Tuesday, November 24, 2015

Views from Glass Mountain

After we finally arrived at our chosen overlook part way up Glass Mountain, we milled about a bit (it was a geology field trip, after all), and then we gathered 'round a map that one of our tour leaders, Julie Donnelly-Nolan, had placed on the ground.

Above, my rock hammer is in front of blocks of relatively light-colored, vesiculated, rhyolite obsidian (AKA pumice, but in this case it's pumiceous flow-rock, not tephra).

Before I get to a few views of the area, I'll go into the geology just a little:
Julie Donnelly-Nolan points to her map of the Glass Mountain dacite-rhyolite flow, Siskiyou County, CA.
The map, not included as part of our field guide packet (Coyner, 2015), was created by Julie, a geologist for the USGS. She's been working in the area for many years. The map is similar to a map by Eichelberger (1981), which he published in an article about magma mixing at Glass Mountain, an article that is part of a larger field guide to several volcanic areas in Idaho, Oregon, and northern California (Johnston and Donnelly-Nolan, 1981). The road log for the Glass Mountain part of our GSN trip was taken in large part from the Medicine Lake Highland road log section of that larger field guide (Donnelly-Nolan et al., 1981). If you check out the guidebook, be sure to read Wes Hildreth's tribute to David A. Johnston, who died at Mt. St. Helens in 1980. The 1981 field guide was published after his death.

As you can see below in a rotated version of the map, the Glass Mountain dacite-rhyolite flow "consists of three dacitic eastern lobes which grade westward to rhyolite and are overlain by rhyolite lobes" (Donnelly-Nolan et al., 1981, and in Coyner, 2015). Well, maybe not all of that is obvious at first glance, but read on.
Map showing the silica content of different parts of the Glass Mountain dacite-rhyolite flow (Donnelly-Nolan, unpublished). North is up.
During the rest of this post, I'll be referring to the dacite flow lobe (purple, in the northeast), the rhyodacite flow lobe (red with a central ribbon of orange, in the southeast), and the south flow lobe (mixed orange, red, and purple, in the south to southeast). I'll also mention the rhyolite flow lobe (the central and northern orange area, including a well-definable flow and central dome area with margins that overlap the slightly older dacite and rhyodacite lobes), and the mixed area centered between the dacite and rhyodacite lobes.

On the map, the highest silica parts of the flow, the rhyolite, are in orange; the parts of the flow with lowest silica content, the dacite, are in purple; the areas with silica content in between rhyolite and dacite, essentially rhyodacite, are in red. NOTE: Though by many classification schemes the silica content of rhyolite is about 68 or 69% and higher (the USGS appears to be using two different cutoffs), and the silica content of dacite ranges from about 63-68% or 69%; TAS diagrams show dacite compositions as high as 72-75% (depending on what version of TAS one happens to choose; here's one; TAS explained here and here; and a lot more about the classification of igneous rocks—including all kinds of diagrams, references, and a flow chart—can be perused here). Rhyodacite is a term generally used for rock composisitons between rhyolite and dacite (USGS, OSU), rather than a specific field in most classification systems.

The colorful map (I love color!) shows that the lithologic composition of the overall flow, which is thought to have erupted during the course of several or many days or weeks rather than over several months or years, is quite variable. The complexities of magma mixing and eruption to produce this variability are described by Eichelberger (1975, 1981). Basically, it's complicated: first, basalt intrudes a rhyolite magma chamber; then mixing creates rhyodacite and dacite, which float to the top of the chamber in his eruption scenario; eruption, triggered by the mixing, produces dacite, then rhyodacite, then rhyolite.

Below, I decided to see what kind of map I would come up with going mostly by color and topographic expression of the flows (with a lot of help from Julie's map).
Google Earth image of the Glass Mountain dacite-rhyolite flow.
Here, I've delineated the dark areas with purple lines, the light, viscous, and some banded areas with orange lines, and the in between areas with red lines.
You can see that there are several areas where the lines I've drawn could be moved around, for example some of the banded areas: do they belong properly in our red or orange category?
I've added some colorful fill to facilitate comparison to the geologic map.
Here's the rotated map again (and it's skewed).
My "map" or cartoon as drawn on the Google Earth image is comparable to the rotated geological/compositional map (yay!); but really, this was just an inconsequential exercise, one that could have easily produced a considerably different map, possibly by using as many as 5 major fields (for example, if the banded-looking areas were picked out separately, and with the upper, well-defined rhyolite flow that heads off to the northeast drawn as a separate unit). Without chemistry or an already existing geologic map, this is the sort of exercise that could be done prior to heading into the field, giving the mapper an idea what to check out, although just taking an aerial image or air-photo into the field would serve the same purpose.

Well, that was really a kind of long aside, almost like a post within a post!

Besides hanging around the map and hefting large rocks, the view from the east side of the rhyolite flow (see our location below the post) was good—not great simply because of the low-hanging clouds that hadn't lifted.
Photo looking south.
I thought I might have the actual top of Glass Mountain in this photo, way over to the right, but the dome-shaped peak was covered with clouds. Instead, we can see the steep face of the rhyolite flow where it abuts a highly mixed part of the flow: the central section between the rhyodacite and dacite flow lobes (see map above).
Photo looking nearly due east.
This view looks out across the dacite flow lobe (dark brown and mostly in shadow past the light-colored rhyolite blocks in the foreground). Timber Mountain, the circular, gently sloped mountain dead center in the distance, is shown to be underlain by the the "older basaltic andesite of Timber Mountain" on Sheet 2 of this map (Donnelly-Nolan, 2010). It has been dated at 1.820±0.042 Ma, i.e., late Pliocene.

Oh, and btw, the Glass Mountain flow erupted about 900 years ago: it has a calibrated radiocarbon age of 890 BP (Donnelly-Nolan et al., 2007).
With the blocky rocks of the dacite flow lobe in the foreground, we look northeasterly in this photo. That's probably Double Head Mountain just left of center; the north edge of Timber Mountain is on the far right.
And now, we've already started back down. I'll have a few more photos along in a while...

A Few References:
A Web Browser Flow Chart for the Classification of Igneous Rocks - a lot of info (largely from Le Bas and Streckeisen, 1999, and other related sources), and a flow chart

Tephra and Volcaniclastic Rocks - good overall classification scheme, though it doesn't reference any primary sources, and allows agglutinate to occur only in basaltic rocks

Coyner, Alan (ed.), 2015, Geological Society of Nevada 2015 fall field trip guidebook: Geology of the Far Northwestern Great Basin: Quartz Mountain gold deposit, Oregon, and Lava Beds National Monument and Glass Mountain Pumice Deposit, California [for sale here, but not yet listed]: Geological Society of Nevada, Special Publication No. 60, 71 p.

Donnelly-Nolan, J. M., 2010, Geologic map of Medicine Lake Volcano, Northern California: U.S. Geological Survey Scientific Investigations Map 2927, scale 1:50,000, Sheet 1 and Sheet 2, Pamphlet to accompany the map, 48p.

Donnelly-Nolan, J.M., Ciancanelli, E.V., Eichelberger, J.C., Fink, J.H., Heiken, Grant, 1981, Roadlog for field trip to Medicine Lake Highlandin Johnson, D., and Donnelly-Nolan, J., eds., Guides to some volcanic terranes in Washington, Idaho, Oregon, and northern California: U.S. Geological Survey Circular 838, p. 141–149.

Donnelly-Nolan, J. M., Nathenson, M., Champion, D. E., Ramsey, D. W., Lowenstern, J. B. & Ewert, J. W., 2007, Volcano hazards assessment for Medicine Lake Volcano, Northern California: U.S.Geological Survey Scientific Investigations Report, 2007-5174-A, 26 p

Eichelberger, J.C., 1975, Origin of andesite and dacite: Evidence of mixing at Glass Mountain in California and at other circum-Pacific volcanoes: Geological Society America Bulletin 86, v. 10, p 1381-1391.

Eichelberger, J.C., 1981, Mechanism of magma mixing at Glass Mountain, Medicine Lake Highland volcano, California, in Johnson, D., and Donnelly-Nolan, J., eds., Guides to some volcanic terranes in Washington, Idaho, Oregon, and northern California: U.S. Geological Survey Circular 838, p. 183-189.
jpg of lava chemistry figure (Eichelberger, 1981)

Hildreth, Wes, 1981, David Alexander Johnston, 1949-1980in Johnson, D., and Donnelly-Nolan, J., eds., Guides to some volcanic terranes in Washington, Idaho, Oregon, and northern California: U.S. Geological Survey Circular 838, p. viii-x.

Johnston, D.A., and Donnelly-Nolan, J.M., 1981, Guides to Some Volcanic Terranes in Washington, Idaho, Oregon, and Northern California [pdf version; also here in html]: U.S. Geological Survey Circular 838, 189 p.

Saturday, November 14, 2015

Update from the Lake: First Snow!

It was a cold and misty morning, with lots of smoke from wood fires drifting by (cue that wonderful scent that reminds me of fall and winter, but makes my sinuses clog up a bit), when MOH finally got me to drag myself away from the heat of our front-room oil stove. "Take some pictures," he cried, "It's the first snow of the year! And it will melt soon!" So out I went.

Well, it hasn't melted completely, four days later, though snow is gone from the patches of ground that get our low-angle, late fall sun, where the sunlight manages to slip through our neighbors' trees.
Snow on pines, firs, and cedars.
Snow on manzanita, with background of bamboo.
Closeup of snow on ponderosa pine needles.
A leaf hanging from our Blackgold® cherry, with hints of construction in the background.
Green leaves from the same cherry tree. Green!
Snow on Surefire™ pie cherry leaves.
We have a lot of fencing material here and there in our yard.
The raspberries were mostly green when the snow fell (and they still are!).
Snow on the green leaves of our Titan almond tree.
The leaves were mostly gone from the nearby Betty peach tree.
Snow on the Orus 8 gooseberry x currant plants.
Leaves of the Breda Giant and Puciu Super Mol medlars, with snow and shadows.
Snow on manzanita branches.
The manzanita from above, looking down.
Snow on the leaf of the Surefire™ pie cherry tree.
Leaf shadows.
More Surefire™ pie cherry leaves, with partly frozen drips.
Fencing wire hung hanging from the gate.
The gate, with a hint of boat in the background.
Pine needles in corn snow on concrete.
A door leaning against another door.
There is still enough snow in the shadowy parts of the yard for crunching about, and the ground is mostly still frozen, although we are having highs in the low to mid-50s. And surprisingly, at least to me, many of the leaves I photographed for this series are still on the trees and bushes, and the ones that were green are still green.

Tuesday, November 10, 2015

Links: Field Tests for Gold and Silver (or other Elements or Metals, and Sometimes Minerals)

After reviewing links on my 2009 blowpipe tests post (spurred on by this recent comment on another post), I decided to do a little more research concerning field tests for gold, silver, and other metals (primarily; some of these links are for minerals in general, though I haven't included links for the usual hardness, scratch, and other well-known tests and characteristics). The articles and books listed below may include information about blow-pipe tests (B) or info about other types of tests (O). Some include general gold, silver, and other metal or mineral prospecting information (P), many include information about other metals or elements besides gold and silver (ME), a few include info about minerals, not just elements (M), and a couple are more unknown in their coverage because they are not available in full online (U). I've listed them by year.

Merritt, W.H., 1911, Field Testing for Gold and Silver: A Practical Manual for Prospectors and Miners: Crosby Lockwood and Son, London. (B, O, P)

Osborn, H.S. and Von Bernewitz, M.W., 1920, Prospector's Field Book and Guide: Henry Cary Baird & Co., Inc., New York. (B, O, P, ME, M)

Davison, E. H., 1937. Field tests for minerals [snippet view only]. London: Chapman & Hall. (M, U)

Fansett, G.R., 1940, Field Tests for the Common Metals: Arizona Bureau of Mines Bull. 147. (B, O, P, ME)

Stevens, R. E., and Carton, M. K., 1948, Simple field test for distinguishing minerals by abrasion pH: American Mineralogist, v.33, p. 31-50. (O, M)

Roseveare, G.H., 1966, Field Tests for the Common Mineral Elements: Arizona Bureau of Mines Bull 175. [this appears to be a reprint or update of ABM Bulletin 147 linked above] (B, O, P, ME)

Franke, W.A., (no date, prob 1990s), Quick assays in mineral identification, A guide to experiments for mineral collectors and geoscientists in field work. Published online. (B, O, ME)

Pray, R.E., 2006, How to Prospect for Silver Field Tests You Can Use to Detect the Hidden Metal [abs only, or subscription required]: ICMJ's Prospecting and Mining Journal (P, U)

Basic Field Tests for Gold and Various other Metals - at Nevada Outback Gems (O, P, ME)

And of course there now is portable or handheld xrf. This is my favorite model (although I've used only two models from one manufacturer).

Thursday, November 5, 2015

Links: Nevada Highway 8A

8A sign taken by yours truly in 2015
I had a comment on an old post a while back about how there is no more Highway 8A in Nevada, and so how that makes me some kinda liar or irresponsible person or something for mentioning the old road designation in said post, so I sat down one day (probably that very day) and Googled up a bunch of links for old (and current) 8A. I've grouped the links by category, the first group being links to recent photos of 8A up in the north part of Washoe County where signs for 8A still exist (I took photos of 8A signs there in August, 2015).

"Jim Stolpa" (1993) - photo of "of NV Road 8A where Jim Stolpa..." by Acey Harper Pictures on Getty Images

"NV-8A East - Nevada State Line" - Flickr photo taken Oct 2006, by Zach

"NV-8A East - Travel At Your Own Risk" - Flickr photo taken Oct 2006, by Zach

Trip & Pics Part Two - Antelope, Wild Horses, Ruby Pipeline, Remote Nevada (2011) - mention  and pics of 8A (and the Stolpas) in a travel blog post

Steep and Rocky's Black Rock Desert Ride (2012) - mention and pic(s) of 8A on page 2 at Adventure Rider (motorcycle trips)

"Route 8A Near Vya, Nevada" - Flickr photo taken Nov 2013, by Ken Lund

"Route 8A Near Massacre Lake and Vya, Nevada" - Flickr photo taken Nov 2013, by Ken Lund

Various Links for 8A in NW Nevada:
Gateway Communities - Cedarville, via 8A, is the "western gateway to the High Rock country"

Camping, BLM California - Applegate Field Office - directions using 8A

Nevada RV Parks & Campgrounds - The Happy Camper Club - directions to Old Yella Dog Ranch via 8A

U.S. 395 route in CA - Facebook post - mentions 8A at the CA-NV stateline

Sherriff's Office investigates fatal accident in northern Washoe County - This is Reno - occurred on S.R. 8A

Lost fire update at Inciweb - NV S.R. 34 closed at S.R. 8A

News about the Lost fire at YubaNet.com - updates on NV S.R. 34 and 8A

Nevada State Route 8A at Rediff - "Former State Route 8A...signs remain...still de facto connects SR 140 with California."

Nevada lawmakers avoid tax fairness issue - mention of routes 8A and 34

Google Groups discussion about Highway 140 - mention of 8A

Various Links for 8A in Central Nevada:
District Attorney Presses for Charges in Slaying Case - archive from 1955; mention of 8A north of Carvers in Big Smoky Valley

Nevada State Journal article (1963) - "The 65 mile project will run east from Tonopah to State Route 8A junction."

Placer Gold Deposits of Nevada - USGS Bull 1356 (1973) - p. 36, 42, 62, 65: access to prospects/properties near Battle Mountain and Tonopah

A History of Smoky Valley, Nevada (1997) - see Chapter 20, about Carvers

Growing Up in Central Nevada 1941-1959 (2010) - mention of 8A in a memoir

Various Real Estate Listings on 8A:
Several near Vya (listed as Gerlach)
Near or in Battle Mountain
NOTE: There are more of these; particular listings may not remain active!

Stolpa Links mentioning 8A:
Family Rescued After Being Lost in Snow for a Week : Storm: Soldier walks for help after leaving his wife and baby in a cave. All three are in good condition. - LATimes, January 7, 1993

Family Survives Western Storms After Spending 4 Snowbound Days In Cave - Chicago Tribune, January 7, 1993

Travelers On 'Road To Nowhere' Wonder How Family Survived - Orlando Sentinel, January 10, 1993

Stranded family recounts ordeal - The Baltimore Sun, January 8, 1993

Staying Alive: Stranded Nine Days in a Snowy Nevada Wasteland, a Brave Young Family Survives on Faith, Love, Grit—and a Little Basic Training - People.com, February 8, 1993

The travails of a treacherous trip - Tahoe Daily Tribune, December 13, 2004

I should not be alive… (2006) - Blog post at Mrudulat's Blog

Inspiring True Stories Of Survival. - 2008 forum at Stormfront.org

The Stolpa family, marooned east of Vya, 1993 - 2011 forum at Wander The West

Anyone Remember this Story? - 2012 forum at Houzz

Tale of survival: The Stolpa story, Part I - Tahoe Weekly, December 25, 2013

Soldier walks for help after leaving his wife and baby in a cave - July 22, 2014 blog post on tttracy's blog

Santa Cruz Sentinel article (1993) - "It began to seem like the end of the world for the Stolpa family when no other vehicles appeared on Washoe County road 8A."

Stolpa Truck Location kmz location on 8A, Google Earth

NOTE: Many dead links (11Jun22)

Tuesday, November 3, 2015

Future Stories from the Palmetto Moutains

It's 58 miles to the next gas station at Lida Junction on S.R. 266, looking west.
In later years—in the future of the 1976 "present" of these ongoing thesis-hunt stories—I made my way back into the Palmetto-Magruder area barely a handful of times. Once, while taking a back way into Death Valley in the fall of 1986, we made some stops between Lida Junction and Lida to find some blackbrush. This notably unsuccessful endeavor was instigated by a palynologist—he preferred the pronunciation "pollenologist"—who swore he would surely be able to show us some fine examples of the cryptic bush (cryptic to us). At the time, however, most of the bushes lacked leaves (it was fall, or extra dry, or both), and while many had the dark grayish woody stems and trunks reportedly diagnostic of blackbrush, it was nigh impossible to tell one bush from another. Our palynologist couldn't positively identify a single bush! I’ve consequently never been able to ID the plant.
Corral near the junction of SRs 266 and 174, the road to Gold Point. Halogetin in the foreground, unidentified scrub beyond the fences. 

And now I'm going to deviate from my usual format to tell a story that may or may not have occurred in the Palmetto Mountains, one which I am assured by a certain geo-type, who may or may not have been present, not only did not occur, but could not possibly have occurred. Some details may or may not have been changed in this retelling. Any similarities to certain Former Mining Company trips made in the area during the mid- to late 1980s are unquestionably coincidental.

There were four of us geo-types, four geos on a 2-truck expedition into an area of old mining prospects on the south side of an east-west-trending mountain range in a relatively arid area. The sun was high in the sky, as it often is at about midday. The white Chevy pickup (this part is clear in my mind) was ahead of me, going more slowly than would have been comfortable in my company truck, which was a half-ton, 4WD Ford pickup, probably an '85. The Ford could take the deep washboard that was pervasively present through the area at higher speeds than the Chevy because of its better sway bars and other off-road accoutrements. (I know, I know; this sounds like a trite Chevy-Ford rivalry.) Consequently, I was staying a ways back, letting "the guys" go ahead. (In my truck, we were two youngish women, both geologists.)

And now we come to the controversial part of this possibly apocryphal story.

The two ahead of us—those two in that white Chevy pickup, the truck that also lacked enough gumption to go up hills in anything higher than middle gear (I won't mention here its barely SFW nickname)—took off on a hummocky-looking, powdery-textured two-track that was running straight up a steep hill. I won’t exaggerate and say this was the steepest dirt road I’d ever seen (or driven on), but something about it, besides my aversion to being right behind someone on a dirt road—ugh, the dust!—made me stay at the bottom of the hill while I watched them ascend steeply and make a sharp, overly banked turn to the right.

Up ahead in the distance, they stopped. By now we could either barely see them, or they were beyond our sight. We, who had stayed below, walked on up: it wouldn't be that far to the next prospect, and we wanted to check out the road. Oh, look! Beyond the curve the road cuts straight across the hill at a complete sidehill! Any forward or backward movement and the rear end will slide out! (The rear end is usually the part to go first; a complete roll down the side of the mountain is less common).

Disclaimer: The driver of the white truck maintains that there was no sidehill too steep for the truck at this particular locale (which I remember as being in the Palmetto Mountains), and that there was no winching uphill to a Joshua tree in progress when I showed up on foot (and no winching to any Joshua tree ever, anywhere). And the usual statement—pictures, or it didn't happen—could apply. There definitely were no pictures.

I’ll stop for now, not to leave anyone hanging or anything, and will come back to the Palmettos once more, with some roadside geology.

Related Posts:
Thesis: Finding an Area
Finding a Thesis: Battle Mountain to Austin to Gabbs
Finding a Thesis: Pole Line Road
Finding a Thesis: Pole Line to Belmont
Finding a Thesis: Klondyke District
Finding a Thesis: A Joshua Tree Aside
Finding a Thesis: Into the Palmetto Mountains
Finding a Thesis: Farther into the Palmetto Mountains
Finding a Thesis: A Bit O' Geology in the Palmetto Mountains