Just north of Barstow, California, in the heart of the Mojave Desert, lies an eroded and slightly folded basin of multicolored sedimentary rocks that contrasts strikingly with its nearly featureless surroundings. The basin includes bluffs and ledges, and even more intricate erosional landforms that are defined by layers ranging in color from gray to red to pale green to buff.
Rainbow Basin is protected as a scenic area and no off-road motorized activity is allowed. In particular, the drainages are off-limits to ATVs and dirt bikes, which both preserves their limited vegetation and makes them attractive for hiking. Many narrow down to become slot canyons upstream, and even end in dry falls that turn into waterfalls during the rare heavy cloudbursts.
Because of their contrast, it is easy to trace the different strata around the basin, and generations of students have also learned beginning field geology in this area.
Know Before You Go
Go north on Irwin Road (NOT "Fort" Irwin Road, which is a different road) 6.0 miles from its intersection with North 1st Ave. in downtown Barstow to Fossil Bed Road. Turn left on Fossil Bed Road and proceed 2.9 miles to a turnoff on the right, which is the Rainbow Basin (or Fossil Canyon) Loop Road. This intersection should be signed.
It is now 0.4 miles to a turnoff on the right to Owl Canyon Campground, a primitive campground having vault toilets, limited water (which is trucked in), and no hookups. Bringing your own water is strongly advised. The campground is about 1.5 miles up this road.
The loop road is one-way past the campground turnoff. After looping through the basin for about 3.7 miles it intersects Fossil Bed Road about 0.7 miles west of the original turnoff. In dry weather, it should be passable to ordinary passenger cars.
Again, motor vehicles must stay on designated routes, and in addition, only street-legal vehicles are allowed. There is also no fossil collecting without a permit.