Mysteries in the Navajo Sandstone
Anyone who spends much time hiking across Navajo Sandstone will begin to notice mysterious shapes and anomalies in the normal wind-deposited layers.
Navajo Sandstone in Arches National
Park
This section of Flameskimmers.com describes some of the things we've observed and recorded through years freestyle hiking across this beautiful and elegant landscape. (Most of our hikes are in and around Arches National Park.)
For years we've marvelled at what we've found eroding under the desert sun, and for a long time we had no idea what we were looking at or how it had formed. None of the phenomena we observed were mentioned in the NPS brochures or the natural history guides we bought at the national park visitor centers at Arches and Canyonlands. The only book we could find that described the same things we observes was Navajo Sandstone A Canyon Country Enigma, No. 55 in the Canyon Country Publications series, by F.A. Barnes.
- Black Stuff and Red Stuff. There are hard black and red layers, columns, and swirls embedded in between the wind-deposited layers, and also independent of the original surfaces of the ancient dunes.
- Hard balls. Balls are eroding by countless millions from the sandstone matrix. Sometimes they're made of Black Stuff. The geologists call them "concretions"; locals call them "Moki marbles". But what caused them to form?
- Origins. Where did all that sand come from in the first place? Nobody seemed to know. The Navajo extends from Nevada through northern Arizona, Utah, western Colorado, and southern Wyoming. It is 2500 feet thick in Zion National Park, but narrows to only a few feet in thickness on its eastern boundary. That's a lot of sand.
- Upper Interface. The Navajo – Dewey Bridge interface is as flat as a pancake. What happened here?!
- Potholes. Why do they form on top of exposed fins and humps high above any wash? Why are the bigger ones full of water even in the height of summer?
- "Upside-down Desert". The Navajo in southeastern Utah contains numerous flat-topped "mesas" formed from harder layers of what appeared to be limestone and tuffa. These lenses of mineralized stone were deposited by water. The Navajo was supposed to be a "Sahara-like desert", a sea of sand stretching for thousands of square miles on the ancient western shore of Pangea. So where was all the water coming from that filled the playas? How did the water last long enough to support a robust food chain with 3-toed theropods (ancestors of the dinosaurs) at the top? The playas are full of track impressions and fossils.
- Petrified wood. Petrified wood is found near the margins of playas. Again, how were the trees able to survive in a Sahara-like desert? Wouldn't they die when the playa water dried out?
- Stromatolites. This is the most mysterious enigma of them all. Fran Barnes was the first to identify stromatolites in Navajo Sandstone, just before he passed away in October 2003. Stromatolites have recently been discovered (2006?) in Capital Reef National Park. I have just identified some of our own discoveries in Arches National Park as stromatolites. The Navajo paleo environment was primarily an arid desert. What were stromatolites doing growing there?!
– by Mary Ecsedy, 6/23/2010, Draft in-progress