep roared over these 400 foot high cliffs, ten times the current flow of all the world’s rivers, and over a two thousand year period created what geologists call the largest known waterfall to have ever existed.