Rainbow Basin has a diverse landscape of hills, canyons and washes. It is accessible to the public approximately 8-miles north of Barstow, California, via Irwin Road to an unpaved easy, one-way 4.6-miles loop through the colorful basin.
The basin is notable for the fantastical and beautiful shapes of its rock formations: its fossil beds, which have provided scientists with valuable information about life during the middle Miocene epoch, between 12 and 16 million years ago; and to the northeast the Calico Early Man Site.
Rainbow Basin has been designated a National Natural Landmark and is a mixture of private and public land but it is managed by the Bureau of Land Management (BLM).
According to ‘Geology Underfoot in Southern California’, by Sharp and Glazner, Rainbow Basin is a spectacular area of 18-13 million year-old volcaniclastic sediments and ash layers overlain by recent unconsolidated sediments.
The volcaniclastic sediments have weathered to a huge variety of bright colors hence the name of the place. Now try saying volcaniclastic 3 times fast!
Rainbow Basin is beautiful any time of the year. Summer is often in the triple digits. The road is dirt and gravel but well-maintained. Accessible by most higher clearance cars and 4-wheel drive vehicles.
As with all road trips, make sure you have enough gas, water and food to make the ride enjoyable and safe.
Different times of the day accents different shadows and colors.
A major feature in Rainbow Basin is the unique formation called the Barstow Syncline, a “U” shaped fold in the rocks. In structural geology, a syncline is a downward-curving fold, with layers that dip toward the center of the structure.
The syncline is like a wrinkle in a rug. On the north side of the basin, all the rocks dip south, and on the south side of the basin, the rocks dip north.
Park your vehicle to the side of the road and go for a walkabout. Hiking Owl Canyon offers many discoveries, such as lava tubes and dry water falls.
Owl Canyon Campground is designated as an Area of Critical Environmental Concern due to landscape features and paleontological resources in the area.
There are no dumping facilities, or potable water on site. Fires are not allowed outside the designated campground. The loop is not recommended for motor homes, big rigs, or vehicles towing trailers.
Keep an eye on the weather, as the road and washes may become flooded during cloudbursts. If it’s recently rained, the road may be washed out in places. Desert roads can become slick as goose snot after a downpour. There is no cellphone service in the area.
The city of Barstow can be reached via Interstate-40, Interstate-15, Highway 247, or Route 66 (Old National Trails Highway).
From Main Street, in Barstow, travel north on First Avenue and turn left on Irwin Road. Proceed out of town until you see the sign for Rainbow Basin.
Turn left on Fossil Bed Road and follow signs either to Owl Canyon Campground or the Fossil Canyon Loop Road. The dirt loop road returns to Fossil Bed Road just west of this entrance.