Jackson Hole Abandoned Rincon

Almost since I moved here roughly 13 years ago there has been a group of geologists exploring and studying Jackson Hole. Let by Sherman Young I've enjoyed listening to the learning curve in their extensive time in Jackson Hole. They finished their report just prior to the movie shoot that occurred here and I just ran out of time to go through it properly. It's so well written.

Sherm has given me permission to quote some of their report. I'd like to start with parts of the first paragraph referring to Jackson Hole, throw in a couple maps, and the final two paragraphs. Here we go.

"In the landscape near Moab, Utah, there is a vestige from hundreds of thousands of years ago that tells a story of the evolution of the Colorado River -- the Jackson Hole Rincon, an abandoned bedrock meander.
    The Jackson Hole Rincon is unique.  It is the only one of many bedrock meanders on the Colorado Plateau whose remarkable record of preserved river deposits has allowed study of the formation, evolution, and abandonment of the rincon. Quantification of these events will be important for an understanding of other dynamics in the region related to erosion, salt tectonics, and the overall evolution of Utah’s Canyonlands.  In pursuing an understanding of these events, questions arise concerning the paleoclimate at the time the meander neck breached and the rincon came into being.  For example, it appears that the abandonment of the meander coincides with Pleistocene paleoclimate changes that resulted from orbital forcing (Milankovich-cycles).  Also, speleothem (stalactite and stalagmite) studies from caves of the southwestern United States support a close relationship between this region’s evolution and global events.  What relationship if any, do these orbital and global events have to the Jackson Hole Rincon, or how it came to be?  Hopefully an examination of the abandoned meander at Jackson Hole will allow geologists to explore these matters and find answers to these and other questions."

"   "The Jackson Hole Rincon near Moab, Utah, is unique among the many rincons on the Colorado Plateau in that its remarkable record of preserved river deposits has allowed for the study of its formation, evolution, and abandonment.  These studies show that the abandonment of the rincon occurred approximately 128,000 years ago.  Just prior to that time, a massive melt water event occurred during which the great majority of global glacial ice melted over the course of a relatively short period of time.  While it is attractive to think that the breach of the meander neck and formation of the rincon may have been the result of overspill of the meander neck due to flooding from this enormous melting event, optical luminescence dating and study of incision rates at the rincon suggest that it is unlikely that deglaciation flood-waters in the paleo-Colorado River over-spilled the meander neck, leading to formation of the rincon.
    On the other hand, a smaller pulse of incision at about the same time, which may have undercut the outer bank/cliff of the river, is consistent with the presence of the rock avalanche shown on as C5 on Figure 7.  The rock slide may have impounded the paleo-river enough to initiate breach of a low bedrock neck.  At present, this appears to be the most plausible explanation as to how the meander neck was breached and the Jackson Hole Rincon was formed."