Carrizo Plain, California

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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The best way to see the Carrizo Plain is, well, by plane. It has the most spectacular expression of the San Andreas Fault but the famous stream offsets are best seen from the air. The best road through the area doesn't parallel the fault closely, and isn't high enough to offer really good vantage points. But if you want reassurance that California still has empty places, this is it.

In the map above the Carrizo Plain is yellow, the Central Valley light green, other valleys brown. Faults are red. There are numerous faults in the Coast Ranges parallel to the San Andreas that in the past (and possibly even now) took up some of the transform motion between the Pacific and North American Plate, but only faults of the San Andreas Fault system and the Garlock Fault System (extreme lower right) are shown.

Below are strip maps of the Carrizo Plain. At left is a hypsometric map, at right a shaded relief map. Note that the maps are tilted. Northwest is at the top, southeast at the bottom. Elkhorn Road, the best overall road along the fault zone, is highlighted in light blue. The photos in the center roughly match the corresponding positions on the map. In detail, the San Andreas Fault consists of numerous strands.

 

There are two ways to get to the Carrizo Plain, neither of them easy. The short way is to take State Route 58 west from Bakersfield and then turn south on Elkhorn Road. Most of the best fault features are in the north.

The long way is to take California State 166 a few miles southwest of Maricopa, then take the first paved road west. It doesn't stay paved long. The gravel road is passable by car. There are myriad other tracks in the area, best driven with high clearance vehicles.

Left: It's not clear whether that furrow in the hill is a fault trace or an eroded artificial  feature.
Coming into the Carrizo Plain. Most maps create the impression that the plain is separated from the Central Valley by a low range of hills. It is, in fact, a fairly impressive mountain range. Also the Carrizo Plain is about 500 meters higher than the Central Valley.
The main strand of the San Andreas is on the far side of the ridge but a low scarp is visible at the base of the ridge.
Looking south. There's a little snow on the highest peaks.
At the southern end, the range east of the plain is mostly Miocene sedimentary rocks. Eocene and Cretaceous rocks crop out in the core of the range to the north.
 
Looking west. A fault valley separates the two ridges.
Looking west.
Looking south
Looking west.
Looking north
Looking west.
Looking east.
Looking west
Looking west
Left and below: in the northern half of the Plain, a low pressure ridge marks the main trace of the fault.
Soda Lake, a playa, occupies the lowest part of the basin.
A small horst close to the road.
It's not easy to spot stream offsets from the ground.
Soda Lake, a playa, is in the distance.
A couple of miles south of Route 58, there's a pullout and placard explaining the fault scarp and pointing out an offset stream.

Below: the fault scarp

Left: The stream crosses the fault at far right, in the notch with small trees. It flows along the scarp and then downhill. The offset gully is visible at far left.
Left: The photo above with the fault in red and stream in blue. Offset sense shown in white.

Below: closeups of the offset gully and the stream crossing the scarp.

Wide angle view of the scene.
Curt Gentry's novel The Last Days of the Late Great State of California lodged the idea of California falling into the sea in the public consciousness. Somebody wants to be prepared.
Looking west over the Carrizo Plain from Route 58. The low scarp beyond the telephone lines is the fault.
Route 58 clings to the high part of the mountains for quite a while before dropping into the valley. It can get you above the perpetual murk around Bakersfield to offer views of the snow-capped Sierra Nevada.
 

References

Fault locations are from:

Dibblee, T.W., Graham, S.E., Mahony, T.M., Blissenbach, J.L., Mariant, J.J., and Wentworth, C.M., 1999, Regional geologic map of San Andreas and related faults in Carrizo Plain, Temblor, Caliente and La Panza Ranges and vicinity, California: a digital database: U.S. Geological Survey, Open-File Report OF-99-14, scale 1:125000.


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Created 15 January 2007, Last Update 01 July 2012

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