A Few Nevada Turbidite References

Crafford, A.E.J., 2007, Geologic Map of Nevada: U.S. Geological Survey Data Series 249, 1 CD-ROM, 46 p., 1 plate [link to pamphlet/description accompanying the map].

Dean, Nicole, Houston, Shauna, and Swanson, Karl, 2002, Geology of the White Pine Mts. along Highway 50, eastern Nevada, 2001 Geology Field Camp: Geological Society of America Abstracts with Programs, v. 34, no. 6, page unknown.

Dickinson, W.R., 2006, Geotectonic evolution of the Great Basin: Geosphere, v. 2, no. 7, p. 353–368; doi: 10.1130/GES00054.1.

Dickinson, W.R., Saller, A.H., 1982, Alluvial to marine facies transition in the Antler overlap sequence, Pennsylvanian and Permian of north-central Nevada: Journal of Sedimentary Petrology, v. 52, no. 3, p. 925-940; doi: 10.1306/212F8094-2B24-11D7-8648000102C1865D [link to abstract].

Fagan, J.J., 1962, Carboniferous cherts, turbidites, and volcanic rocks in northern Independence Range, Nevada: Geological Society of America Bulletin, v. 73, p. 595-612; doi: 10.1130/0016-7606(1962) 73[595:CCTAVR] 2.0.CO;2 [link to abstract].

Keppie, J.D., Boyle, R.W., and Haynes, S.J., 1986, Turbidite-hosted gold deposits: Geological Association of Canada, Special Paper 32, 186 p.

Ludington, Steve, McKee, E.H., Cox, D.P., Moring, B.C., and Leonard, K.R., 1996, Pre-Tertiary geology of Nevada, Chapter 4 in Singer, D.A., ed., An analysis of Nevada's metal-bearing mineral resources: Nevada Bureau of Mines and Geology Open-File Report 96-2, p. 4.1-4.17, 1 sheet, scale 1:1,000,000.

Mattinson, C.G., and Tiffney, B.H., 2001, Terrestrial plant fossils from the Mississippian Diamond Peak Formation, White Pine Range, eastern Nevada: PaleoBios, v. 21, no. 3., p. 1–11.

Theodore, T.G., 2000, Geology of pluton-related gold mineralization at Battle Mountain, Nevada: Tucson, Arizona, Center for Mineral Resources, Monographs in Mineral Resources Sciences, 271 p [link to purchase].

Watkins, Rodney, and Browne, Q.J., 1989, An Ordovician continental-margin sequence of turbidite and seamount deposits in the Roberts Mountains allochthon, Independence Range, Nevada: Geological Society of America Bulletin, v. 101, no. 5, p. 731-741; DOI: 10.1130/0016-7606(1989)101<0731:aocmso>2.3.CO;2 [link to abstract].

A Geologist's Field Book

A geologist's field book is often a yellow or orange, bound or spiral book about 4⅝ by 7½ inches in size, with lined, columned, or gridded paper, often waterproof. The first thing a geologist writes in his or her field book on any given day is the date. The second thing a geologist writes is the place — town, mountain range, mining property, reconnaissance target, township and range (or UTM coordinates if you are using an up-to-date coordinate system), country, county, river, sampling area, name of the field trip you are on — whatever is the most relevant and identifying locality title or place name for that current subsection of your notes. The third thing a geologist usually writes (at least if you were taught back in the 1970’s or earlier) is the day’s overall weather.

Related Geoblogospheric Posts:
Tools of the Trade
Field notebook for the office
Stack of field notebooks
What to Buy a Geologist for Christmas

How to Make Coffee Strandlines or Rhythmites

Once upon a time, MOH and I left suddenly for an unexpected trip of unknown time duration, and I failed to empty all the coffee cups. Upon arriving back, having been gone most of 14 days, I tentatively looked in my cup expecting to find terrible mold, instead finding these lines of coffee deposited around the side of the cup.

"Varves!" I exclaimed, "Except they aren't from yearly deposits, they're from daily deposits!"

I've reflected a little, and asked a few close-at-hand sources, and decided these aren't really varves — and they probably aren't really rhythmites, either — for the simple reason that varves and rhythmites would be layers, of concentrated coffee in this case, that would have been deposited in the bottom of the cup. Instead, these must be more akin to strandlines — or shorelines around a coffee lake, in this case — as suggested by @GeoTheoBO. Other suggestions for what to call these deposits were Stratified Caffineite (@CGKings317), rhythmites (@alexbirtwisle), and my favorite, "Jarves" from "Java-varves" (@Dhunterauthor). Everyone else is welcome to jump into this discussion and naming exercise in the comments.
Prior to deciding that these were really the results of daily evaporation of coffee, I did count the rings. There are 13, with a possible incipient 14th one near the bottom representing the partial 14th day during which we arrived back in time to check the cup. The lines I've drawn above are based not just on the locally fuzzy record shown in that one photo, but on the three photos I took documenting the entire stratigraphic record around the entire inner part of the cup.
Here are the final determinations. A few of the days are a little fuzzy and the lines have been brought in from the side, just like you might have to do when correlating deposits out in the field. Most day's deposits are light toward the bottom and darken upward, possibly reflecting something having to do with diurnal temperature and humidity variations. To be honest, I don't really know when the darkest portion of each day's ring forms, whether at night, during the day, or at some other time. The cup was sitting on the kitchen counter in the sunlight of the window the entire time we were gone; evaporation would presumably have been strongest during the daylight hours, possibly resulting in the lower, lighter colored part of the layer. Any other thoughts?

This post has been submitted to the Bake-Sale Accretionary Wedge (AW#30), though no baking was involved.

UPDATE: Accretionary Wedge #30: the Bake Sale is now up at Mountain Beltway. It's a very yummy Wedge, I might add.

Fold Links

General Fold Info:
Folds at Wikipedia - includes some photos, some general descriptions, mediocre

Folding of Rocks - some examples of fold types, with diagrams, good

Recumbent Fold:
Definition: A fold in which the axial plane is horizontal.

Isoclinal Fold:
Definition: A fold in which the limbs are parallel.

Sheath Fold:
Definition: A sheath fold is a conical fold in which the conical surface is completely closed in the neighbourhood of the cone's apex.

Sheath Folds and more:
Alsop, G.I., and Holdsworth, R.E., 2002, The geometry and kinematics of sheath folds [abs]: Geological Society of America Abstracts with Programs, v. 34, no. 6, p.561.

Alsop, G. I., Holdsworth, R. E., and McCaffrey, K.J.W., 2007, Scale invariant sheath folds in salt, sediments and shear zones: Journal of Structural Geology, 2007, v. 29, no. 10, p. 1585-1604; doi:10.1016/j.jsg.2007.07.012.

Kuiper, Y.D., 2006 ,The usefulness of non-cylindrical (sheath) folds in monoclinic and triclinic shear zones [abs]: Geological Society of America Abstracts with Programs, v. 38, no. 7, p. 19.

Moore, J., C., (unknown date), Shear Zones Ductile and Semi-brittle Zones of Distributed Deformation Around Faults, Especially Strike-slip Faults: "15ShearZones" page from University of California, Santa Cruz, Earth Sciences 150.

Searle, M.P, and Alsop, G.I., 2007, Eye-to-eye with a mega–sheath fold: A case study from Wadi Mayh, northern Oman Mountains: Geology, v. 35, no. 11, p. 1043-1046; doi: 10.1130/G23884A.1.

How to make a sheath fold:
1) Photo of sheath fold exposure (click "click here" for the diagrams).
2) How to make a sheath fold part 1 (then click "continue").
3) How to make a sheath fold part 2 (click "example" to return to the photo).
—Copyright: Dr R. Butler, School of Earth and Environment, Leeds University
—HTML by C. Gordon

(This post continues my ongoing project of cleaning out my drafts folder, which largely consists links collected while doing research of various sorts.)

Friday Fault Photo: Fairview Peak, NV, Fault Line

I captured this Google Earth image of the east face of Fairview Peak, with north to the right and the scale bar on the left showing 4112 feet, and then set about drawing the fault scarp created by the 1954 Fairview Peak–Dixie Valley earthquake. The location of the fault line (in magenta) is somewhat approximate in places, and I've left gaps where the trace is unclear. Identifying the fault line on Google Earth is complicated by the fact that two or more scarps occur in some areas. The line, as drawn, has not been field checked.

An example of the scarp, as seen in an oblique Google Earth image.

The scarp angles across the hill above the loop road near the center, and above the linear road to the left.

Images below are broken into two halves and shown with north to the right (first two images), and then with north up (second two images). These images enlarge fairly well, with the horizontal (north=right) images being best in enlargement and the vertical images (north=up) being best on the blog.

North half of the Fairview Peak strip with north to the right.

South half of the Fairview Peak strip with north to the right.

Two images: north and south half of the Fairview Peak strip with north up.

Can't really say why I did this. I was just fascinated by the fact that you can take Google Earth, rotate the eye view to oblique and — especially after a visit to the area (early December) — can easily identify the fault scarp(s) in most places.

Related Posts:
Where in the West - March
Fairview Peak, Nevada
Friday Fault Photos #6