Monday, November 28, 2016

The Left-Lateral Strike-Slip Garlock Fault Near Highway 395

While out on the last road trip, I started taking pictures from places where roads crossed the Great Basin Divide. Unfortunately, I soon gave that up because freeways, which I traveled not exclusively but considerably, are lousy places from which to take pictures. But thinking about divides also made me think about the Garlock Fault, and how I'd be crossing it on 395 heading south into the Mojave. Here I've pulled over as I'm about to cross the fault.
I've drawn the Garlock fault with a thick blue line, and a secondary strand (air-photo linear) with a thinner blue line.
Besides the two fault strands, you can see the towns of Randsburg and Johannesburg, which were founded in 1896. The Yellow Aster open-pit gold mine was operated by Glamis Gold from about 1987 to 1997.

The haze was thick and the day overcast, and it looked like the photos I was taking would be fairly lousy, but MS Photos was surprisingly able to revive the dark, lackluster originals (I usually don't rely on the Photos app, but in this case it worked better than my other free programs).

After crossing the fault on 395, I took the road toward Goler Heights and Garlock. (Goler Gulch in the El Paso Mountains at Goler Heights is unrelated to Goler Wash in the Panamint Range at the edge of Death Valley National Park.)
Looking west along the southern range front of the El Paso Mountains toward Goler Heights.
The Garlock Fault is mostly behind low hills in this shot, and it runs to the right of us about three quarters of a mile to the north.
I've drawn in two (or three) apparent strands (or air-photo linears―my interpretation may not be precise in all cases) in dashed blue lines; where thin, the fault is behind hills or out of view.
We're now back near the junction of the Goler Road with Highway 395, looking to the northeast.
I took this photo thinking that we might be seeing part of the Garlock Fault, when in fact what we're seeing is a couple of fault strands parallel to the Garlock (air-photo linears).
The Garlock Fault proper is out of view beyond the low hills.
A little more than a mile to the NNE from the place I took that last photo (above), there's a great example of a shutter ridge and offset drainages.
Google Earth image with a blue line I added using the "Path" function.
The same image with more scribbles.
This marked up Google Earth image shows a small portion of the left-lateral Garlock Fault (long blue line). The fault line is basically the same as shown here (Roder, 2012). If you blur yours eyes a little (and even if you don't), you'll probably see several lines or linears that are running parallel to the main fault trace. I drew a few of these in with thinner dark blue lines. I can easily spot a few more.

The fault has offset two drainages in a left-lateral sense; that is, the south side of the fault, moving to the northeast (right) has brought in a ridge that has blocked the dry wash in the center of the image, forcing it to flow to the northeast to get around the ridge. That ridge is labeled "shutter ridge," which is the term for a ridge that blocks a drainage in this fashion along any strike-slip fault, whether it's right lateral, like the San Andreas, or left lateral like the Garlock. A second drainage way off in the upper right corner of the image has been blocked and offset in the same fashion. That drainage appears to have two shutter ridges, one that is north of the main trace of the fault, and another that looks like it's south of the main trace (at least the way the main trace has been drawn; we can see by drawing in just a few air-photo linears that there may be a few complications, and faults often meander around a bit).

I got back onto Highway 395 and continued south toward my destination, figuring that I could get a photo looking back toward the Garlock from somewhere up near the turn-off to Randsburg. I finally found a pullout on the east side of the highway; it offered me a four-wheeling opportunity to drive a very narrow, rocky road to the top of a small hill. The photos I took from there looked really lackluster, so I didn't spend a lot of time trying to get a really good panorama. Consequently, the two photos I've stitched together below do meet up on the horizon, but they are way off in the foreground, primarily because I ended up moving to keep the dirt road I was on out of the picture. We can, nevertheless see where the Garlock and a couple parallel strands or linears are located.
Stitched photo. The center of the photo is looking just west of north.
The same photo with a few labels.
And that's basically it for the Garlock Fault, but there's a location near Goler Heights that might be a good spot to look around the fault, and there are probably some good locations near Garlock.
Looking northeast from Goler Heights along the Garlock Fault.
UPDATE: Be sure to view Ron Schott's GigaPan of this portion of the Garlock Fault.

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