[Illustration: BOWKNOT BEND, of Green River, looking east from west end of narrow intervening saddle. Upper photograph was taken by E. O. Beaman on September 10, 1871, during second voyage of Major John Wesley Powell and his party. Lower photograph was taken from same camera station on August 19, 1968, by Hal G. Stephens, U.S. Geological Survey, on expedition led by E. M. Shoemaker to recover camera stations of the 1871 voyage and rephotograph the scenes to record changes during the nearly 100 year interval. Note that almost no changes occurred in the bedrock, or even in the loose rocks, but that considerable change occurred in the vegetation along the river. Although salt cedar (tamarisk) had been introduced into this country from the Mediterranean area long before 1871, it had not yet spread to this area, but the bare islands shown in the earlier photograph are covered by salt cedar in the 1968 photograph. (Fig. 62)] [Illustration: Figure 62, lower image] All travelers down the Green River embarking from Green River, Utah, or above, were impressed with Bowknot Bend (fig. 62), so named by Powell and his men (1875, p. 54) near the beginning of Labyrinth Canyon, which they also named for its deeply entrenched meanders. The upper photograph in figure 62 was taken by Beaman on September 10, 1871, looking eastward from the west end of the narrow saddle separating the upper and lower reaches of the river; the lower photograph was taken from the same point on August 19, 1968, by Hal G. Stephens nearly 97 years later. Although there are changes in the vegetation, as described in the caption, there are virtually no visible changes in the bedrock. Nevertheless, the distant future will likely see a breakthrough, whereby Green River will shorten itself by about 7 miles (Herron, 1917, pl. 15C). It is interesting to note that the vertical cliffs of Wingate Sandstone in and west of Bowknot Bend are only a few hundred feet above the river, whereas, because of the gentle northward dip of the beds and the gentle southward grade of the rivers, the Wingate cliffs are more than 2,000 feet above the two rivers at Grand View Point and Junction Butte, at the southern tip of Island in the Sky. At the mouth of Horseshoe Canyon, about 3 miles below Bowknot Bend, we pass a large rincon where the Green River shortened its course by about 3 miles. Some idea of the rincon’s antiquity is gained from the facts that the river is now some 350 feet lower than at cutoff time, whereas Bowknot Bend (fig. 62) has shown no visible deepening in 97 years. This rincon was not noted by Powell or other early voyagers, seemingly because they did not happen to climb the banks at this point, but it is quite noticeable on modern topographic maps and on aerial photographs. This rincon and Jackson Hole along the Colorado River may be as old as late Tertiary (fig. 80).