This photo of Mount Sentinel, with part of the city of Missoula in the bottom foreground, shows what University of Montana geology professor David Alt described as "shorelines of Glacial Lake Missoula." The ice age lake created by ice dams in central Washington backed up water as far east as Montana. When the ice dams failed the massive lake surged toward the Pacific Ocean scouring and creating the area in Washington known as the "channeled scablands."
