South by West of Center: Monitor Valley Salt Flat or Dry Lake

We were driving up Monitor Valley towards Potts Ranch Hot Springs (yes, up is north in this case), when we both spotted a strange whiteness on some hills located just north of the playa in the center of the valley. I had noticed this phenomenon at this site once before, but had attributed the light coloring of the hills to white beds of sediment, poorly welded ash-flow tuff, or air-fall tuff in the Tertiary volcanic section, and hence, had just driven on. This time, it looked as though dust or salt had blown northward off the playa.

We decided to check it out. We turned right on the decent side road that crosses the valley, drove to the closest whitish hill, and stopped amidst some white to very pale green bushes. The unnamed playa is located about 23 to 24 miles south by west of The Geographic Center of Nevada. (MSRMaps location).
I'm assuming the bushes are fourwing saltbush, or Atriplex canescens, in its wintry, somewhat non-leafy form.
Yes, they are covered by a thin coating of a white salt, an encrustation that flaked off easily into my hands.
To investigate this phenomenon further, we walked out onto the playa, a soft playa characterized by crusts. The photo (above) shows how the bushes gradually lose their salt crust going away from us along the northeastern playa edge, and shows part of the Monitor Range in the distance.

The crusty, soft surface is partially covered by windblown detritus.

The wind direction while we were out there was from south to north (right to left in the photo), which explains the salt coating on the bushes, unless the salt coating developed when winds from the south were blowing across a playa covered or partially covered with water.
When the playa surface is examined closely, circular features can be seen in the crusts. These circular patches will come up as blocks if prodded, and are (I hypothesize) most likely some form of biotic or cryptobiotic crust.
Looking back to the north toward my truck: the salt on the bushes is somewhat variable in distribution, apparently thinning away from playa's edge.
Now I turn and look down the five-mile length of the Monitor Valley playa. Monitor Valley continues another 25 miles beyond the south end of the playa, ending in the faint turquoise mountains in the far distance: the southern part of the Monitor Range. There is water on the playa in the far distance on the left (hard to see in this shot), and we have spotted a couple unknowns on the ground in the middle distance.

We decide to walk across the soft, crusty surface to see what's out there.

It's an old, salt-encrusted wooden post, fallen from its previously upright position, along with some other stuff of unknown origin or purpose. Picking the post off the playa floor pulls up the salt crust, revealing white to pinkish crystals on the bottom of the crust. I didn't try a taste test.

Salt crusts (possibly partly biogenic) out near the wooden post.

Salt encrusted wood, looking for all the world like driftwood.

And now, for the cold walk back to the truck.

De Re Metallica

A—Twig. B—Trench.

Prospecting by twig and trench, as shown in one of my favorite books, De Re Metallica by Agricola. Source of image: Wikimedia.

Therefore a miner, since we think he ought to be a good and serious man, should not make use of an enchanted twig, because if he is prudent and skilled in the natural signs, he understands that a forked stick is of no use to him, for as I have said before, there are the natural indications of the veins which he can see for himself without the help of twigs. So if Nature or chance should indicate a locality suitable for mining, the miner should dig his trenches there; if no vein appears he must dig numerous trenches until he discovers an outcrop of a vein.

For a miner must have the greatest skill in his work, that he may know first of all what mountain or hill, what valley or plain, can be prospected most profitably, or what he should leave alone; moreover, he must understand the veins, stringers[1] and seams in the rocks[2]. Then he must be thoroughly familiar with the many and varied species of earths, juices, gems, stones, marbles, rocks, metals, and compounds. He must also have a complete knowledge of the method of making all underground works. Lastly, there are the various systems of assaying substances and of preparing them for smelting; and here again there are many altogether diverse methods.

[1] Fibrae—"fibres." See Note 6, p. 70.

[2] Commissurae saxorum—"rock joints," "seams," or "cracks." Agricola and all of the old authors laid a wholly unwarranted geologic value on these phenomena. See description and footnotes, Book III., pages 43 and 72.

Quotes are from De Re Metallica at Project Gutenburg,
Book II and Book I, respectively.

Read De Re Metallica at Project Gutenburg.
Read De Re Metallica at Internet Archive.

This post has been submitted to Accretionary Wedge #43 at In the Company of Plants and Rocks.

UPDATE: Geologic Illustrations Galore -- Accretionary Wedge #43 is now up!

South of Center: Potts Ranch Hot Springs

I'm not exactly sure where to start on the way to ending up at Northumberland Pass and the Northumberland caldera, so we'll start at The Geographic Center of Nevada and work more or less backwards in time. MOH and I had taken two trips to Austin, with major and minor side trips into the caldera and to Spencer Hot Springs on both trips.

On the second trip, we ended our second day at the sign for the geographic center. We started in Austin, drove over Austin and Bob Scott Summits on snowy roads, went down old Highway 8A (now NV S.R. 376) in a dust storm, crossed Big Smoky Valley on the graveled Northumberland Mine road, and meandered into the central and south part of Northumberland caldera on good and cruddy dirt roads. We then proceeded back to the Northumberland Mine road, went up Northumberland Canyon, crossed Northumberland Pass, and headed down East Northumberland Canyon into Monitor Valley. It had been a long day. My photos began at 9:40 a.m. in Austin and ended at 4:35 p.m at the north end of Monitor Valley after a road trip of more than a 100 miles, not counting our side trip into the caldera.

Our first stop on this backward trek is Potts Ranch and Potts Ranch Hot Springs, located about 16 to 17 miles nearly due south of center.

Potts Ranch ranch house.

We drove into Potts Ranch from the south, following tentative directions heard the night before at the International bar in Austin, which assumed that we'd be coming in from the north via the Pete's Summit road. Fortunately, I also had a set of printed out topo maps, although the ones I had didn't name Potts Ranch or give a name to the nearby hot springs. Potts Ranch is shown on the 7.5' topo map of the area.

A stone building just behind the ranch house.

Our verbal directions mentioned this stone building, so we knew we were on the right track.
It was a frigid afternoon, and ice covered the flat north of the dirt road approaching the ranch house, where the creek flowing north from the hot springs must have overrun its banks. Other ranch ruins can be seen in the distance on the right, and cows are grazing in the far field on the left. Sastrugi shapes in the snow suggest a dominant wind direction from the north whenever the snow was blowing, though the wind was blowing from the south while we were there.
Here we're looking south at the frozen creek and at two reddish brown hills of Tertiary ash-flow tuff. To get to the hot springs, we'll drive just north and then east of the closest hill, then we'll follow a rutted dirt road all the way to the south end of the far hill.
The tub was empty when we arrived, so we moved the three black plastic pipes onto the metal rail so the filling process could begin. We also plugged the drain hole.
I think the idea is that you can fill the tank with one, two, or three of the pipes depending on what temperature you prefer. We wanted the water to be as hot as possible.
While waiting for the tank to fill, we walked around and looked at the marshy, grassy wetlands, which is drained by several steaming hot creeks. The Toquima Range is in the background.
A second hot creek in the foreground and a distant hot creek in the background give off steam, again with the Toquima Range in the background.

Another view of the same hot creeks.

Here I've walked around to a small warm or hot pond that may be fed by the same spring feeding the bathing tub. The Monitor Range, on the east side of Monitor Valley, is in the background.

Frozen grasses on pond's edge.

About this time, with the tub almost half full, we realized that neither one of us wanted to face the chilling wind or experience the icicles that would hang off our hair and face after bathing in the not-quite-hot-enough water (reported at around 100°F). We pulled the three black plastic pipes off the metal rail, unplugged the drain hole, and got in the truck.
We stopped at the spring source of the hot creek that supplies water to the soaking tub, before driving out and back to the main road north.

Green plants growing along (and in) the hot creek downstream from its source spring; ice on grass or sedge.

Green to light bluish plants or algae, waving or rippling in the flowing water.

Mirage Links

This post at Earth Science Picture of the Day (EPOD) got me started.

Mirage - Wikipedia

An Introduction to Mirages - Andrew Young at SDSU: links, explanations, and many more pages

Mirages & Refraction - Atmospheric Optics

Superior Mirage - NSIDC

Inferior Mirage - Polar Image

Highway Mirage - EPOD

Green Flash - Atmospheric Optics: also see the subsections

An Introduction to Green Flashes - Andrew Young at SDSU: links, explanations, and many more pages

Green Flashes at a Glance - Andrew Young at SDSU: a few basics

Green-flash Fallacies and Misconceptions - Andrew Young at SDSU

Pictures of Green Flashes - Andrew Young at SDSU: links to pictures and much more

Green Flash Simulations - Andrew Young at SDSU: links to the simulations are near the bottom of the page under What's available

Mirage here at LFD

Things You Find in the Field: Skull and Bones

MOH and I found these scattered bones on the flood plain of Slough Creek near Highway 50 at Devils Gate when coming back from our breccia hike. We thought it might be a sheep (or more than one sheep) because of the bits of wool (or light colored fur?) that were scattered all around.

I'm not terribly good at identifying bones, but found these comparison skulls: cow, sheep, mule deer, and another mule deer, enlarged from this page. Still can't tell! Any ideas?