Links: Field tripping in Nevada, mostly along I-80 and Highway 50

A River Runs through It [link to download], ESW 2016, E-59 NBMG: Truckee River Reno to Pyramid Lake

1915 Pleasant Valley earthquake centennial field trip guidebook: A public field trip to visit the largest earthquake in Nevada's history [link to download] E-58 NBMG: 50 miles south of Winnemucca

Fire and Ice—Geology of the Mount Rose quadrangle, Lake Tahoe, and the Carson Range [link to download pdf], ESW 2015, E-57 NBMG: Galena Creek Visitor Center to Incline Village

Carson Rocks! A Sesquicentennial Celebration of some of our Capital City's Geological High Points [link to download pdf], ESW 2014, E-56 NBMG: around Carson City

Geo- and Eco-Mapping around DRI (The Great Altered Rock Walking Tour) [link download pdf], 2014, E-55, NBMG: around DRI.

Mapping the Geology around the Desert Research Institute and Truckee Meadows Community College [pdf], ESW 2013, E-53, NBMG: around DRI.

"Tuff All Over": Exploring Faulted Volcanic Terrain in the Painted Hills, Virginia Mountains, West of Pyramid Lake [pdf], ESW 2012, E-52, NBMG: near Pyramid Lake.

"Life's a Beach": In Search of Ancient Shorelines and Volcanoes in the Grimes Point and Lahontan Mountains Area [pdf], ESW 2011, E-51, NBMG: near Fallon.

Geo-tripping in Nevada [pdf], NBMG map guide to many or most of the NBMG field trip guides in Nevada through E-50.

In search of Tufa, Tuff, and Tough Rocks [link to download pdf], ESW 2010, E-50, NBMG: stops are east of Pyramid Lake; trip guide includes Reno to Pyramid Lake, Pyramid Lake to Wadsworth, Pyramid Lake to Brady's Hot Springs, Brady's Hot Springs to Reno.

Digging Deeper into the Comstock [link to download pdf], ESW 2009, E-48, NBMG: Reno to Gold Hill.

No Child Left Inside: A field trip for Families and Rockhounds [link to download pdf], ESW 2008, E-47, NBMG: stops are near Fallon, east of Fallon, north of Fallon, and in the Truckee River Canyon along I-80; road guide runs from Reno to east of Fallon, Fallon to Trinity (junction of I-80 and 95), and Trinity to Reno.

Taking the Pulse of the Earth [link to download pdf], ESW 2007, E-46, NBMG: south of Reno (Slide Mountain, Steamboat, and Virginia Foothills; the latter two not available to public).

Rockin' Along the River [link to download pdf], ESW 2006, E-45 NMBG: Truckee River Verdi to Wadsworth

The great Highway 50 rock tour [link to download], ESW 2005, E-44 NBMG: Fallon to Middlegate

The Frenchman lake frolic [link to download], ESW 2004, E-43 NBMG: Frenchman Lake area, California, west of NV-CA border.

Get out, stay out, and stay alive [link to download], ESW 2003, E-42 NBMG: north of Reno towards Pyramid Lake.

In search of "the right tuff" but you can just "take it for granite" [link to download], ESW 2002, E-41 NBMG: north of Reno and to the west toward northern end of Red Rock Road.

Fossils and Ancient Lakes [link to download pdf], ESW 2001 field trip #2, E-40, NBMG: fossils near Nightingale.

Peavine Peak: Geology, plants, and mining history [link to download], ESW 2001 field trip #1, E-39, NBMG: Peavine.

Exploring east of the summit: A field trip guide to Steamboat Springs, Lake Tahoe, and the Comstock area [link to download pdf], ESW 2000, E-38 NBMG: Steamboat Springs, Lake Tahoe, Comstock.

Geology along America's loneliest highway [link to download pdf], ESW 2000 E-37 NBMG: Carson to Sand Mountain.

What's shakin' in the neighborhood? -- Road log [link to download pdf], ESW 1999 field trip #2, E-34 NBMG:  Reno, Mt. Rose fan/pediment, to Genoa fault scarp.

Turbulent times in the Truckee Meadows [link to download pdf], ESW 1999 field trip #1, E-33 NBMG: UNR to Verdi to Crystal Peak Mine.

Ancient lakes and volcanoes near Fallon: Field trip for families and rockhounds [link to download pdf], ESW 1998, E-28 NBMG: Fallon, Grimes Point, Soda Lake.

Link to NBMG's entire Educational series; most (all?) are available to download.

INQUA 2003 - Elko to Reno, Wadsworth Amp, Lone Mtn hwy 50, Reheis - no viewing online at Google books

Geothermal energy helps power Nevada | Elko Daily Free Press - Brady's Hot Spring, Beowawe, and "Hot Hole" in Elko

The Stories Behind I-80s Exit Sign Names - Part 1 | Backyard Traveler by Rich Moreno - various info about signs and areas, e.g., Nightingale and Brady's Hot Springs

Touring California and Nevada hot springs | Matt C. Bischoff - Brady's Hot Springs reaches 209*F (and other tidbits)

Finding a Thesis: A Cinder Cone Aside

Just north of Silver Peak on S.R. 265 and just downhill from Mineral Ridge, one of Nevada's most accessible basaltic cinder cones rises out of the low alluvial slopes. The photo, taken from the northeast side of Mineral Ridge, where we made our last stop, shows the basalt cinder cone known as "The Crater" sitting in front of a southern bit of the Weepah Hills, the more distant and linear Paymaster Ridge, and the Clayton Valley playa, with its pale turquoise lithium brine fields.

A Google Earth view of The Crater and associated basalt flow rock. 

The cinder cone is assymetrical, as are many, with a breached east-facing side, where basalt lava flows erupted and spread downslope toward the Clayton Valley playa.

The cone is right beside S.R. 265, just north of Milepost 4, between Silver Peak and Blair Junction (see the map below).

Access to the cone includes a two-track dirt road on the south side and a pullout on the northwest side.

Click to enlarge this location map, the spliced and labeled Tonopah and Silver Peak 30x60 sheets, courtesy USGS. 

I pulled into a flat area on the northwest side of the cinder cone and walked around a little bit, stopping briefly while on my way to elsewhere: In 2010, I was on a loop from Tonopah to the Klondyke mining district to Silver Peak and Mineral Ridge and then back to Tonopah; in 1976, I was leaving Mineral Ridge to go to my next stop in California. Both trips took me past the cinder cone; both trips resulted in my next immediate destination being Blair Junction.

The Crater, looking southeast from its northwestern flank.

The cinder cone—at least the small chunk I saw—is composed dominantly of basalt blocks and bombs and smaller, lapilli-sized fragments.

A basic grain-size classification scheme for tephra, pyroclastic fragments that were thrown out of volcanoes, courtesy USGS.

Almost all the info on the web about this extinct volcano is contained in this one article by the Nevada Bureau of Mines and Geology (NBMG). The most detailed geologic map of the cone and area is here, in Figure 3B, along with a good description of the cone on page 9. This latter citation (Hulen, 2008) has the best reference to the only age date I could find:

“...the basalt has been K/Ar-dated at ~400,000 years (J. Witter, pers. comm., 2008), but this age is at odds with the cone’s barely-disturbed morphology. Accordingly, Witter has submitted a sample of basalt flow rock, clearly sourced from the cinder-cone vent (Figure 3B) for more reliable 40Ar/39Ar age-dating.”

All the other references I found state that the cone is about 390,000 years old without providing credit to an original source.

After parking and getting out of the truck, I walked around for a little while, trying to find some good examples of volcanic bombs. Rather than collecting any hand samples, I took a few photos.

Vesicular basalt.

This hand specimen from The Crater doesn’t show any indications that it was molten or semi-molten when it was thrown out of the vent or when it landed on the cone’s slopes—it is therefore considered a block and not a bomb—but it does show the average character of the basalt: dark-colored and with lots of small to medium-sized vesicles. The basalt is reported to contain phenocrysts of feldspar, hornblende, pyroxene, olivine, and magnetite (Price and Price, no date). I readily identified the small, light greenish olivine crystals in the basalt, though I didn’t get any pictures of the phenocrysts.

Volcanic bomb with a ropy or fluted texture.

The bomb is elongate in shape, and one end is wider than the other. Possibly the narrow end was upward when the bomb fell, still viscous, through the sky.

This could be a bit of flow or cooling texture in a basalt lapilli, but I'm not sure.

A large block of basalt with ropy and vesicular texture.

Am I seeing some aerodynamic shaping in this block, and perhaps some slight breadcrusting? Is this a bomb?

And here's a closer shot.

Here's a bomb with fluted texture, approaching spindly.

I probably should have looked harder for better examples of bombs, and maybe next time I visit, I’ll get around to the far side of the cone—or even up to the top!

A spiny bush and a prickly pear cactus growing on a desert pavement of basalt lapilli, small blocks, and bombs.

The bush looks like some kind of Atriplex or generic "saltbush," but I'm not sure which kind. Any ideas?

We can see the Weepah Hills and bluish Lone Mountain off to the northeast, beyond the dark, lower slopes of The Crater.

Next in this series, we'll head over to California.

Selected References:
Albers, J.P., and Stewart, J.H, 1972, Geology and mineral deposits of Esmeralda County, Nevada [available for sale only]: NBMG Bulletin 78, 80 p.

Hulen, J.B., 2008, Geology and Conceptual Modeling of theSilver Peak Geothermal Prospect,Esmeralda County, Nevada: unpublished report for Sierra Geothermal Power Corporation, 23p.

Price, J.G., and Price, E.M., no date, Cinder cone in Clayton Valley, Esmeralda County, Nevada: NBMG, Nevada EarthCaches webpage (with .kmz downloads available), accessed 18Feb2016.

Spurr, J.E., 1906, Ore Deposits of the Silver Peak Quadrangle, Nevada: U.S. Geological Survey Professional Paper 55, 174 p.

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
Finding a Thesis: Future Stories from the Palmetto Mountains
Lida Summit Roadcut
Finding a Thesis: Next Stop, Silver Peak!
Finding a Thesis: Coming into Clayton Valley
Finding a Thesis: On the Southern Route to Mineral Ridge
Finding a Thesis: The Northern Route onto Mineral Ridge and a Little Geology
Finding a Thesis: Up to the Millsite and Back
Finding a Thesis: Views and Geography and ... Oh, What's That?

Finding a Thesis: Views and Geography and ... Oh, What's That?

And so, we'll leave the millsite and locked gate on the northeast side of Mineral Ridge to get on with thesis hunting outside Nevada, for a change, and ... what's that up ahead? As we round the bend, The Crater, a basalt cinder cone comes fully into view.

The Crater, beyond the metal posts of the old gate.

In the photo above, the low range of hills beyond the Clayton Valley playa on the right is Paymaster Ridge, which we first saw quite a while ago on our way into Clayton Valley from the east. The rest of that hilly, mountainous mess, I mean mass—from directly behind The Crater and northward, to the left—is the Weepah Hills.  The high point in the photo, part of the Weepah Hills, reaches 7753 feet (2362 m).

The Weepah Hills is a more-or-less circular batch of disorganized lowlands, hills, and mountains, with the apparently chaotic to jumbled geologic formations of the area having been horizontally sliced by low-angle faults of probable detachment origin. Tertiary Esmeralda Formation sediments and Quaternary older alluvium cover much of the western part of the hills; a granitic body, the Weepah pluton, probably the same age as the 70 Ma Lone Mountain pluton to the northeast, crops out in a broad area in the northern hills; and a couple small patches of Precambrian Wyman Formation and Reed Dolomite poke through near the central part of the area. The rest of the area is mostly underlain by Cambrian to Ordovician sedimentary formations. Sunshine Mining Company took out a bit of gold at Weepah in the mid 80s; a few other companies have taken a look since then, but so far no additional mining has resulted.

These topo maps show the topography and main features of the area.

The spliced Goldfield and Tonopah 30 x 60 maps (courtesy USGS).

The same map with a few labels.

The whole area shown on these maps is detached.

Here, I've thrown on a few lineaments, including one going up Paymaster Canyon, which gives the eastern side of the Weepah Hills a linear look.

I probably drove straight on down to the cinder cone on my 1976 journey through the area, but on my more recent 2010 photo-taking expedition, I stopped near the old gate to look around at some of the old junk, and to take in the views.

I'm not sure what this old sign said, but it's totally bitten the dust. And it looks like it got run over by a tracked vehicle of some sort.

An old, though not very old, blasting sign.

Beyond the blasting sign, we can see a topographic formation known as The Monocline (this use of a capitalized "The" seems to be quite popular for geographic names in this very local region of Esmeralda County). The Weepah Hills form the broad expanse of hilly country beyond The Monocline, with rugged Lone Mountain forming the bluish mountain beyond that. (Please note that there are several Lone Mountains in Nevada; in fact, I found ten on Trails.com.)

At The Monocline, a thin, dark basalt layer caps soft, white sedimentary rocks, which, according to the Esmeralda County report, are part of the Tertiary Esmeralda Formation. These units have been tilted, maybe as much as 10 degrees.

A closer view of The Monocline and its closer, sister hill, from Google Earth.

Strangely enough, I've never stopped at The Monocline, although it looks like there is a perfectly good dirt road to it!

The Monocline, part of a mine dump, The Crater, and Clayton Valley playa.

The Crater.

A closer look at The Crater is next ... as fast as we can get down the alluvial fan!

Selected References:
List of minerals at Weepah: Mindat.
Weepah Mine: Western Mining History (info last updated in the 80s or 90s).
Weepah Deep: unpub 1989 info from Sunshine Mining Co and FMC Gold.

Weepah Mine in the County of Esmeralda Nevada: unpub 2008 report—much of this info is good, but ignore the Regional and Local Geology sections.

Weepah Reconnaissance/Submittal Summary: unpub 2014 recon report.

Maldonado, Florian, 1984, Bedrock geologic map of the Lone Mountain pluton area, Esmeralda County, Nevada: U.S. Geological Survey Miscellaneous Investigations Series Map I-1533.

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
Finding a Thesis: Future Stories from the Palmetto Mountains
Lida Summit Roadcut
Finding a Thesis: Next Stop, Silver Peak!
Finding a Thesis: Coming into Clayton Valley
Finding a Thesis: On the Southern Route to Mineral Ridge
Finding a Thesis: The Northern Route onto Mineral Ridge and a Little Geology
Finding a Thesis: Up to the Millsite and Back

Hiking Down Glass Mountain

A few weeks ago, we were about to hike back down Glass Mountain after our short hike part way up the glassy rhyolite flow dome. We had taken some overview photos and had stopped at the old working in the foreground (above) to collect some scouring stones. (And then we went off on a float-testing tangent.)

I had vowed to myself, and to MOH, to keep my eye out for some reddish, oxidized glass on the way down...

...and indeed, I found some.

The pile of obsidian and pumice rubble is eroding from a part of the rhyolite flow that includes dense, black obsidian, white to tan-colored pumiceous rhyolite, and reddish brown to reddish orange oxidized rhyolite glass.

I've zoomed in a little here. The black glass looks a little bluish because it's reflecting the sky (what little of it was showing through the clouds).

The oxidized and probably partly devitrified (?) obsidian always seemed to be perched on the treacherously glassy scree slopes above the road we were hiking on. I didn't find any good examples of the orangey rock along the road, and I wasn't about to go climbing over the glassy talus, without sturdy boots and leather gloves.

This rock from in an earlier post shows thin, oxidized bands and streaks, and I'll have to let it stand for a closeup example, although the reddish orange color is not as intense as in some smaller pieces or in the outcrops above the road.

Looking out over the northern dacite flow, and beyond to Timber Mountain.

The photo really captures the blocky and jagged nature of the surface of the dacite flow. It wouldn't be easy to walk across that terrain; one should have very sturdy boots and equally sturdy leather or work gloves. And please don't even consider shorts!

The northern dacite flow is the darker flow area in the upper part of this Google Earth image. The rhyolite flow is the long, almost cylindrical-shaped area emanating from Glass Mountain itself, the small, grayish, round area west and a little south of center.

Read more about the geology in this post.

An old tree grew around a large obsidian boulder (and is therefore younger than the flow). Trees are fairly sparse. 

A geo-type walks down the trail.

Pine trees grow on the angle-of-repose slope, their trunks bent from downhill creep of the colluvium.

I've zoomed in here to take a closer look at a mass of oxidized, reddish brown obsidian near the base of a large, conchoidally fractured obsidian outcrop.

Finally! Down the trail just in time for lunch.

An unreadable metal sign in front of the dacite flow. Maybe it said "Keep Out," once upon a time.

Related Posts:
A Hike Up Glass Mountain
Views from Glass Mountain (and some geology)
Which of These Rocks, Mostly from Glass Mountain, CA, Will Float
The Conclusion of Our Float Test
Hiking Down Glass Mountain (this post)
Links: Pumice and Pumicite

Aerial Views of Two Northwest Volcanoes

My first view of Mt. Rainier out the window on New Year's Day was quite colorful, but the high-order rainbow effect of alternating pinks and greens was due to refraction, from shooting sideways through the Bombadier Q400's window toward the front of the plane.

I waited until Rainier moved fully into view for the next shot:

Photo looking almost due east.

The high peak on the left is Liberty Cap, at 14,112 feet (4301 m); the peak on the right is Point Success, at 14,158 feet (4315 m). The high point of the entire mountain, in the center and back behind the other two, is Columbia Crest, coming in at 14,411 feet (4392 m).

In the view above, we're looking at the head of the South Fork of the Mowich River just left of center in the foreground. The small ice field above and left of the river head is Edmunds Glacier. The shadowed icy mass to the left of Edmunds is the North Mowich Glacier, which is above the North Fork of the Mowich River (mostly out of view).

A radial dike runs from between the two closer and less elevated peaks to the lower right, into what is the headwaters of the North Puyallup River. The landform formed by the radial dike is known as Puyallup Cleaver.

Photo looking a little east of northeast.

Here we're looking almost straight up the andesitic dike that forms Puyallup Cleaver. This dike fed lavas that erupted between 280 and 190 ka (Pringle, 2008). The Puyallup Glacier is to the left (north) of the dike; the Tahoma Glacier is to the right (south). The steep headwall above Puyallup Glacier is called Sunset Ampitheater. Ice in Sunset Ampitheater spills (or flows) into both the Puyallup and the North Mowich Glaciers.

I was on the wrong side of the plane to see Mt. St. Helens, but had this great view of Mt. Adams as the sun went down and the light got pink. Notice the reddish irridescent lenticular cloud off to the side.

Mt. Adams looking almost due east.

Too bad I hadn't thought about my new camera on the Alaska-SeaTac leg of the flight! For some reason, I didn't think about it, and hence only got some not-so-great phone photos.

2015 Top Ten Posts at LFD...

...and—as for 2014, 2013, and 2012—a few more. My rules, as modified from last year:

Because of the vagaries of stat reporting (in this case, by Google Analytics), I'm listing both the top ten posts for the year (in large font, with respective Top Ten number), and the top post for month's without a top-ten posting (non-Ten-rated posts are in a smaller font).

And so, here are the top 10 posts, plus 2 extra, along with a few pretty pictures:

January:

• Cliffs of the Ruby Mountains: Some Pretty Pictures #4

February:

• Things You Find in the Field: Old Sedan #6

March:

• Geo-beers: Volcanic Double IPA

April:

• Dust Storm at the Needles Rocks, Pyramid Lake #3

May:

• Siberian Haze in North-Central Nevada #5

June:

• The Beginning of an El Niño Trip: North-Central and Western Nevada #8

July: No posts in July!

August:

• Too Much Smoke — And Pelicans!

September:

• Way Too Much Smoke: Volcanoes (and Rivers and Ridges) in the Pacific Northwest #1

• Finding a Thesis: Klondyke District #10

October:

• A Hike Up Glass Mountain #7

• Finding a Thesis: Into the Palmetto Mountains #9

November:

• Views from Glass Mountain #2

December:

• Lida Summit Roadcut