We visit Palm Springs / Palm Desert (Marriott's Shadow Ridge, where we own) almost once a year. We have ridden a bike ride that gives a great appreciation for the desert, and the San Andreas Fault, which runs along the eastern side of the Coachella Valley (I-10 parallels the fault, though not next to it). Along the ride, you can see geology up close as you see how the rocks are pushed up at strong angles.
Big Wheel Bike Tours (http://www.bwbtours.com/) picks you up at your hotel, provides bikes, and returns you ~ four hours later. You go down ~1,200 feet in elevation during the ride, which is leisurely, and with breaks. The "Earthquake Canyon" bike ride is through Box Canyon.