Monday, January 18, 2010

The Eureka Quartzite at Lone Mountain

I initially started this short series on the Eureka Quartzite in order to show two locations where you can see this famously clean orthoquartzite from Highway 50 - and you can see it without getting out of your vehicle, no less! The first locality is Lone Mountain, Eureka County, Nevada. (Remember, there are at least two Lone Mountains in Nevada; this one is *not* in Clark County and is thankfully miles and miles from Las Vegas.)
You can stop at the Antelope Valley Road turn-off on the the south side of Highway 50 anytime of year, unless the mud or snow is too deep, to see this view of our favorite quartzite. We're looking north; the Eureka Quartzite is the white cliff near the western base of Lone Mountain (the lower left).
In this closer view, the Eureka Quartzite is the bright white cliff below a cloud shadow, and at least part of the reddish cliff below that. I no longer have the excellent drawings and photos I made when first visiting this area with Dr. E.R. Larsen's Geology of Nevada class in 1975, but the general geology can be seen in this air-photo from an earlier post. Warning: contacts drawn on the photo are approximate and interpolated, not necessarily precise or exactly correct.
Dirt roads pass below the quartzite cliff near the top of the alluvial fan, providing access of unknown quality. It's been years since I've driven to the base of the cliff, so I can't provide any road reports.
You can see Lone Mountain for at least twenty miles when driving from west to east on Highway 50, across the wide, open expanse east of Hickison Summit.

As alluded to in an earlier Lone Mountain post, GEOLEX indicates that the Eureka Quartzite does not have a type locality. It was first named by Hague in 1883 for exposures within 50 miles of Eureka, and was further defined and described by him in 1892. In 1933, Kirk proposed that the section at Lone Mountain be recognized as the type locality, because exposures near Eureka are inadequate or incomplete. Nolan and others (1956) described the quartzite as "everywhere thoroughly fractured or brecciated because of extensive faulting; and in many places it has been recrystallized as a result of mineralizing solution." The USGS accepted Lone Mountain as the new type locality (Nolan et al, 1956), and now the Lone Mountain section is generally used as a defacto type section, or, as GEOLEX states, a "standard section."
Now you see it... you just barely see it.

Some References:
Hague, Arnold, 1883, Abstract of report on the geology of the Eureka district, Nevada: U.S. Geological Survey, 3rd Annual Report of the Director, pp. 237-290, plates 24, 25.

Hague, Arnold, 1892, Geology of the Eureka district, Nevada: U.S. Geological Survey Monograph 20.

Iddings, J. P., 1919, Biographical Memoir of Arnold Hague, 1840-1917: National Academy of Sciences Biographical Memoirs, Part of Volume IX.

Kirk, Edwin, 1933, The Eureka quartzite of the Great Basin region: Am. Jour. Sci, 5th ser. v. 26, p. 27-44.

Nolan, T. B., Merriam, C. W., and Williams, J. S., 1956, The Stratigraphic Section in the Vicinity of Eureka, Nevada: Revision of the pre- Tertiary stratigraphy of east-central Nevada: U.S. Geol. Survey Prof. Paper 276, 77 pages.

Eureka Quartzite and Lone Mountain Posts:

Considerably more geological references can be found throughout the earlier posts.


Garry Hayes said...

You bring back vivid memories of the day(!) trip we took to Lone Mountain in 1984 from UN Reno for the paleontology class. A long, long day, but collecting the Paleozoic critters was fun.

Dr. Jerque said...

That Quartzite is very nice for sure, but my favorite Lone Mountain is the big one outside of Tonopah.

Also, did you know that some have speculated that the Lone Mtn barely outside of Vegas is part of a huge landslide?

Silver Fox said...

Garry, all the UNR field trips were great! Fond memories.

Kyle, I was thinking there were three Lone Mountains in Nevada, wasn't sure about the one near Tonopah, and didn't look it up. It's a very different Lone Mountain than the one above - and perhaps is my favorite also, just because it seems to be a core complex. I haven't spent as much time in the Tonopah one, however. Several days at the Eureka one.

I've driven by the Lone Mountain outside Vegas, have never stopped, didin't know it might be part of a landslide.