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)

Rhyolite Porphyry from Majuba Hill III

GSN field trip Day 2: We've taken a few Majuba Hill samples out of the bag.

We'll now take a look at the farthest right sample, having already seen
Rocks #1 & #2 and Rock #3.

One side shows a weathered surface, with dark brown iron oxides and the copper carbonates malachite and azurite.

I suspect that the reason I picked up this rock was because of the mineralized appearance of the outer surfaces. I probably had no idea this rock would turn out to be yet another sample of rhyolite porphyry when I grabbed it off the dump. Scratching the iron oxide reveals it to be goethite mixed with jarosite — according to the old Bear Creek porphyry copper exploration method matching oxide color to a complex triangle of powdered goethite, hematite, and jarosite with mixes in between. The only partial example I can find of this method online can be seen here.

A fresh surface of the same rock.

Zooming in on the fresh surface, we can see that we indeed have yet another sample of rhyolite porphyry: 

Although the former feldspar phenocrysts are nearly completely gone to black tourmaline needles with a scattering of brown iron oxides (goethite + jarosite) and greenish to blue-green copper minerals, the gray, fresh-looking quartz eyes are clearly recognizable.

What's really interesting about this rock is the white to gray matrix.

The matrix of this current hand sample is considerably more altered than that of our previous sample, Rock #3: The matrix is shot through with tiny tourmaline needles and finely disseminated sericite. Additionally, the tourmalinized feldspar sites within this rock contain only minor copper minerals when compared to the feldspar sites of Rock #3. I was a bit surprised at this lesser amount of copper after spying the obvious blues and greens of copper minerals on the weathered surfaces.

And here's another surface of the rock, one showing a moderate amount of reddish brown iron-oxide (hematite + jarosite), a pale bluish green copper mineral (or combo of minerals), and black tourmaline.

The iron oxides are very fine-grained and powdery, and from a few boxworky textures, I'd say that they at least in part replace former sulfides (probably copper sulfides judging by the color of the iron oxides). Quartz phenocrysts are visible in the light olive gray right hand side of the sample (these are easier to see in person with a hand lens than in this photo because of the shadows in the photo).

And that's the last of our rhyolite porphyry samples, at least of those that haven't been brecciated!

Rhyolite Porphyry from Majuba Hill I
Rhyolite Porphyry from Majuba Hill II
Rhyolite Porphyry from Majuba Hill III (this post)

Rhyolite Porphyry from Majuba Hill II

GSN field trip Day 2: we're still at Majuba Hill.

Continuing with our progression from left to right of rhyolite porphyry hand samples, we move on to Rock Number 3, a weakly mineralized version of the tourmalinized porphyry. (Rock 1 and 2 were seen here.)

The feldspar sites in this rock sample contain needles of tourmaline, and powdery white sericite with a soft, blue green copper mineral.

An enlargement of the left part of the same photo.

I'm unclear as to the timing of mineral deposition in the altered, mineralized feldspar sites. Which came first, the tourmaline, the sericite, or the copper minerals (all after the original feldspar phenocrysts)?

The blue, green, and turquoise-colored copper minerals include at least include one spot of azurite, a few spots of possible malachite, and widespread possible chrysocolla — but at Majuba Hill, there are several bluish to greenish copper minerals that might be present (see this mineral list for Majuba Hill), including parnauite and goudeyite, both of which were first identified at Majuba Hill.

Another view of the same rock - this time the right part (turned sideways).

Which came first? I'm still wondering. Maybe we could use some thin sections (not that I have any to offer, sorry).

We'll move on to the highly altered rock on the far right (second photo) in a third episode.

Rhyolite Porphyry from Majuba Hill I

I'm just now getting back to my Majuba Hill series, wherein I'm posting some photos from the spring GSN field trip and some related rock photos. And for those just catching up, the series begins loosely with this first unplanned stop. It then continues with a Keep Out sign, some views of the Middle adit, and some views from the dump at the Middle adit. It then goes on to our first look at the rhyolite porphyry.

What we have today are a few rock specimens — four to start with.

Tourmalinized rhyolite porphyry from Majuba Hill: two fairly "fresh" or unmineralized samples on the left, and two mineralized versions on the right.

The first sample: a weathered surface of tourmalinized rhyolite porphyry. Tourmaline has replaced the feldspar phenocrysts, or filled voids left by the earlier leaching of feldspars, and left only the quartz eyes.

The second sample.

In this second sample, some of the tourmaline in the feldspar sites can be seen to be intergrown with sericite — a very fine-grained, white mica (sericite is usually compositionally the same as muscovite), which in this case formed by hydrothermal alteration.

A second look at the second sample.

The tourmaline mass in the center of this sample contains some reddish brown iron oxides formed after now oxidized and partly leached sulfides. The tourmaline mass below and a little to the right of center shows an example of tourmaline with sericite.

We'll take a look at the next two samples some other day.

Seeing Geology in Patterns

"This month’s Accretionary Wedge topic is “Seeing Geology Everywhere.” Like many geologists, I often see geology in places where there are no rocks. ...

"Do you see geology in unexpected places? Do you often find yourself viewing the world through geology-tinted glasses? Do you have any adorable cat pictures that could be used to illustrate geology?"

     – Evelyn Mervine, Accretionary Wedge #57 call for posts.

Stucco plaster wall texture by Sherrie Thai, some rights reserved.

It began a long time ago: maybe I was about 8 or 10 years old, and I'd stare at the wall next to my bed when trying to sleep. I'd see land masses or continents in the wall texturing, something that perhaps came from my early love of maps and globes, which naturally showed countries and continents. In fact, my brother and I had played a game in the back yard on lazy summer days: while looking up at the afternoon cumulus clouds passing by, we'd name them as though they were foreign or alien land masses of the sky. And then we would play a form of the floor-is-lava game, wherein we'd have to jump from the shadows of the cloud continents in order to not fall out of the sky (because we'd be imagining ourselves on the clouds, not on the ground).

What happens now most commonly, is that I'll be working on some geological problem or project, and I'll start seeing textures or patterns related to certain rocks or maps in floor tiles, walls, trees, clouds, or anything else that happens to resemble some geologic texture or map pattern.

Recently, having spent a lot of time looking at certain hydrothermally altered rocks, I noticed this floor texture that appeared nearly identical to a patchy quartz-sericite alteration style with irregular to wavy chloritic seams.

Enlargement of floor pattern.

Then, while taking photos of clouds the other morning, I noticed this pattern that reminded me of a vein with horsetail structure.

Cloud picture with added lines.

And finally, I often notice a color in the clouds that reminds me of the anomalous Berlin blue birefringence color typical of certain chlorite minerals.

Temperature Readings at Sulphur Works

Continued from this earlier post:

MOH and I went back to Lassen Volcanic National Park about two weeks ago, taking our IR thermometer and a water or snow thermometer. Our intention: measure the sidewalk temperatures near the boiling mud pot at Sulphur Works, and—if possible—get a reading or two of the boiling mud in the mud pot.

The boiling mud pot at Sulphur Works.

Approaching the boiling mud pot area at Sulphur Works.

We approached the mud pot on the sidewalk, taking our first temperature reading 60 feet west of the approximate center of the mud pot. We continued taking several readings, until we were about 105 to 110 feet east of the center of the mud pot. Most measurements were taken at the center of the sidewalk, about half way between the curb and the inner edge. Reading #9 was outside the sidewalk curb, near the outer edge of the reddish concrete of the sidewalk, just inside the black asphalt of the road. Reading #10 was near the inner edge of the sidewalk, just inside the inner curb.

MOH was in charge of our two thermometers and of taking readings, I was in charge of determining our approximate location (by pacing) from the center of the boiling mud pot, and I was also in charge of recording the readings taken.

Looking back toward the mud pot from the area of the farthest reading. The steaming mud pot is just beyond the large whitish area.

  Reading #1,        60' west,   center of sidewalk:           66.1° F
  Reading #2,        35' west,   center of sidewalk:           68.6° F
  Reading #3,        10' west,   center of sidewalk:           74.8° F
  Reading #4,          0' west,   center of sidewalk:           76.5° F
  Reading #5,        25' east,    center of sidewalk:           67.5° F
  Reading #6,        55' east,    center of sidewalk:           98.4° F
  Reading #10,      60' east,    inner edge of sidewalk:    149.0° F
  Reading #7,        95' east,    outer edge of sidewalk:     97.3° F
  Reading #8,      105' east,    center of sidewalk:          107.8° F
  Reading #9,      105' east,    beyond the curb:             128.0° F

The two hottest spots on the sidewalk that we could find were some distance from the center of the boiling mud pot. The first and hottest area—reading #10, with #6 nearby, located about 60 and 55 feet east of the center of the mud pot—was near a little side drainage from which steam was barely issuing. The second hottest area that we measured—readings #8 and #9, located about 105 feet east of the center of the mud pot—was near a small, steaming hole in the ground.

Reading #10 was taken along the inner edge of the sidewalk here; #6 was slightly closer to the center of the mud pot, near the center of the sidewalk.

Closer view of the general area beyond reading #10. 

NOTE: All measurements were taken on the sidewalk, not beyond in this hot, crusty ground. Scalds and severe burns can result from breaking through the ground in the hydrothermal areas in the Lassen area, so we didn't venture beyond the fence.

The ground was steaming slightly in this area near reading #10.

Reading #9 was taken near the outside of the sidewalk pavement, just inboard of the highway; #8 was at this location in the center of the sidewalk.

More growths along sidewalk cracks near readings #8 and #9.

This small, steaming hole in the ground is located inside the fence near readings #8 and #9.

Here we are back at the boiling mud pot, ready to measure the temperature of the mud.

After completing our sidewalk measurements with the IR thermometer, we went back to the mud pot to measure the temperature of the boiling, muddy water. Our first dip of the thermometer, which was attached by foil to a walking stick that MOH hung over the fence railing into the water, was somewhat disappointing: a mere 140°F or so, though we read the thermometer after it was pulled from the water.

We took a second reading near a small boiling area just west of the main mud pot. This time, I captured the reading with the camera: about 172°F. We went back to the main pot, and the camera captured a temperature of about 160°F.

Temperature at the center of the mud pot: about 160° F.

Temperature in a small side pool slightly west of the main pot: 172° F.

Approximate locations of sidewalk temperature readings.

All readings were taken on 21Oct2012 between 11:31 am and 12:02 pm PDT. I regret that I didn't take a GPS and instead relied on my somewhat variable 5-foot pace for locations.

The Sidewalk at Sulphur Works

While at Lassen Volcanic National Park on our first recent visit, which was early last month, we noticed that the sidewalk near the boiling mud pot at Sulphur Works had lots of mineral (and extremophile?) growths in many of the cracks.

Gray, white, and yellowish growths, some of which might be Sulfur crystals.

Closeup of some of the growths.

While bending over to examine these flowery structures or growths, MOH noticed that the sidewalk was hotter than it should be, even for a bright, warm, sunny day. We didn't have our laser IR thermometer handy, so we made plans to revisit the area.

To be continued...

Sulfur (?) at Sulphur Works

Minerals and other growths at Sulphur Works.

Once again we are at Sulphur Works, Lassen Volcanic National Park, on the side of the road near the boiling mud pot, where MOH and I spotted some very neat greenish yellow crystals, which might be sulfur (upper right, center, and lower left).

A somewhat closer view of crystals in the upper right of the first photo.

The crystals seem a little long and pointed to me for sulfur, and copiapite, a sulfate known to occur in the area, usually occurs in scaly masses or crusts, so copiapite seems unlikely.

Greenish yellow crystals from the lower left of the first photo.

Because of the location right next to the boiling mud pot, I couldn't just walk over to examine the crystals. People have been known to break through thin crusts at the hydrothermal areas in the Lassen area, burning themselves, so I didn't even think about it!

Close up of pointed, needle-like crystals.

These crystals may be elongate versions of the Sulfur no. 1 shape shown at mindat.org. If you can't see the java applet at mindat (for some reason, I can't see it at the moment), go here to Sulfur at The Mineral & Gemstone Kingdom; it's the "Sharp Bipyramid" on the right. Or, view the applet at the source, smorf, by searching for, or using the dropdown menu to get to Sulfur. It's the second of the four crystals listed.

Photo examples of similar Sulfur crystals: 1) elongated crystals from the Jemez Mountains, NM, and 2) needle-like crystals at TheodoreGray.com, also shown here.

So, is it Sulfur or something else?

UPDATE 14Oct2012: In the comments, Ron Schott added a similar picture of Sulfur crystals from a fumarole at Nisyros Volcano, Greece, if anything, even more needle-like than these.

Related Posts:
Mud Pot at Sulphur Works
Fumarole at Sulphur Works
Views of Lassen

Fumarole at Sulphur Works

Old fumaroles at Sulphur Works

Here we are, back at Sulphur Works in Lassen Volcanic National Park, having walked across the road to view the current state of fumaroles (as of about 3 weeks ago. The shadowed, small holes above the large indented or concave area, approaching the top of the triangular upper face is where numerous fumaroles have been active during many of our previous visits to the area (visits by MOH and I, only one visit on this blog, with photos from October, 2006).

A couple videos on YouTube (2007, 2010) show the old vent steaming away, and the first one shows just how pockmarked that little hill was with fumaroles!

Active fumarole surrounded by large orange circle

Now we've moved down the road from the viewing area, to get a clearer view of the fumarolic vent that was steaming, that pock-mark in the center of the large orange circle. I suspect the circle may be formed not only by iron oxides, but possibly some jarosite, a sulfate mineral, and some native sulfur.

Close up of the active fumarole

Here we've zoomed in on the active fumarole, a small hole in the ground emanating steam that is no doubt adding to the pervasive, sulfurous stink of rotten eggs.

My video of the active fumarole

One interesting thing about the location of Sulphur Works, including this fumarole and the boiling mud pot across the road: Sulphur Works is near the center of ancient Mount Tehama (or Brokeoff Volcano, as it is sometimes known), a large stratovolcano that was active between about 600,000 and 400,000 years ago.

More Reading:

“Hot Water” in Lassen Volcanic National Park—Fumaroles, Steaming Ground, and Boiling Mudpots - U.S. Geological Survey

Explore the Hydrothermal Areas - Lassen Volcanic National Park

Mud Pot at Sulphur Works

Boiling mud pot at Sulphur Works.

This post is mostly just an opportunity to put up a few quick pictures (and video) from a recent trip to Lassen Volcanic National Park, which MOH and I took a couple weeks ago when I had an extra day off. (Yay for days off!)

It was a clear day, and we drove into the park from the south, taking Highway 36 to Highway 89 north (AKA the Main Park Road), up past the newish Kohm Yah-mah-nee Visitor Center, past Emerald Lake, past the turnoff to Bumpass Hell, past Lake Helen, past the Lassen Peak trailhead, and over the pass a little ways until we turned back around (map of the park).

We had stopped at Sulphur Works on the way up to note the ways in which the hydrothermal activity had changed since our first official visit to the park sometime in the early 2000s. (Earlier visits of mine/ours prior to this more recent era have faded into a distant non-digital past.)
As far as I know, this boiling mud pot came into existence in late 2007, and it grew considerably by early 2008. We remember from earlier trips that the main roadside attraction (besides a side trail that is now closed due to a shifting in the location of hydrothermal features) had been across the road: an active fumarolic area with several vents, and possibly with a mud pot. These fumaroles were barely steaming on our recent trip, though fumarolic activity can vary with air temperature and other factors.

My somewhat shaky mud pot video.

If anyone knows anything more definitive about the history of this mudpot, please let me know.

UPDATE 21Oct2012: Google Street View shows several fumaroles but no mud pot in this location in photos dated 2007.

The Misty Mountains

Four weeks ago, we were driving west over Emigrant Pass on I-80 on our 2nd, and final, U-Haul van trip, when I noticed (I was in my newish jeep, and MOH was in the U-Haul) that the mountains and valleys of the northern Basin and Range were rapidly becoming obscurred by dust.
In this first shot looking southwesterly from a relatively obscure point on Bobs Flat, down Bob Creek toward the Horseshoe Ranch near Beowawe, NV, our view has been dusted, making the visible hills and mountains appear vague, as if lost in a morning mist. The prominent hill in the central part of the photo is a subrange of the northern Shoshone Range, and the cliffy north-facing side of the subrange is officially known as Malpais, but is usually called the Malpais Rim.

The Malpais Rim, site of The Geysers near Beowawe, NV, — the geysers are, sadly, no longer geysing — is "one of several east-northeast-striking, fault-bounded cuestas in north central Nevada" (Eric Struhsacker, 1980). In the photo, the north-northwest facing scarp of the Malpais Rim is facing just a little away from us toward Whirlwind Valley, the flat area on the right side of the photo. Beyond Whirlwind Valley, a farther part of the northern Shoshone Range has an unusually vague outline. We can't see the Cortez Mountains in this dusty view; they are usually visible beyond the Malpais Rim.
Here's our general location (map and link from The National Map, courtesy U.S. Geological Survey). [Btw, all the maps shown here will look better when enlarged by clicking; maps from The National Map can be explored more fully by following the link provided.] Carlin is near the east edge of the map, just west of the U.S. 40 loop through Carlin Canyon (this fairly ancient AMS sheet for the area shows I-80 as partially built, and Highway 40 still in existence before the completion of the Carlin tunnels). Battle Mountain is not far off the west edge of the map.
Zooming in somewhat (map courtesy U.S.G.S. but downloaded from a different part of their website, we can see Bobs Flat, the flat area in the upper center of the map (Highway 40, rather than I-80, is shown on this old 15-minute map), and Beowawe, the tiny town, ghost town, and ranch area on S.R. 306 in the lower left of the map.
Zooming in even farther, we can now finally see the area of The Geysers and the Malpais Rim (The National Map link). I've outlined Beowawe and The Geysers in dark cyan.
A little farther down the west side of Emigrant Pass on the descent toward the Beowawe Rest Stop — which used to be a great place to see The Geysers before their feeder geothermal exploration wellheads were plugged for geothermal production — we see two subparallel slopes comining southeastward off the Argenta Rim in the northern Shoshone Range, in front of the closer and clearer hills east of Whirlwind Valley. These closer, unnamed hills — irregularly north trending — sit between Bobs Flat and the northeast end of Whirlwind Valley.
The Argenta Rim (skewed rectangle) is another east-northeast-trending subrange of the northern Shoshone Range, similar to the Malpais Rim (The National Map link).
Coming into Battle Mountain, I grabbed this shot of the north end of the Shoshone Range near the Betty O'Neal mine in the Lewis silver mining district, in hopes of showing an alluvial fan slope coming off the mountains toward the Reese River Valley, but that slope is barely visible in this grainy, overprocessed photo. Nevertheless, you see the dusty conditions. This dust, and the dust we first saw coming over Emigrant Pass, is coming all the way from the Carson and Humboldt Sinks, located about 100 miles southwest of Battle Mountain and about 120 miles southwest of Emigrant Pass.
Coming around the usually blustery turn at Button Point, I had this view of the southern part of the Santa Rosa Range, with Bloody Run Peak being the high point on the left (south). The high part of the Santa Rosa Range — to the north, and off the photo stage right — was being thoroughly dusted by winds coming off the Black Rock Desert, and was not visible from I-80.

Our next view to the west, of Winnemucca Mountain, meant our second and last U-Haul trip was nearing an end, except for the unloading that took one more day — and except for the unpacking that is still in progress. A few views from Winnemucca Mountain, including one of Bloody Run Peak, can be seen here.

Selected Reference:
Struhsacker, E.M., 1980, The geology of the Beowawe geothermal system, Eureka and Lander Counties, Nevada: University of Utah Research Institute, Rept. ESL-37, 78 p.