Tapeats Creek / Kanab Creek Loop Professional Review and Guide
"This eTrail is a detailed description of an adventurous loop through the Grand Canyon backcountry. Here is an excerpt from this eTrail's route description. "Surprise Valley, and the smaller valley and dry lake bed that you crossed earlier in getting to Deer Creek, represent a spectacular geological event.
According to Ford, Huntoon, Billingsley, and Breed (see the article “Rock Movement and Mass Wastage in the Grand Canyon” from the book Geology of the Grand Canyon), they are the result of a huge rotational landslide or slump. Visualize a segment of Canyon wall, from the Bright Angel Shale on the bottom to the Esplanade on the top, that is 0.5 to 1.5 miles wide and 2,000 feet thick, extending from the Thunder River on the east to Cranberry Canyon on the west. Suddenly this hunk of wall slips on the shale, breaks loose from its moorings, and rotates, with the bottom portion moving out and away as the top portion falls."