Thursday, January 5, 2017

Notes from the North: Snow and Ice

It's been icy cold in the far northlands, with temperatures hovering not too far above zero for several days. The snow isn't really all that deep, only 8 inches in the back yard, but it's covering everything and hanging fairly heavy on the trees.
Snow on black spruce.
Looking upward, we can see ice crystals frozen on to the needles.
It was about 3°F when I was out taking these photos.
Brr!
Ice crystals on the twigs of a deciduous tree.
Ice is a mineral of the hexagonal crystal system. The crystals in this photo consist mostly of needles and plates, probably a combination of of soft rime ice and hoarfrost.

I'm hoping for some sun today so I can take more photos of the ice-laden trees.

Tuesday, December 13, 2016

Twelve Months of LFD (2016)

I'm doing the year-end meme wherein I compile the first sentence of the first post of every month. Meme rules are as follows, as per DrugMonkey:
Post the link and first sentence from the first blog entry for each month of the past year.
I also add the first photo from the same first post. Previous takes on this Twelve Month meme at LFD were posted for 2008, 2009, 20102012, 2014, and 2015.

Aaand...here's the year 2016 for LFD:

January:
I've gathered up a collection of rocks to see which ones will float and which ones will sink.

February:

After checking out the southern route to Mineral Ridge while on my 1976 thesis quest, I headed north out of Silver Peak on then Highway 47 (now S.R. 265), carefully measuring the miles to the left-hand turnoff.

March:
With Mineral Ridge in my rear-view mirror, I stopped briefly at the basalt cinder cone, The Crater, which is located right on the side of the road just a few miles north of Silver Peak.

April:
From the vantage point of the end of the last post, a little southwest of Luning, Nevada, I turned around and pointed my camera northeast across Soda Spring Valley ... and paused to think back to the late 1980s, when we in the Western District of Former Mining Company had finally taken over exploration of the Walker Lane, which until then had been a mostly unexplored part of the Nevada District.

May:
I'm not sure how I got started on checking different words and concepts on Google Books Ngram Viewer yesterday, although my "History" tab suggests to me that it might have been related to some reading I was doing on science fiction.


June:
I collected this hand sample from the Original Bullfrog mine, Nye County, Nevada, sometime back in the mid to late 1980s when doing recon in the area, then cut and polished it—probably with a company saw and grinding wheel.

July:
We're now about two thirds of the way up the hill toward Red Pass on the Titus Canyon road, a one-way road that runs approximately east to west from Nevada into California, starting not far south of the ghost town of Rhyolite.

August:
There I was, preparing a few photos for posting in the ongoing Death Valley Trip – Titus Canyon series, doing my usual thing of marking up photos in MS Paint (I'm too cheap to buy any real photo programs), when I figured that I must have something around the house that might work better than either dragging the cursor across the screen with my trackpad or dragging my finger across the computer's touch screen.

September:
Now we'll leave the parking area near the Leadfield sign and, as I promised last time, we’ll walk out to what I’ve been referring to as the “far west cabin," although maybe that should really be "far northwest cabin."

October:
At the end of our last post—the one about the non-fold—we came into Titus Canyon proper and were looking at this view, down the canyon and to the west

November:
Just a bit of stibnite for your #MineralMonday.

December:
When I drove to the area on the south side of the Whipple Mountains where I ended up camping amidst downpours and nearby lightning, I thought I'd grab a few photos of the Colorado River Aqueduct, which passes through just north of CA Highway 62 on its way to the greater L.A. area, but an RVer was camped just beyond the aqueduct overpass, so I blew it off until I left.

Tuesday, December 6, 2016

More From the Road: Tilted Every Which Way?

I stopped while driving through the Virgin River Gorge in northwest Arizona to take this picture of some of the dipping sed rocks that are common through the greater Colorado Plateau area. (This area, lying barely within the Basin-and-Range province, is just outside the Colorado Plateau proper, but the rocks here are correlative to those throughout the plateau region, and they have been subjected to some of the same tectonic forces.)
It looks like the sedimentary layers are dipping every which way!
This second photo zooms in just a bit, focusing on the far hill, which shows a slight bend in some of the layers.
I've drawn in a few of the beds, as before, and point out a dip slope formed on the top of the reddish layer.
This Google Earth image of the area shows the photo location in purple.
I decided to see whether the beds were really dipping every which way. I used beds I could identify in Google Earth, picked out two points along the beds that were at the same elevations, and drew strike and dip symbols from these two points (method described here). The dip slope labeled above is the small lens-shaped hill beneath the central strike-dip symbol. It became apparent from looking at Google Earth that the primary reason the dips in the photos look cattywampus is because the rocks in the foreground are dipping toward the photographer (to the WNW), and most of the other beds are dipping in a more northerly direction (NW, N, or NE).
The same Google Earth image with some hypothetical strike-dip symbols.
So, how did I do on the strikes and dips? And is there anything else going on in the area? Well, okay (ish) and yes.
Map I-2165 (Bohannon et al, 1991) courtesy USGS, overlain on Google Earth.
The Cedar Wash high-angle reverse fault cuts right through the area, separating the strata dipping toward the west (the foreground strata in our photos) from strata dipping in a northerly direction. You can see, by clicking on the several images and going back and forth between them, that I did well on the strikes on the west and east, and not so well (in general) on the strikes in the center. Either that, or the strikes of beds in the center varies more than shown on the map (I'm pretty sure I did pretty well on the labeled dip slope, but I will never climb that hill to check it out!)

Read a little about the Cedar Wash fault and the general geology of the region here.

Thursday, December 1, 2016

More From the Road: The Colorado River Aqueduct

When I drove to the area on the south side of the Whipple Mountains where I ended up camping amidst downpours and nearby lightning, I thought I'd grab a few photos of the Colorado River Aqueduct, which passes through just north of CA Highway 62 on its way to the greater L.A. area, but an RVer was camped just beyond the aqueduct overpass, so I blew it off until I left. (I'm not terribly social while in the field, especially when traveling along.) On my way in, I took one shot showing the signage and the overpass (first photo). In the Whipples (and elsewhere), the aqueduct goes underground in several places, usually to allow passage of large dry washes. It's at these points that dirt roads can cross. The sign says, "Private Right of Way. Any Person Entering Thereon Does So at His Own Risk. Permission to Pass Revocable at Any Time. The Metropolitan Water District of Southern California." It is probably referring to the road paralleling the aqueduct, rather than the road crossing it, but who knows.

I stopped to take a few more photos on the way out during the early morning of the next day (after having coffee, of course!). These photos can be used to help illustrate a few stories I have about doing recon and exploration in the Whipple Mountains area—stories that date back to 1981, resume in 1983, and continue off and on after that through the late 1980s. (That's really why I went out of my way to drive into the area in the first place.)
The entire aqueduct, where above ground, is surrounded by a fairly hefty chain-link fence and more "No Trespassing" type signage in English and Spanish.
In this second view (above), Savahia Peak and its detachment-tilted Tertiary volcanic rocks, which we saw earlier, is sticking up a little.
View of the aqueduct looking through the chain-link fence.
While working in the area during a misconceived June recon program (June: ugh and yikes!), my field partner and I fantasized about cooling off in the water by tying ourselves off to the fence with ropes. We didn't think we'd want to be sucked downstream into the next underground section of the aqueduct, even though that section is a relatively short one: only 204 feet (61 m). But the rope idea, that might work!

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.