USGS Earth Science Photographic Archive digital file: hjk00778
On the First Expedition (1869), Powell named the region downstream of the Dirty Devil River, Glen Canyon -- named for the abundance of coves, alcoves, and grottos along the canyon and side streams. The gradient of the river lessened downstream of the Dirty Devil River, giving a much-need reprieve to the trials experienced in Cataract Canyon and later in the Grand Canyon. Before being flooded by the reservoir, the passage of Glen Canyon extended about 150 miles downstream to Lees Ferry.
