Rainbow Basin Natural Landmark is approximately 10 miles north of Barstow (144 miles from L.A.). From Main St. Barstow take Ft. Irwin Road. The turnoff is on the left about 5 miles north of Barstow. It is signposted, but keep your eyes open. A one way loop road takes you though a good portion of the area and is well worth it even if you don't have time to walk around. There is a campground nearby in Owl Canyon with water and toilets.
- What to see
Well worth a side trip if you are passing through Barstow- getting out of
your air conditioned car is optional. The one way loop road winds through
the area passing both through and by some impressive rock formations. Colorful
layers of rock lie at fantastic angles that have been cut away by the action
of water. The technical term for what you are driving through is a syncline,
which is basically a V fold in the rocks.
The area of canyons at the carpark near the center of the loop is well worth
a stroll around. As you walk through them into the Mud Hills you may discover
one of the caverns that have been cut into the walls. A walk through the
main area of the canyons can probably be done in 30-45 minutes, but there
are plenty of diversions if you would like to stay longer. If you enjoy
exploring this area try Owl Canyon which also has caverns and is just north
of the nearby campground.
This area has the distinction of being a National Natural Landmark. One
of the reasons for this designation is unlikely to be noticed though; it's
famous for it's fossils. These were plentiful in the early part of this
century, but it's unlikely you will find any these days except possibly
after heavy rains (they cannot be taken from the area). A wide range of
fossils have been found here, ranging from sabertoothed tigers and rhinoceros,
to ducks and plants. They proved important enough that paleontologists have
named a period of time after the area (Barstovian, 12-16 million years ago).
At that time the region contained a shallow lake.
The rock formations that can be seen at Rainbow Basin have been built up
layer by layer, both by sedimentation when the area was covered by water
and by volcanic deposits. The layers have been buckled by movement of the
Calico fault which runs through the area. In Rainbow Basin the fault bends
rather than passing straight through causing the land to buckle and fold.
For those who want to learn more about the geology of the area "Geology
Underfoot in Southern California" by R.P. Sharp and A.F. Glazner is highly
recommended and should be available from your local library.