At mile 226, Diamond Creek enters the canyon, marking the takeout point for most white-water trips. The wide beach at the edge of the river is also used as a put-in for rafting trips managed by the Hualapai tribe as well as for private groups that have reserved a “Diamond Down” trip to raft the canyon’s remaining 54 miles through Lower Granite Gorge. The Diamond Creek Road climbs 16 miles from the river to Peach Springs on the Hualapai Reservation, a rugged scenic route.

John Wesley Powell’s party camped above the rapids at mile 239 in late August 1869. Weary, tattered, and disheartened, the men had opened their last sack of flour two days earlier. Several believed the rapids would be impassible. The next morning, three crew members left the expedition, and Powell named the roiling water Separation Rapids. Below it, the canyon widened, and the river became quieter.

Two days later, the six remaining expedition members reached the mouth of the Virgin River and nearby Mormon settlements. Only later did they learn that the three men who left were murdered. (The exact fate of the men is still unknown. Though Shivwits Indians have long been blamed for their deaths, canyon historians have also made convincing arguments that the murderers were Mormon settlers.)

At mile 276, the Grand Wash Cliffs mark the geographical end of Grand Canyon and the start of the basin-and-range topography of the Mojave Desert. The boundary between Grand Canyon National Park and Lake Mead National Monument lies just beyond. The waters of Lake Mead (impounded by Hoover Dam) slow the river’s current after Separation Rapids.

Long-term drought in the Southwest has severely impacted Lake Mead’s water levels, evident by the white “bathtub ring” that rises high above the surface of the lake. Sustained drought left the takeout point at Pearce Ferry high and dry, and for several years river runners had to continue on to busy South Cove beach to de-rig. In 2010 the Pearce Ferry Road was extended another two miles to the changed waterline, a $1 million project that once again allows river takeouts.

Not far from Pearce Ferry, the Colorado’s currents scoured—or superimposed—a new channel through the lake’s sediment deposits, resulting in new rapids with a nasty hole that has been known to flip rafts. Pearce Ferry Rapids, also known as Superimposition Rapids, is yet another example of how the canyon and river are constantly changing over time.