Well, it's been so long...

It's been a long time—almost a year—since my last real post, the actual last post being a road song with brief blurb. And even though it's been a year, I haven't really started what would be the last in a series of posts reporting on a trip from Winnemucca to northeastern California, with geology and other points of interest along the route. It's been hard getting to that last post and to a few side posts along the route that would be possible if I would just maintain a bit of focus. And the stumbling block is basically that I'm not traveling that way anymore, at least not routinely: I don't live at that end of the road. Yeah, "the lake" is a thing of the past (which is really sad, especially given the exceptional heat that the summer of 2020 has brought to the northern Nevada area where I currently live).

Anyway, that's a roundabout way of getting around to saying...it's been a long time since I visited the Northumberland caldera in central Nevada. The current isolation of living by myself, social distancing to the extent of hardly seeing anyone who doesn't happen to be in line behind me at the supermarket, and WFH—which I've been able to do so far for exactly two months since leaving "the field" of northeastern Nevada—was starting to drive me nuts, as it does periodically, and I wanted to get away.

Unfortunately, it's been very hot here in northern Nevada (and elsewhere in Nevada, and in many other parts of the west), so though I contemplated going on a brief camping trip, it seemed too hot for that (did I mention the heat?), and the upper campground at Wheeler Peak is closed for renovations (I consider the lower camps to be both too hot and too crowded). So, with the highest, coolest camp in Nevada out of the question, I opted for a central Nevada area that I've been familiar with since 1978: the Northumberland caldera.

Yeah I thought, maybe I'll camp in the highlands, up in the piñon-juniper, but I was unsure of any specific places up there so was sure I'd opt for the more familiar lowlands. Eventually, after much dithering accompanied by equally much grousing about the heat and why it's not a great time to go camping, all the while and nevertheless preparing, then reverting to no it's too hot, then more prepping, then etcetera, off I went.

The trip was a reprise of many, and because of the heat (the highs were around 100°F) I made few stops on my way out to an old drill site atop a location in the northern part of the caldera that we at NEC (Northern Exploration Company) called "The Hot Spot."

The Hot Spot (photo above) is a fairly small mound-like outcrop of welded ash-flow tuff (tuff of Hoodoo Canyon) mineralized with carnotite replacing feldspar sites. At least I think it's carnotite. Maybe it's autunite. That mineralogic tidbit is somewhat blurred by time. I didn't break a single rock out there this time, so didn't check the uranium mineralogy. I did, however, collect a couple nice hand samples of Ts2 and Ts3, formations within the intracaldera sedimentary package.

Anyway, I ended up at the Hot Spot, spent an overly heated night camping in the back of the Jeep, and then I returned via a slightly different route the next day, a partial reprise of trips made in the region as recently as 2012, a time which seems almost as long ago as those first days in 1978.

Things You Find in the Field: Dikes and Drill Holes

After hiking up the north ridge, I wandered over to a flat area that looked like an old drill pad, and found an iron-stained felsic dike at the end of the pad.

Looking south down the dike toward the canyon.

You can follow the dike to a linear outcrop on the middle ridge, and then across the canyon to a rocky patch just left of the darker, more prominent quartzite bed.

Same view, with the dike marked in turquoise.

The casing for the drill hole was still in the ground, verifying that the flat area was indeed a former drill site. I dropped a rock into the hole; it took about 2.5 seconds to hit bottom, indicating a depth of about 30 m (about 100 feet). The estimating method doesn't allow for rocks getting slowed down by hitting the sides of a narrow drill hole, so depths should be considered a maximum. Also, drill holes can be caved short of their original T.D., and a dropped rock might hit the water table prior to reaching the bottom. A splash or funny hollow sound can usually be heard when this happens; nothing can be heard from the rock after it hits water. The sound of the rock hitting bottom is hard to discern in deep drill holes.

It's been quite a while since I tested drill holes of known depth (this can help calibrate how much a rock might slow down by hitting the walls); drill holes now are plugged with mud and cement as the rods are being pulled out, so very few recent holes are left open the way this old hole was.

In the morning...

In the morning after I wake up—while I'm drinking my first, second, and maybe third cup of coffee—I often think of things to write for the blog, how to write them, maybe even what pictures to use.

I also think of things to write while I'm on the way to work, bouncing around in the front seat of a pickup truck (actually, the ride is usually pretty smooth and solid, I just thought bouncing just sounded better). A moving truck is not a great place for writing (there is *some* bouncing), especially because all I have is my semi-smart phone; perhaps if I had a tablet...

My thoughts while riding or driving into work typically run along the lines of...well, maybe it's time for some drilling stories...let's see, there was the guy who yelled and threw things when he was mad at his helpers, which was almost all the time. Ugh. Or, there's a story or two floating around about drill rigs brought onto staked claims in order to make a discovery before the company that owned the claims, thereby being able to, hopefully, make claim to at least some of the already staked ground.

And then, once again, I'm back here at my computer, it's early morning, and the briefest hints of coffee are trying to course through my veins, trying to rev my brain. Ideas are at a standstill; I don't get very far...until I'm back on the road and the ideas start popping. Another story, or general story idea, will come into my head: mud and getting stuck stories. Hey, there's one just over that not-so distant hill! It happened not long ago, and, remarkably, I have a few photos for it! And not too much farther down that road and over the next hill or two to the south, there's a mud without stuckness story...and that leads to a more typical claim jumping story...which leads to another claim jumping story out of sight from this road but down a road I was writing about last fall and winter before I got distracted by our recent move.

But then, I'm sure I'm missing something...maybe it's the details...because when these ideas start while I'm on the road (any road will do, me driving or sitting as a passenger, either way), other ideas come in and crowd out and confuse the first ideas, which then sometimes include other people's stories: other accounts with drillers, other encounters with mud, other overstaking problems. Which story to tell? What details to use? And, without a tablet, and even with a small notebook, how will these stories make it from barely incipient idea to fully written account?

One story would be about the driller (and set of helpers?) that got thrown off a job down in the south-central Mojave one spring (I hope it was spring and not summer) for showing up to work drunk and carrying a small flask of whiskey or JD. The driller that came to replace him had an interesting time using one of the two only pay phones in town—and so did I, although I used the other of the two pay phones in town—but the guy that had real problems with the one pay phone, which was sitting there on the corner of Main Street and the cross street that formed the junction that made the town, was one of our claim stakers, who was out there running a soil grid across the claims he was staking. And his problems with the pay phone had something to do with the druggy nature of the town, the drugs being the second main reason for the town, the first reason being the intersection of two sub-major (major in the Mojave) roads.

And so the ideas come and go, just like that, while I'm sitting here in the morning partly coffeed up, glancing constantly at the clock so I won't be late: sometimes the ideas get written down, sometimes they don't. These kinds of stories generally don't have photos to go with them, and the Mojave stories are not likely to have photos any time soon or in any systematic fashion: collecting the photos would take almost as long as the original years of exploration.

And now, with one last chug of ever-so-good nice-and-hot coffee, I leave this post behind and start getting ready for work.

SW to SWxS of Center: West Northumberland Canyon

In our backwards trek away from The Geographic Center of Nevada, we've reached one of the last stretches of dirt road prior to the start of our now long ago January day in the center and south-center of the Northumberland caldera. And what stretch of road would that be? That would be the Northumberland Mine Road, the section running from the mouth of West Northumberland Canyon on the west side of the Toquima Range, east and up West Northumberland Canyon past the springs, the old barite mine, and the Northumberland gold mine, to Northumberland Pass. Beyond the pass, the road continues eastward, down into East Northumberland Canyon, past another old barite mine (the larger of the two, both of which operated in the 1970s and 1980s), finally ending at the Monitor Valley Road about 7 miles southwest of our last stop.

Compass Card, on Wikimedia Commons

by Denelson83

The mouth of West Northumberland Canyon, up on the west pediment of the Toquima Range, is about 27 miles southwest of center; the springs are about 26 miles southwest by south (SWxS or SWbS) of center; Northumberland Pass is about 27 miles south-southwest of center (see Boxing the Compass).

I had planned to post this section of our trip — that is, the entire Northumberland Canyon section, in one post — but due to limited editing & writing time (I did my initial editing of this on a funky phone while riding one of the better (read: smoother) buses back from a day's work at the mine) — I'm now posting just the first part: West Northumberland Canyon from it's western mouth to just below the springs. The second part will post in a few days.

After returning from our 5 mile excursion up some canyon near Mt. Ziggurat, which we'll hopefully see later, we hightailed it north on the range-front road, turned right on the Northumberland Mine Road, and entered West Northumberland Canyon. (MSRMaps location of the area.)

Northumberland Canyon cuts southeast through the northern part of the Northumberland caldera, a large caldera about 21 miles in diameter that erupted a moderately large volume (15 cubic miles) of rhyolitic quartz-sanidine ash-flow tuff about 32.3 million years ago (McKee, 1974a). The canyon wall is cut into typical exposures of the typically goethitic golden brown, strongly welded Northumberland Tuff, which usually shows intense vertical fracturing and imperfect columnar jointing.

Driving up the canyon, one can see a good deal of geology related to the formation of the caldera, including large, often irregular, and at least sometimes internally brecciated landslide blocks of often dark gray to black Ordovician Vinini Formation (Ov).

A couple of the smaller slide blocks or masses are shown in the photo above; these particular masses are apparently at least partly contained within welded tuff.

The reddish hill in the distance to the north is capped by the tuff of Hoodoo Canyon, K-Ar dated at 31.4 Ma (McKee, 1974b). The reddish portion of the hill is underlain by moderately to strongly welded tuff; a black vitrophyre can usually be found near the base of the upper reddish zone, above a white, relatively thin, poorly welded zone. The tuff of Hoodoo Canyon (Hoodoo Canyon is the canyon north of West Northumberland Canyon), overlaps and rests on intracaldera sediments (what we called Ts2 through Ts4; what was sometimes called Ts5 turned out to be the poorly welded portion of the tuff of Hoodoo Canyon). These intracaldera sedimentary units were deposited on the Northumberland Tuff and on the Ov landslide blocks in an irregular intracaldera moat lake that may have been deeper on the north side of the caldera, resulting in a sedimentary package that was thicker to the north (it was thinner to the south, or maybe partially to entirely eroded in places).

The fractured dark brown to black mass capping this hill of golden brown Northumberland Tuff on the north canyon wall, is one of the larger Ov landslide masses or blocks.

Several of the largest of the landslide blocks and masses occur close to the mouth of the canyon. At least one near the canyon mouth can be seen from the road, others can be reached by hiking north of the road. Several, if not all, of the dark patches and outcrops in this MSRMaps airphoto are landslide blocks or masses composed of black chert of the Ordovician Vinini Formation (Ov). I keep saying landslide "masses" and not just landslide "blocks" because we found from mapping and drilling that many or most of the masses join in what is probably a basal layer to the intracaldera sedimentary section, a unit we called Ts1. A couple of these larger masses can be seen in the first photo here and the second photo here.

Here's a somewhat closer view of the irregular contact between the same Ov landslide mass sitting on top of the Northumberland Tuff. The internally brecciated fragments of the black chert in Ts1 are often glued or welded together, presumably from the heat of the tuff beneath it. Where drilled at depth, the angular to subangular breccia fragments are sometimes rimmed or cemented by pyrite. In places, the brecciated Ov landslide masses or layers look more like cemented talus deposits than landslide blocks.

In the central part of the caldera, these intracaldera landslide or talus deposits are thinner and are overlain by a later pulse (or more than one pulse) of Northumberland Tuff, which in the central part of the caldera show strong welding and compaction foliation like the tuff in West Northumberland Canyon. This upper part of the Northumberland Tuff correlates with what we called Ts3 in the northern intracaldera moat sediments: an ash flow or series of ash flows that flowed into the intracaldera lake, retaining some semblance of ash-flow tuff in places, and looking more like disrupted ash-flow tuff or even waterlain air-fall tuff in other places.

And now we've arrived at the springs in West Northumberland Canyon.

References:
McKee, E.H., 1974a, Northumberland caldera and Northumberland Tuff, in Guidebook to the geology of four Tertiary volcanic ceters in central Nevada: NBMG Report 19, p. 35-41.

McKee, E.H., 1974b, Road log to Austin-Northumberland caldera-Carver Station, in Guidebook to the geology of four Tertiary volcanic ceters in central Nevada: NBMG Report 19, p. 3-5.

Related Posts (in order of posting):
The Geographic Center
South of Center: Potts Ranch Hot Springs
South by West of Center: Monitor Valley Salt Flat or Dry Lake
Backroads: Too Cold to Change a Flat, and other Considerations
SW to SWxS of Center: West Northumberland Canyon - this post

SWxS to SSW of Center: the West NU Canyon Springs and Northumberland Pass - a coming post

Report on an Afterwork Field Trip

This will be a brief field trip report from an undisclosed place and an undisclosed time. In fact, other such field trips over the years, whether during or after work, might be worth reporting on occasionally, mostly sans photos.

It was a sunny afternoon, approaching early evening, and several colleagues and I passed by some broken and brecciated road cuts while on the way to our various evening destinations, wherever they might have been. The purpose of the rather spontaneous mini field trip was to shoot the bull about the meaning of the road cuts and see if we could figure anything out—in other words, to get our creative thoughts flowing. Lines and crude cross-sections were drawn in the dirt on the side of the road, with less crude versions drawn in some field books.

Our first stop was essentially a mess of fractured, broken, and shattered rocks showing varying degrees of iron-staining and oxidation. Some jarositic-looking, weakly clayey limestones formed a possibly arched, upper zone above more typically calcite-veined dark gray Devonian limestone cut by hematitic seams and hematitic fracture-fill fines. Discussions ensued about what iron-oxides were staining the rocks and filling in fractures. A reddish coloration—reddish brown to reddish orange brown—in a batch of rocks, sometimes present in broad areas or even over whole mountains, is supposed to be a good sign when one is looking for the upper oxidized to leached portion of a porphyry copper system — at least according to a few old-timers who told me about such things back in the late 1970s when porphyry copper exploration had come to a standstill after what turned out to be a long-term decline in the price of copper.

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An Aside: A long time ago, Bear Creek or Minefinders developed a color triangle for determining the composition of various limonites or generic to mixed iron-oxides. Powdered pure or nearly pure jarosite (a sulfate containing iron that can form as a weathering or oxidation product of pyrite) was placed in a circlular spot in the upper corner of the triangle, powdered pure goethite was placed in the lower left corner of the triangle, and powerdered pure hematite was placed in the lower right corner of the triangle. Three other circles were placed between the three corners, each composed of 50-50 mixes of the appropriate two of the three main powders, and one circle in the center contained the three end members mixed together. To summarize the triangles main colors, jarosite is pale yellow to white when powdered or scratched, goethite is the typical dark golden brown of the average "limonite," and hematite is its typical reddish brown. I've looked high and low for an online version of this field cheat sheet that consisted of stiff cardboard with clear plastic- or cellophane-covered circles of powders with appropriate labeling, but have yet to find anything resembling the original. Perhaps I'll draw up something similar to the original and go further into this little exercise in crude field determinations sometime at a later date. For now, back to the field trip.

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I developed a question or two as we were standing beneath the large fractured to brecciated mass of structurally complex reddish to yellowish brown pile of carbonate rocks: (1) were we looking for copper and (2) doesn't the same guide to ore (red rocks and reddish color anomalies) also apply to finding porphyry molybdenum deposits? I also wondered (3) haven't red rocks been considered a guide to ore in at least some disseminated gold districts, for example at and around Florida Canyon? The answers: (1) maybe [seriously, what we were looking for was actually in question], and it is good to define what you are looking for without getting so stuck on what you've decided to look for that you can't see the possibility of finding something else, (2) yes, for sure, something I first learned from other not-quite old-timer types, also back in the late 1970s, and (3) well, of course, but not everywhere.

Our impromptu field trip then moved down the road to stop number two, where a breccia of unknown origin was exposed in a particularly hairy road cut on a tight curve with narrow shoulder and the occasional speeding vehicle. The breccia reminded me of the Titus Canyon megabreccia: mostly angular fragments of dark-colored carbonate rock were cemented by white, crystalline calcite. I thought it looked like a breccia of possible hydrothermal origin, one in which fragments had shattered but not moved far. It also looked a bit like a tectonic breccia, though no faulting surfaces were exposed. The expounder leading this part of our field trip said it could be a collapse breccia that formed over an oxidized massive sulfide deposit. Oxidation of sulfides produces volume loss, leaving a potential collapse waiting to happen. I'm not sure how the calcite gets into position to cement the breccia together, it somehow having to push the fragments apart to exploit the collapsed zone, but some long, thin beds of shaly limestone could be seen to be sagging downward in a couple places, testifying to possible collapse. Perhaps the breccia was really fragment supported instead of apparently matrix supported, in which case the calcite could have moved in later with groundwater or low temperature hydrothermal waters of some kind.

Resulting major questions arose from the two field trip stops and all the bull that was being shot around. One major one that was oft repeated: Should we drill here? Or there? Or over there? Everyone wanted to choose their own drill hole or two and locate them in specific favored spots. Another question: Should we sample here? The answer to that question? If you have to ask the question and don't just pile in with your bags, labels, and rock hammers, the answer is an automatic yes. Conclusion: get on with it! ASAP.

And so ended a spontaneous early evening field trip to two undisclosed field trip stops, along an undisclosed highway, at some vague undisclosed time within the last 10 to 30 years.

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Torrent, José, and Barrón, Vidal, 2002, Diffuse Reflectance Spectroscopy of Iron Oxides (see page 1441 for Munsell color of some iron oxide minerals).

Somewhat Related Posts:
Some Thoughts on Weirdness, and A Picture (or Two) (or Three)
Megabreccia II: More Photos
Megabreccia III, the Continuing Saga

Things You Find in the Field: Old Drill Rig

While wandering around in the Mojave Desert of southern California a couple years back, in an area where I've done some gold exploration, MOH and I came across this old drill rig sitting next to a dilapidated and abandoned trailer. The trailer has what I consider typical Mojave coloring; that is, it has a bit of pink as trim. Of course you can find pink-trimmed trailers anywhere, but because of a bunch of rundown and often deserted, tiny adobe shanties along the Amboy Road near Twentynine Palms, many of which were painted pink at last viewing (like this one), I tend to associate that color with Mojave structures of all kinds. Note the creosote and Joshua trees: yes, it's the Mojave. Also note the volcanic rocks of the Hackberry Mountain mining district in the background. (Location: MSRMaps; Google Maps will only take you this far.)
Many of the old rigs you find out in the field, either in fields, deserts, or along the roadside, are old water well rigs, often cable-tool rigs. I can't really say for sure if that's what this is: none of the pictures I found online match exactly, though the cables hanging from the rig and lack of an apparent top-head drive make me suspicious. If anyone knows for sure, please comment!
The cab of the truck is quite colorful.
I can't make out a phone number, in case you're in need of a rig.

Related Post: Mid-Monthly Art: Mojave Hilton, located in the nearby Vontrigger Hills.

Barite from Goldfield

Continuing down the pallet at Goldfield, NV, I spotted this huge rock made almost entirely of barite.
This is hydrothermal barite, not the bedded barite often mined for barite drilling mud (with Nevada being the largest producer in the U.S., and third after China and India worldwide in 2008).
Here's a closeup photo showing nice orthorhombic barite crystals coated with tiny druses (quartz?). Barite is often first noticed because of its high specific gravity – it's very heavy compared to other minerals and hand samples – and it doesn't fizz in HCl the way calcite and limestone do.

I've got some nice barite crystals from the Northumberland gold mine, tucked away in a box somewhere. The particular small pit my crystals came from has long since been mined.

More About Barite:
Jewell, P. W., 2000, Bedded barite in the geologic record: SEPM Special Publication, v. 66, p. 147-161 [link to abstract].

Jewell, P. W., and Stallard, R. F., 1991, Geochemistry and Paleoceanographic Setting of Central Nevada Bedded Barites: Journal of Geology, v. 99, p. 151-170 [link to abstract].

Nevada—2007: USGS Minerals Yearbook, Volume II, Area Reports: Domestic.

Rossi Mine - Barite, Elko County, Nevada – with photos of bedded and crystalline barite.

Goldfield series so far:
Headframes of Goldfield
Alunite from Goldfield
Pyrophyllite from Goldfield
Barite from Goldfield (this post)
Enargite from Goldfield

The Unlikely Gradational Stratigraphy

I described the problem briefly in my last post about drilling at the Northumberland caldera: the volcanic formations and intracaldera units of waterlaid volcaniclastic and volcanic deposits — from the post-caldera Hoodoo Tuff, down into the intracaldera sediments, then into the caldera-forming Northumberland Tuff below — had sharp to relatively sharp contacts in the field. The chip boards from the previous year's drilling, however, showed gradational contacts from top to bottom — with Hoodoo Tuff chips present from the top all the way down, with chips of the uppermost unit 6 of the intracaldera sediments present from the beginning of unit 6 all the way down into unit 2 and below that into the Northumberland Tuff, and so on. At first examination of the chip boards, I simply didn't know what to make of the apparent change from sharp to gradational contacts, and thought that possibly it was the result of sloppy chip-board construction. Upon close examination, however, I finally realized that there were rock types from the top of the hole present all the way down to the bottom of the hole.

This kind of contamination is usually bad for sampling and assaying, but because we were looking for uranium, we were relying almost completely on a calibrated gamma-ray probe and not planning to do much assaying. Still, I wondered why the drilling was resulting in such strong contamination. The conventional answer, so to speak, was that we were using conventional rotary drilling, not reverse-circulation rotary drilling. Conventional rotary can easily result in contamination because the rock chips from the bottom of the drill hole come up the outside of the drill stem, and can pluck chips and material from rocks and formations above the bottom of the hole, all the way to the top. Reverse-circulation rotary drilling prevents this by having the chips go up the inner tube inside the drill rods, where the chips can have no contact with other rocks the drill has already drilled through.

I arrived on the Northumberland caldera drilling project, somewhere southeast of Austin, Nevada, and generally due east of Kingston Canyon — where I happened to be staying in a company-rented tiny cabin — in the fall of 1979. At first, we had a couple core rigs and one rotary rig running. I asked the rotary drillers how they usually did the sampling, and they told me that they usually laid out piles of chips and ground up rock for every 5-foot interval, in a nice line on the ground. Having been told to "ask the drillers," I thought, okay — odd, perhaps, but okay. After they laid out the chips in these nice, neat little piles, I was supposed to put them into the sample bags that I'd labeled. ("Hole 1, 0-5" or something like that; maybe we had a scheme, it's not one I remember.)

Now it's kind of awkward, even under the best of circumstances, to grab handfuls of piled, ground-up rock and somehow get them into 7 x 12½ white sample bags — and these weren't the best of circumstances. When I came back early the next morning to start bagging up samples from the first drill hole, I found the mounds of chips frozen into solid, cone-shaped piles, with the piles frozen to the ground. At first I kind of freaked, like OMG I should have done this yesterday, I am so screwed, etcetera. Yeah, the sun melted them later on — way after noon — but this sample-layout method really put a kink in things (at least for me). It was fall, and temperatures were prone to drop below freezing at night in the high valleys of central Nevada, suggesting that chip freezing would be an everyday occurrence.

I talked to the drillers and asked them if they could just put the samples into the bag instead of piling them up so neatly on the ground. They hemmed and hawed, indicating that they didn't *do* that. I told them we'd have to figure something out, because their on-the-ground method wasn't going to work unless my company was willing to wait around for next summer to get the samples. They finally agreed. I don't remember that it was hard to convince them, and I don't know whether they'd *done* that before, or were just trying to slip something by me. I have seen piles of chips lying out in nice lines as recently as 2005.

Okay, that problem is solved: the drillers are putting the samples in the bag. I'm numbering the bags — which is still a common but not always thing for a geo or tech to take care of — but they are sampling! Yay!

Now, let's watch what they are actually doing. On a conventional rotary rig, one that happened to not to have any kind of sampler or cyclone or splitter, the chips come up the outside of the drill pipe and just pile up on the ground around the hole. The drillers drill 20 feet of steel down at a time: that's the length of each piece of pipe. Every five feet, the helper (only driller and helper on the rig in 1979, not a third person for sampling) sticks a shovel into that pile and puts the stuff into one pre-labeled sample bag.

The pile around the drill hole just stays there, always being contributed to by more stuff coming up the outside of the pipe. Every now and then, when the pile is deemed too large by the driller, the helper pushes some of it aside with the shovel. I watch this process for a short while (having not seen it the day before), and eventually, between rods, tell them about the problem: every single rock type that has been drilled is still lying there in that pile every time the helper sticks a shovel into it to get the next 5-foot sample. Oh sure, the bulk of what goes into his shovel is the most recent stuff that came out of the hole — the stuff on the top of the pile — but not entirely. No wonder the formations glued to the chip boards from the previous year looked gradational.

I point out to them that they are taking a sample of everything that's come out of the hole for the last couple hundred feet, not just the last five. No, they insist that it's just most recent stuff, they are careful and just getting what is near the top. I tell them that it isn't really working that way, though, even if they think it is, and that I'd like them to clear away — with the shovel — that pile every five feet.

Well, no, they can't do that, they are on a footage contract and that would slow them down, having to stop every five feet to clear the pile away. They would be glad to clear the pile away every rod — every 20 feet. I tell them I really can't tell what the rocks are with all that stuff mixed together (although I sorta can, and the down-hole logs are diagnostic for many of the intracaldera contacts), and I tell them that the assaying will totally suck (although maybe we won't be assaying much of anything — and we didn't say "totally" like that back then, and maybe I used another cuss word, and maybe I hadn't fully developed my talking-to-drillers attitude or technique, which includes just the right cuss words at just the right time).

They finally agree that the helper can take a sample with the shovel, put the sample in the bag, then clear away all the rock debris that's piled up during five feet of drilling. It's not perfect, because the drill keeps drilling — or maybe it stops like it should, but I lost that bit of detail somewhere between then and now — but it's so much better, and the not-supposed-to-be-gradational contacts return to the clean sharpness that we'd mapped in the field.

And that's why you should never ask the drillers how to do the sampling.

And that's why it's a good idea to answer a young geologist's nagging questions, even if they seem really dumb to you.

And that's why you should have an hourly contract rather than a footage contract with your drillers: then you can slow them down anytime you want, and they can't bitch about it. (They might still bitch some, because a good driller wants to make footage, but a good driller should also recognize the importance of the sample he's getting.)

Drilling Stories: Getting Started at Northumberland

Last fall I didn't make it out to the high country, or much of the low country, before the snow fell, so I've left off the sequential history-of-exploration posts. I'll jump ahead to something in the future of the Caliente-camp stories already told, and also in the future of other summer-of-1978-camp stories that are yet to come in that timeline. And so, to where and when should I jump?

Because I'm low on photos, I think I'll tele-transport to a time and place for which I have few photos. That is, I have a few old pictures of drill rigs and people from that time, but I don't have many, and I have fewer still that might be crucial to explaining the stories. And so it goes.

Once upon a time, I was assigned to my very first drilling project by way of being reassigned from a project I was already working on (another story entirely). I inherited this already-in-progress project in the middle of my second summer at Northern Exploration Company from another young geologist who was no longer working there. I inherited chip boards from about 10 conventional (non reverse-circulation) rotary drill holes. Possibly no core holes had been drilled at that time; possibly a few had, but if so, I don't remember them. I do remember, in immense detail, staring at the chip boards from those several already-drilled holes, studying them, comparing them to the down-the-hole electric logs and gamma ray logs, trying to glean as much info from them all as I could, trying to reconcile the chip boards to the formations I knew well from mapping those same formations the year before (mapping was done by myself and several others), and trying to come up with reasonable and good drill sites with which to continue drilling.

— NOTE: Chip boards were used prior to the invention of plastic chip trays. We spent our days, while out on the rig, gluing drill chips onto strips of plywood that were designed to hang in warehouses after logging was complete. We made the chip boards on the tailgate of my company Bronco; each plywood strip may have shown 100 to 400 feet of drill hole, depending upon the space reserved for each 5-foot interval. The photo to the right is a different kind of chip board, made from small pieces of material left from core drilling. A photo of a rotary-hole chip board can be seen here in Figure 1.

Why was I staring at the chip boards so intently? Was there a problem? One problem was that the chips going down the hole showed a gradational stratigraphy from the upper formation, the tuff of Hoodoo Canyon, through several well-defined and distinctive intracaldera units, to the lower formation, the Northumberland Tuff. On the ground, these formations were easily distinguished, one from the other, and though faulting proved to be a problem in correlating stratigraphy between some holes, the stratigraphy was fairly simple.

Another problem? I couldn't seem to get anyone to tell me much of anything about running a drilling program. "Think you can spend this $500,000 by the end of the year?" Well, who can say no to a question like that? Uh, when is the drilling scheduled to start? In the fall. Is there time to spend that much money? Yes, but not without getting several rigs. Can we get permits for road-building and drill sites by then, can we get roads and drill pads built by then, and how do you go about getting permitting and flagging roads? Yes, yes, and figure it out yourself.

The project was almost unimaginably large to me at the time. I had never before seen a drill rig, and didn't know exactly what I would be doing out there. I knew I should be concerned about the sampling, and understood from my graduate Exploration Geology course that there were several sampling intervals and procedures that I should probably choose between.

Aside: A rock hammer lost in 1978 could be in this photo (above). If you spot it, let me know. On the other hand, it could have been washed away in the flash flood of 1979.

Finally, one geologist—slightly older and a couple years more experienced than me—told me to sample on five foot intervals. That's a standard sampling interval for this kind of drilling program, but everyone else had left me guessing, and it had seemed like pulling teeth to glean this minuscule amount of information. Others probably thought the answer was obvious, contained in the chip boards of the earlier drill holes. What about sampling procedures, numbering systems, and size of bags to use?

"Oh, don't worry about it. The drillers will know what to do."

We had a name for this syndrome—the incomplete question answering and lack of explicit instructions—long before the end of the first year (the Caliente year). We called it, "Give them enough rope so they can hang themselves." The they that might get enough rope for hanging was us; those who might give us enough rope were our bosses. I didn't invent the name for this syndrome (the name being the quote) . The name was invented by the geologist who had the drilling project before me—Jay, I'll call him—a male geo, slightly younger than me, who had been on our 1978 crew from late Caliente to Deer Lodge and onward.

Problem two, the sampling interval: solved. What about problem one, the unlikely gradational stratigraphy?

Questions about Drilling

I've been asked a few questions about drilling recently, so I'll attempt to briefly clarify a few things. First of all, not all my work entails drilling, though certainly many non-drilling phases of the exploration work I do is designed to create drilling targets so that we can find some ore. For a couple looks at what I do in general, refer to these two posts, and also browse the blog using some of the tags I use, or by using the search bar in the upper left corner (those are semi-efficient ways of navigating the blog).

The two linked-to posts are attempts to cover what I do, but they are by no means thorough, and they haven't been updated with more recent posts. Short version is this: I'm a minerals exploration geologist — my work ranges from generating reconnaissance targets, staking claims (that part is usually handled by staking or surveying companies) or aquiring properties through negotiations, property evaluation in general (which can include evaluating a lot of existing data or creating new data by sampling and assaying or by running various types of geophysical surveys), mapping the geology and generating drilling targets (or not, as the case may be), drilliing said targets and hoping to get the property past a first stage, on to a second or third stage, thence onward to the time when a property can become a mine and go into production. I've also helped evaluate companies (or their properties) as part of company acquisition negotiations.

As a minerals exploration geologist I've never been near an oil rig, nor have I worked offshore (although I'd like to visit an offshore rig). I've worked almost exclusively in metals, mostly in copper, uranium, and gold, not necessarily in that order. When I log chips, rather than core, it's called chip logging. I've never seen mud logging and don't know how it differs from chip logging, but the chips I log are washed clean of mud other than fault-gouge clay or alteration clay, and they have been sieved (through a large kitchen strainer) prior to being put into plastic chip trays that hold 20 intervals (usually 100 feet).

I almost never take drilling samples while running a drilling program, whether I'm the only geologist on the program or whether I have an assistant geologist (or partner) working with me. The drillers are supposed to do that — although when I first started in the business, one set of drillers was particularly poor at collecting the samples, so I gave them some training, while getting some training myself: it was my first project. I have more than one post in draft stage about this first drilling project.

I almost always work either with rotary rigs or core rigs. These typically are capable of drilling to a couple thousand feet or more, depending on the power of the rig and the depth of the target. When I started, reverse-circulation (RC) drill rigs were rare or non-existant, and so we used conventional rotary rigs. RC rigs are standard, now, for most non-core drilling.

When I first started working around drill rigs, it was customary to have two men on the rig: the driller and the helper. Now, RC rigs usually have three men, and core rigs often have two, sometimes three. I've seen one woman on a drill rig over the years: a helper (rod man) on a core rig. The third guy on the RC rig is specifically there to take the samples, and nowadays, to make the chip trays. It became standard to have this third person sometime during the 1980's. Prior to that, geologists may have taken samples in order to get good samples, and the geologist made the chip boards and later the chip trays (these were invented sometime in the 1980's).

I have rarely had to be at or "on" a rig the entire time it was drilling. Drillers usually work 12-hour shifts; I usually don't. Sometimes, when a rig is about to get done with a hole, but the target depth is flexible (not set beforehand), I will need to be there to "call" the hole, that is, end it. That can mean being at the rig until they quit in the evening (usually at 6:00 pm) and then, if the hole needs to keep going, also being there when they start up in the morning (usually at 6:00 am). With a single 12-hour shift — which is more common on exploration rigs in the middle of nowhere than on rigs near mines, but is by no means standardized in either locale — I've usually not had to be there every morning at start up and every evening at shut down. I've often been able to run myself on a ten-hour day.

The only drillers I've seen that worked less than 12-hour shifts (more like 8 to 10), have been drillers on rigs that are more typically used for environmental-type drilling, such as what Short Geologist might be describing here.

Many RC and most core rigs will run two 12-hour shifts, in which case a geologist might be required to answer a cell phone in the middle of the night, although I've done that only rarely. A 24-hour rig will often need to have more than one geologist around, trading off night calls and other tasks. It's often possible to let the rig drill through the night, barring unforeseen and usually undesirable circumstances. Back in pre-cell days, if a rotary rig was running two shifts, a geologist might have had to go out and visit the rig if it looked like it might need down-hole logging or "calling" in the middle of the night. I did that a couple times a long time ago. Core rigs, which have usually run two shifts, don't generally need to be visited in the middle of the night because their drilling rate is so much lower than rotary rigs, usually a third to a tenth.

I hope that covers some of the questions I've been getting, both here on the blog and via email. My recent post about drilling was probably somewhat vague.

UPDATE (4/21/2010): Be sure to see Short Geologist's most recent post about drilling, for a look at what she does.

UPDATE (4/23/2010): Chuck posted a link to a neat, back-of-truck, core-logging setup he used last year. My trucks aren't usually that large!

Related Posts:
Drilling Stories: Getting Started at Northumberland
The Unlikely Gradational Stratigraphy

Rig Sitting in General

I've been in the field recently — in an unspecified location — and every now and then I think of things to write for the blog, or photos I could post, but it's often been either too windy — or sometimes too snowy, or too windy and too snowy at the same time — to write anything down. I am able to write field notes in my field book: field books don't blow away, and Rite in the Rain books don't run or get messy, especially if one uses a Rite in the Rain pen. In fact, it's been mostly too windy to work on the field-based cross sections I've started.

And why would I even have time for writing? Whether an in-field, drill-sitting geo has time for cross-sections, paperwork, mapping, air-photo mapping, report writing, or other writing depends on the setup of the drilling program. For some types of projects, the drillers don't fill little twisty-tie sample baggies for me, nor do they always make chip trays. When they do, I can examine the contents of the baggies filled with rocks, chips, or other material at some distance from the rig, or I can log the chip trays on the tailgate of my truck (or in the cab, not really preferred unless the weather is completely nasty : or in a core shack or office). There are some advantages to watching the drilling as it goes down (so to speak), especially on a smallish project or a project where one is still feeling out the sampling methods or drilling company. If I'm present, I can observe the drilling recovery first hand, for example, rather than relying on the driller's reports (daily logs).

Because of the logistics of the current project — which I won't describe — I'm unable to sit in the cab of my truck at some distance from the rig, away from the noise and diesel exhaust. Consequently, I'm wearing my PPE, which includes ear plugs, hard hat, and boots. Retreating from the rig to some distance is my preferred method of sitting a rig, if indeed a rig needs sitting. Not all rigs do. They generally need to be checked on now and again, and samples need to be picked up (by techs or geos), and occasional troubleshooting or budget watching is usually necessary — but those things don't always require full-time rig sitting.

In the Field Again (Take Two)

Yes, I'm in the field again, as many of you have gleaned from here and there (and elsewhere) updates and postings.

The field in this instance is a fairly short drive from our little house in the hinterland of eastern Nevada, and the field is an all-day outdoor affair. Although I nominally work a 10 hour day, with drive time and meetup-with-the-drillers time, it's more like an 11.5 hour day on many days, less on some, more on others. I'm left with scant time for blogging and other communication, but we'll see how it goes. I have some drafts that I might be able to post, and possibly I can post some other things depending on evening, morning, and weekend time.

I've been working an unusual 6 on and 1 off schedule, modified this week to 5 and 2 in honor of the Easter weekend. With the extra spare time, I'll be able to drive MOH to his winter mountaineering area without having to leave at 5:00 in the morning. I'll also have enough time - I hope - to get my taxes done.

Reminds me of a song:
In the field again, I got to get back in the field again, the life I love is in the field with my friends...

Two Years Ago Today: Two Drill Rigs

Two years ago today, I went out early in the morning to visit two drill rigs. This is the first drill rig. They are fairly deep in the hole, but we'd like to go deeper.
The shadows were long, and although there was frost here and there, the ground wasn't frozen. Neither drill rig was inside an active mine; they were conducting brownfields exploration around the edges of an old pit.
When I arrived at the second drill rig, the sun was still low on the horizon with the frost unmelted in the shadows.
The rig had twisted off in bad ground at less than 200 feet, leaving a lot of pipe in the hole. The driller, who had been on shift with his crew since midnight, was not happy.
The front end is jacked up to level the rig on this slightly non-level drill pad.
While I was there, the driller shut the rig down prior to trying to get the twisted-off steel out of the ground. If you know how many pieces of pipe were on the truck to begin with, you can figure out how many are now in the hole.
This is some of the miscellaneous equipment and paraphernalia near the sampling side of the drill rig.

I stayed on site for most of the morning. It turned out that both rigs were going to need to move to start new holes, with neither having reached the target depth, and I had to show them the new sites and make sure the drillers were okay with the sites.

Two Years Ago Today: Drilling Inside the Pit

A couple photos from an early morning visit to an exploration drill rig inside an active mine. The sun was just coming up over the east wall of the pit, about to blind us. Mud on the bench floor is from a water truck passthrough to keep dust under control.
The pit was busy, as pits often are, with haul trucks going back and forth from the shovel, just in front of the rig. The driller was being annoying because I said to keep drilling. (Hey, it's his job!)

One Year Ago Today: Drill Steel and Ice

One year ago today, drill steel lying around in the snow had little crystals of ice, from frost...
...and was sparkling and glittering in the early morning sun. It was very cold. In fact, the official low that morning was 9° F (-12° C), according to the Weather Underground, and it was probably colder on the drill site. Average low for March: 22° F; record low in March: -13° F in 1952. Average high in March: 50° F; record high in March: 73° F in 1966.
Ice was lying around everywhere (as apparently were Brunton compasses), forming crystals and little ice ponds.
The ponds, essentially frozen puddles on the dirt roads I drove around on, were not large enough to ice skate on.

This year has probably been a bit warmer than last year; but then, I haven't had to go out at sun-up to check drill rigs. We have had plenty of snow recently, although possibly not as much as last year. For the current temperature of where I am, right now when this post posts, check the sidebar.

What I Do: Previous Post Links Version (PPLV)

This post is another attempt to show what I do, again, partly in response to Phizzle Dizzle's question, WTF do you do? What I've done here, is to link to already created posts that address this question at least in some way. This also organizes some of my posts in a format useful for me and maybe for others.

• Field work: Field Camp.
• Field work: Finding a thesis area, part 1.
• Field work: A bit on helicopter work.
• Field work: A few rules of the desert.
• Field work: Getting stuck and unstuck in mud.
• Field work: A bit about field schedules.
• Field work: An old field camp and a bit on people.
• Field work: A 'lost' gold mine.


• Geology Tools: My first Brunton compass.
• Geology Tools: At work and in the truck.
• Geology Tools: Just standing around.


• Exploration: Is this mineral a guide to gold?
• Exploration: How to find gold in Alaska - ha!
• Exploration: The people and the companies.


• Drilling: Some old drill sites.
• Drilling: A little bit on getting drill sites ready.
• Drilling: More on getting drill sites ready.
• Drilling: Logging rotary cuttings or chips.
• Drilling: A stuck rig.
• Drilling in winter 1: Too much snow.
• Drilling in winter 2: Very cold.


• Close encounters 1: Two mountain lions.
• Close encounters 2: One snake.
  

Friday Field Photos #3

The road in: the Northumberland Mine Road

Just a few quick photos from my first drilling project. Above, the photo shows the long, somewhat winding road in to Northumberland Canyon, which heads east off of old Highway 8A (now Nevada S.R. 376) a couple miles south of the turn off to Bowman Creek, and which goes through the north part of the Northumberland caldera.
Drill site number one is on top of the orange-colored hill. The old Bowman Creek camp is way in the distance across Big Smoky Valley, on the east flank of the Toiyabe Range, just behind the left part of the orange hill.
Drill site number two is at near the base of the white, tuffaceous cliff on an inconspicuous flat area above the bushes. The white cliff is just below the vitrophyre (not basal but close to it) of the Tertiary tuff of Hoodoo Canyon, the orange-brown welded ash-flow tuff forming the top of the hill. The same volcanic formation makes up the orange hill in the second photo.

These drill sites, and many others, were drilled a long time ago by a company that doesn't exist in the same form that it existed in back then. Back then, well that was the late 1970's, and we were drilling for uranium in the second uranium boom. (There have been, so far, exactly three uranium booms - not sure how the current one is doing.) We drilled with conventional, non-RC rotary rigs (and core rigs) in the days before reverse-circulation rotary rigs were standard on exploration drilling programs. Sampling was not considered a problem because we probed the holes with a down-the-hole logging tool that measured gamma and total counts, and also gave us a bunch of electric readings (S.P., resistivity, and conductivity, I think). The down-the-hole logs were almost enough to do the intracaldera stratigraphy without even looking at the rocks, once I had looked at the rocks and logs long enough to figure out what the Hay they meant.

Ah, those were the days? First drilling program, not knowing a darn thing about anything! But we did dance next to the drill rig; I'm not sure I could really put a picture of that up here, though! Nowadays, dancing would be considered unsafe, and we would be considered almost too young. Maybe I can dig up a photo of a late night by the fire: drilling went into a very cold, icy, but mostly snow-free December.

To My Wayward Drillers

To DD and DR - if you happen to be making it in to Los Anchorage on your days off and have access to the vast world of online communications...

Now that you are both up north, what do you expect us to do down here? Train more drillers? I don't think it's fair at all, our best being taken, as it were, just because there are problems in the northlands!

So hurry back, we are all awaiting your return! In the meantime, enjoy the late summer weather for a few more days. Termination dust fell in Anchorage more than two weeks ago! It will shortly be cold, snowy, 20F below zero and colder, and the ground will be frozen. Of course, I hear it can be better to drill on frozen rather than muddy ground, and the mosquitoes, no-seeums, and white socks will go away. Along with the bears. I hope you have good dog-houses built around your rigs!!

If you are in Anchor Town in the next couple weeks, drop me a line, we can have coffee at B&N, or maybe you can buy me a beer or two - surely you owe me at least one (each) for leaving so suddenly!

Best wishes from down here in the southlands, I'll be heading from Outside to Inside soon,

Yours, sfx
Otherwise known as Your Drilling Commander-ess (ha!)

Austin: Is it Time to Leave Yet?

So, you're still in Austin, at The International? Remember you can check out anytime you like...

Wait, that's for the Mojave, what am I thinking?

While you're here, enjoy some music, lose a few bucks in the slots. (I swear those didn't used to be there.)

The International is a relaxed, friendly bar, where anyone can find a spot.

Upwards-facing horseshoes for good luck are popular in Austin these days, as are those ever-proliferating signed dollar bills on bar walls. I think this fad started in Middlegate, and now that fad is starting to overtake The International, which I personally find to be a shame (reprehensible?) in such a nice, old bar. If you look very closely at the gun hanging from the ceiling, you'll see that "International Hotel" is carved into the stock. And what's that below the BudLight sign?

Ah, it's a pool table. Time to shoot some pool - reminds me of the good-old days, shooting pool at The International: C. and I would stop in after dinner, after our 10 to 12 hour field days driving all over the entire Millett 2° sheet. That summer, 1977, we worked 12 days on, 2 days off, drive on company time (thankfully!).

On your way out of the bar, check out the *awful* bar picture on the wall over the window. I think that painting has been there for a long time. Reminds me of an old story.

The story goes like this. I was shooting pool during a drilling party, wherein the drillers take you to town and buy all the beers. Sometimes a drilling party happens as a celebration that the drilling is over, other times it's just a random thing. If you happen to get involved in a drilling party, remember that when the drillers buy another round, it doesn't mean that you have to keep up with their rate of drinking. Simply put the coldest (freshest, newest) beer in front of the other half to quarter-finished beers, which you have already placed in a line on the bar counter. Always drink from the coldest one, unless you are drinking something like Guinness, or unless you like warm beer. The drillers will bitch and moan about this for a short time: stick to your guns and they'll settle down, and they'll continue to buy all the rounds.

Anyway, for this particular drilling party, Austin was a good 1-hour drive away from where we were actually staying, which was in Kingston Canyon - I actually have no idea where the drillers were staying, probably in some trailer out in the middle of the valley or pulled into the now defunct (gone, burned down) Frontier Station. The night was getting on - it was getting later and later. I was shooting pool at The International with two other geo-types, RL and DMC, and our expediter, BobS. My field assistant, a young woman, had disappeared - which is an entirely separate story.

The bartender and bartendress, his girlfriend, were taking care of the bar. He was a round-faced guy, possibly in his mid-thirties, a few years older than my late twenties age. The bartendress had been getting a little wild, and got up on the bar as though she was going to start a strip dance.

The bartender, who was the owner, immediately walked over to the front entrance and closed and locked the door. We were locked in! He then jumped up on the bar with his girlfriend, took off his shirt and jeans, and started dancing on the bar in his shorts. It was a strange sight. Really strange. We stared for a couple minutes, then went back to our pool game. He was dancing on the very same bar you see above. (Yikes! Although no one said yikes back in those days.) End of story (E.O.S.) - except for the long, dark drive back to Kingston Canyon.

Possibly by now, you are feeling lost in Austin. Well, don't worry - you can leave. It's not the Mojave. You don't even have to return, but you probably will.

You'll return because, after all, there are only so many places to stop on Highway 50 - for motels, for food, for beer and pool. After losing one too many pool games, or after getting your fill of beer at the bar, wander on up to the Toiyabe Cafe for dinner: burgers, shakes, steaks, and other good food. It's not Alice's Restaurant - which was in Silver Peak, by the way - so you can't get everything you want, but you can get many things, including bottomless iced tea, espresso, and thick espresso-chocolate milk shakes.

An especially good thing about the Toiyabe Cafe is that they are open for breakfast by 6:00 am, in case you want to get an early start in the morning.

UPDATE 3Feb2012: I no longer recommend stopping at the Toiyabe Cafe: diners change. Eat at The International instead. I can't, however, predict how things will be next week, next month, or next year.

Notice that the sign on the wall pointing to the beach is pointing west. That either means the beach is on the Pacific Ocean, or is an old shoreline in Lake Lahontan (or it's a beach at Lake Tahoe?). It certainly doesn't mean the nearby Reese River!