President Harding Rapid tumbles the water of the Colorado River at mile 44 and is located halfway, in river miles, between Lee's Ferry and Bright Angel Creek at Phantom Ranch.
President Harding Rapid may have been formed by the out wash of Tatahoysa Wash which flows into the U-bend from the south rim on the Navajo Indian Reservation. Most of the out wash material forms the delta on river left. But, the large boulder in the middle of the river creates most of this Colorado River Category 4 rapid. The scar and relatively fresh talus slope on the wall at the end of Point Hansbrough across the river is more likely the origin of the boulder in the river. Looking at the upstream end of the boulder you can see the large "pillow" of water that builds up against the barricade of the boulder. As the pillow water flows around boulder, the river froths into a rapid.
You can view this panorama, and many more of the Grand Canyon, including maps, and more complete descriptions at GCPano.org. You can directly view this panorama at url: https://project.gcpano.org/?enterAt=PresidentHardingRapid.pan
GCPano.org