A slot canyon between mile 134-137 downstream from Lee's Ferry in the Grand Canyon. The walls are of a sedimentary drainage 'slot canyon', with a large boulder wedged in the walls.? Such defiles claim lives too regularly in the Canyonlands of Utah, where storms over the horizon can send torrents of water 'out of nowhere'. As the Colorado River descends from an elevation of about 3100 feet at Lee's Ferry, some 280 miles to Lake Mead (1200 feet); it is also a journey back in time, cutting throug