Friday, May 7, 2010

A day near Mt. Taylor

I got to spend a day this last week near Mt. Taylor, a composite volcano north of Grants, NM. It was active approximately 3.3 to 1.5 million years ago, and overlies Cretaceous Interior Seaway sediments. The OF-GM-186 for the area is unavailable from the New Mexico Bureau of Geology and Mineral Resources at this time, so its difficult for me to tell you which of the Cretaceous sediments are exposed in my photos, but I do assume they include the Mancos Shale in one of its forms.
Mt. Taylor is sacred to most of the Native American tribes and pueblos in the southwest and much of the surrounding mesa-tops and the mountain itself have recently been designated a traditional cultural property, requiring both tribal and State Historic Preservation Officer consultation for federalized projects.
This designation makes uranium exploration and development more complex on private, state and federal lands. The price of uranium has risen in the last few years, making extraction more economically feasible, but the cost of environmental evaluation, permitting, and consultation must be absorbed into development costs. Though exploration companies may balk at the process, it's the cost of doing business in the area.
As an aside, the uranium source is mostly in the Jurassic Morrison and Todilto formations (Grants Mineral Belt), which do not surface in the immediate area where I was (though there has been considerable exploration, mining and milling on the east side in the past).

Photo 1 is a dome/neck on the southeast side of Mt. Taylor, near Seboyeta.

Photo 2 is the scenic potty view through the junipers. Basalt-capped Chivato Mesa, with Cretaceous sediments below.

I don't have detailed geologic maps for the area (see above), but I'm presuming this is Pt. Lookout with Mancos below?

Looking south from atop the mesa.

Looking east, with the Sandias in the distance.

I used the below websites and the 1991 Field guide to geologic excursions in New Mexico and adjacent areas of Texas and Colorado (Bulletin 137, NMBMMR) as references.

Wednesday, May 5, 2010

Palm Canyon, CA, June 2005

I don't have a lot of time, but want to post some pix from a hike up Palm Canyon a few years back. I haven't the resources to really say too much about the geology, either, as my references for the area are still packed away. This will have to do. Pictures courtesy of MK, 2005.

One of my favorite places in desert SoCal is Palm Canyon. I first went with the ex on a planning trip for a GSA field trip he was organizing for the Salton Trough and Sierra al Mayor in Baja, way back when. I loved it on that trip, and still do.

In 2005, I had some field work in Coachella Valley, on the Whitewater River. We all had some extra time, so we decided to hike up to Palm Canyon at the end of our work day. It's on the Agua Caliente Reservation, so you have to pay to enter the park, but it's well worth it. The first photo shows the view from the upper parking area northeast towards Palm Springs with the Little San Berdoos in the way background (the thin grey line on the horizon).

This is a waterfall in a side canyon to the main canyon. The stream has carved smooth notches into the boulders making up the canyon walls and floor. As we hiked out from this side canyon, we all felt an earthquake, one of about three that day, if I recollect correctly.
Though it was a pretty warm day out (as summer days in Coachella usually are), it was cool and misty in the side canyon.
The hike up the canyon is spectacular, both geologically and botanically. The palm oases were well-managed as a food, water, clothing, and shelter source for the Coachella Valley tribes (as well as AZ tribes with access to oases). Plant, bird, herp, and insect species pretty much abound. There are a few good references, but Jim Cornett from the Living Desert Museum in Palm Desert, has published quite extensively on the natural history of the Lower Coloradan desert.

Hiking down to the side canyon, just before the earthquake. Palm Canyon is also home to a primary fault in the Santa Rosa Mylonite zone, the Palm Canyon Fault. For about a couple miles or so, as you drive south from Palm Springs to Palm Desert, you can see the deformation of the granodiorite wane as you get closer to the edge of the deformation zone. The fault trends southwest-northeast, and the deformation (if I recollect correctly and please correct me if I misremember) is evident primarily on the southeast side or upper plate.

This side canyon is in the lower plate, and has relatively undeformed geology, as compared to the other side of the canyon.

This speaks for itself. This photo was taken on the main trail, fairly close to the fault. The granodiorites are well-sheared.

Yours truly, gesticulating madly at the surface expression of the Palm Canyon fault. It's pretty beat up, here.