Geology Educational Ride from Brown’s Ranch Trailhead  When, how and why did all those different rocks get into the Preserve?  How about our own earthquake fault?   This Intermediate Skills and Moderate Cardio Ride for about 3 hours over 11-12 miles will take us thru the various geological formations of the area. Get the big picture on a bike. Please, no road bikes, hybrids, folding bikes, or electric assist bikes. Please check the working order of your bike before you leave home. Helmets required.  Bring water and snacks. Restrooms at the trailhead. Please arrive 15 minutes prior to start.