J. David Rogers'
Grand Canyon Research
Granite Gorge Toppling Studies

Our research camp was situated on a tiny spit of sand in the heart of the Canyon’s Granite Gorge, at Mile 83.85, just upstream of Clear Creek.  From here we worked on mapping the massive Clear Creek topple complex, a short distance downstream.

Aerial oblique view of the mouth of Clear Creek, where it meets the Colorado River at Mile 84. This area was the focus of my field studies in the summer of 1978, mapping toppling failures in the Vishnu Schist. This picture was given to me by Luna Leopold and it was taken in June 1965 during the USGS-WRD channel survey, when the flow was maintained at 48,500 cfs.

Dave Rogers (right) and Professor Jim Mitchell surveying toppling failures at Clear Creek in the Granite Gorge of the Grand Canyon in June-July 1978. We surveyed the toppling complex using terrestrial photogrammetry with surveyed points of fixity.

Small flexural topple that we noted some distance up Clear Creek, not part of the 140,000 cubic yard topple we mapped.  Toppling is triggered from the slope toe headward, with strain accumulating as an integral function.  In this manner, distortion increases upslope, but the failure is almost always triggered by toe excavation.

Main Clear Creek topple complex, looking in the opposite direction (south) as the previous photo.  A basal detachment surface is seen in the foreground. The toppled blocks above this surface slid downhill, leaving a bare slope inclined at 35 degrees.  Note the dilatent nature of the toppled mass in the background, with abundant voids and fissures.

Page from my sketch pad illustrating the contrast between flexural topples (at left) and buckling failures (at right) observed in lower Clear Creek. We also managed to score a C-14 sample from the indurated terrace gravels about 30 feet above the channel (shown above). Unfortunately, it dated at > 40 ka.

Buckling failures noted on the eastern wall of Clear Creek, in the steeply-inclined Vishnu Schist.  They looked like piles of cord wood, stacked one upon another.  I included a rigorous analysis of these buckling failures in my PhD dissertation.

Pedestrian suspension bridges at the mouth of Bright Angel Creek near Mile 87.5.  Zoroaster Temple dominates the skyline.  The darker Kaibab Bridge in the background was built in 1928 while the silver Bright Angel Bridge in the foreground was completed in 1965, as part of the water supply system extending from Roaring Springs to the South Rim. I was pretty excited when I reached this spot during my first backpacking trip off the North Rim in June 1971. I was entranced with the rafters passing by and vowed to return some day on a raft.

On the June-July 1978 trip we noted another toppling complex developed in the Vishnu Schist on the western side of Travertine Canyon, near River Mile 95.5. This has never been mapped or analyzed.

Approaching Waltenberg Canyon (coming in from the right, at Mile 112.15) we noted yet another toppling complex developed in the schist, continuing along the opposite side of the Inner Gorge. This is the largest of three complexes noted.

Field sketch of the toppling complex shown above.  We had not budgeted time to study the topples at Travertine or Waltenberg Canyons and as far as I am aware, no one else has studied them in the interim since.

Questions or comments on this page?
E-mail Dr. J David Rogers at rogersda@umr.edu.