Photo of A highly visible section of the San Andreas Fault, in southern California

Weekly Gem #55 Faulty Geology

Published 1/16/2016

Location: This 'hidden gem' is at the intersection of the San Andreas Fault and Panorama Road in southern California (it is inside the Carrizo Plain National Monument, west of Bakersfield. See Clue Me! map). This gem is in the middle of (nowhere) a large grassland, so you can see a long stretch of the San Andreas Fault.

Of course, the first thing everyone notices is that this is a "right lateral transform fault." At the risk of stating the obvious, this means that the coastal side is moving north relative to the continental side, but also in a fairly level path ... not a lot of dipping or rising, but both sides remaining more or less at the same level. This means you can match up rocks across the fault. For example, at the location of this gem, cross to the east side of the fault.  Find some very striking rock feature, an obvious strip of quartz or something readily identifiable that has 'broken' at the fault. Now, go north and see if you can find the matching piece of rock on the west side ... you might want to drive though, because the west side rock is nearly to San Francisco by now.  While you might not find your quartz, there are large geologic features that have been split by the fault ... for example there's a volcano ... the east half is in LA, and the west half is a couple hundred miles north by northwest. 

Within the Carrizo Plain, this phenomenon is easier to see at certain stream beds, which come down the hills from the east, hit the fault and turn north, then turn back westerly a few hundred feet later.


Here's the hidden gem entry from our Clue Me! map.


Faulty geology


A highly visible section of the San Andreas Fault

Why It's Interesting

This is a geologically interesting spot, where you can see the San Andreas fault very clearly. Two tectonic plates are sliding past each other at about 2.5 inches per year. The Pacific plate, on the west side, is moving NW in relating to the North America plate to the east. This is one of the only regions in the world where the fault lines between tectonic plates are on land.