Glaciers advanced and retreated a dozen times or more, damming Glacial Lake Missoula, bursting with gargantuan force, flooding areas 400 miles away, and shaping today's landscape in Idaho, Washington and Oregon. Glacial ice above lake level stood as tall as a 200 story building above lake level and rose 4 times as tall as Seattle's 605ft Space Needle. The total depth of ice may have exceeded 3,500 feet when reaching to the lake's rock bed. Only the mountains with peaks rising above 4,500 ft. in elevation would have been visible from the top of the glacier.