An enormous dry waterfall in the middle of the Grand Coulee, eastern Washington state, USA. It was formed by the gigantic Spokane (a.k.a. Scabland, Missoula) floods during the last ice age, when a glacial dam in what's now northernmost Idaho would collapse periodically. The glacier, a tongue of the Cordilleran Ice Sheet, backed up glacial Lake Missoula into the Rocky Mountain trench, and so all that water would suddenly go sloshing across eastern Washington. The floods left behind the Channeled Scabland, a distinctive topography of buttes, coulees (flat-bottomed canyons), channels, closed basins, and enormous ripple deposits.