Moab, Rivers and Geology

Last weekend found me back in Moab...go figure. This time I was attending the Moab River Rendezvous a get together created by Plateau Restoration, a group dedicated to protecting and restoring native habitats on the Colorado Plateau. The rendezvous was a chance for lovers of the plateau and its rivers to get together and learn more about the place, do a service project, see some phenomenal movies and have a blast while doing it.

I could not get away for the whole event, but Saturday afternoon and Sunday were lots of fun. Saturday afternoon, the keynote speaker Wayne Ranney discussed his newest book on Carving the Grand Canyon. The river runners in the room were held spellbound by his description of what lava falls would have looked like in the beginning. Later that night were some old home movies, taken by Grand Canyon river runners in some of the high water years in the 1950's before any dams were in place...it was a different world.

Saturday's field trip into Arches National Park was the highlight for me. We walked out Bloody Mary wash to fossil falls which is on the Moab fault. Slickensides and fossils on the same stop! We then drove into the park and spent most of our time looking at the salt valleys (collapsed anticlines) that were so instrumental in making the modern landscape we see today. There was lots of discussion looking at the orientation of the salt valleys and their relationship to the nearby laccolith mountains, the La Sals.

The Moab fault up close. This is called fossil falls as the (Honaker Trail, Pennsylvanian period) limestone on the left is just chock full of crinoid parts, horn coral and brachiopods.

Looking across the Colorado River towards the La Sal Mountains a 25 million year old igneous intrusion.
Looking across the salt valley into the fiery furnace. The salt valley is a collapsed anticline created by the movement of subterranean salt. The furnace is a maze of Entrada sandstone fins.
Not the best picture, but one of Utah's state emblems, Delicate Arch can be seen in the center of the image by its distinctive shadow. This view is also across the Salt valley collapsed anticline