The Dry Falls in central Washington have been cut into the Miocene Columbia River Basalt Group that flowed from Idaho to the Pacific Ocean in one of the greatest outpourings of lava in the Tertiary. The falls themselves are nearly three times as high as Niagara Falls and formed during massive floods in the Pleistocene as dams made of glacial ice failed upstream, releasing huge floods that carved the channeled scablands across parts of the Columbia Plateau.