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.