Originally known as Superimposition Rapid, Pearce Ferry Rapid gives us a sped-up view of geology right before our eyes. Before the reservoir, there wasn’t anything here of significance. As Lake Mead filled the lower reaches of the Colorado River, the current slowed which caused the river’s sediment load to drop out, which is a process known as sediment deposition. (Picture the effects of a kite with no wind.)
Then the reservoir experienced a drawdown, effectively receding the reservoir and unveiling a river once again. The spot at Pearce Ferry Rapid uncovered a knickpoint, as the river had cut a new path downstream through this area and was also now running into the deposited sediment and was once again, picking it up, literally creating something brand new in a very short period of time.
What’s been left is an unrunnable Class X for rafts. The river constricts and makes a jarring right hand turn. The turn and the constriction are fine, but the unavoidable overhead holes are not.
Exasperating this problem was that the original takeout was downstream of this point. With the rapid forming in 2007, river runners were forced to take out upstream at Diamond Creek. Needing a solution, the NPS eventually spent approximately $1,000,000 to extend the road two miles and add a new takeout just above the rapid.
For further reading, this write-up by Durango Bill is excellent.