Looking For Detachment

Things You Find in the Field: Fauna on and near Rocks...OR...on and amongst the Flora

2013-05-24T04:50:00.000-07:00

Blue belly lizard near some foliated andesite (this is the Great Basin Fence Lizard, or Sceloporus occidentalis longipes).
(click any photo to enlarge)

The lizard was rather skittish, and I couldn't get very close.
Read more about blue bellies in an earlier post.

A lizard of unknown denomination running over a lichen-covered outcrop.

A very small gray and white bird perched on a gray rock
atop an iron-stained outcrop (upper right).

Two shining leaf chafers or "Little Bears."

AKA Paracotalpa granicollis, a kind of scarab beetle.

Ladybug!

And finally, a meadowlark atop a sagebrush.

I hear meadowlarks often, but am not always quite so lucky as to see them. This time, I was crossing a muddy little stream by a meadow, on my way to take the long way home (I didn't know it was *such* a long way, but oh well) when I heard this one singing.

Fault Breccia on Slickenside Ridge

2013-05-21T04:50:00.000-07:00

Up above our last hiking stop on Slickenside Ridge, MOH and I came across this wonderful exposure of a breccia (hiking stick for scale).

Here's a closer view, showing massive and drusy quartz cementing the breccia and filling vugs left in the rock.

This is a type of fault breccia — though I was so into my admiration of the breccia that didn't think to look for the fault — and you can see hints of slightly oblique slickenlines on the smooth upper surface in the first photo.

In fact, it just occurred to me to show you what I mean, so here are two photos of that upper surface, one without drawings, one with.

Planar fault surface from the 1st photo, enlarged.

Same photo with some lines drawn in.

The possible slickenlines in the upper left are the ones I noticed first; the second possible slickenline direction shown in the lower right is vaguer, might be my imagination. More field work required!

A zoomed view of the "best" part of the breccia.

Looking northwest toward Winnemucca Mountain (hidden from view by my choice of framing).

Now I've walked back over to the spot where I left you in the last post, looking down Water Canyon toward the northwest. Just above the bright reddish orange dike rock on the right side of the photo, on the hill across the canyon, you can see the lower part of a rock wall first mentioned in this early post about the dikes.

Looking back down the hill and across the canyon.

And so now, as we turn to head back down the hill, we might think about investigating the rock wall on the far hill, the one we sometimes call "Dike Hill."

Views from the Field: Humboldt River Basin

2013-05-19T09:40:00.000-07:00

I've been out in the field on a fairly routine basis recently, taking pictures mostly of rocks and my hammer (for scale). Occasionally I take a photo or two looking off into the distance, or of other non-work items (like lizards) that I come across.

This photo looks more or less southwest across the southern part of the Humboldt Range, with the green, irrigated fields of the lower Humboldt River basin a few miles below Rye Patch Reservoir and just above the Humboldt Sink in view off in the distance. Location of the Humboldt Sink linked below.

The interesting shape of the juniper wood is what really caught my attention!

Slickenside Ridge #3

2013-05-14T05:00:00.000-07:00

Coming up Slickenside Ridge past the last little slickenside, we came upon this whopper.

It's hard to tell from this photo, but fractured, brecciated, and slickensided dike rock on the far side of the fault plane is juxtaposed against more dike rock, which is what I'm standing on to take the photo. The fault is dipping more or less to the east, and the slickenlines are almost straight downdip (slightly oblique).

A closter view of the lower part of the slickenside.

An even closer view of the lower part of the slickensided surface.

Using the the direction of some of the steps in the slickensides in these photos, I deduce that the motion is normal, with the east or outcrop side down with respect to the west side. This direction would be expected in a Basin-and-Range setting, but the observed steps don't face uniformly upward, so I can't be sure of my interpretation without further work (offset of beds across the fault would be ideal).

We also noticed a nearby cross-cutting fault of minor displacement running about east-west, offsetting this fault and the faulted dike-dike contact by a few feet. Apparent offset across this cross fault was south side to the east (the fault was poorly exposed and dip direction wasn't obvious).

View of "Dike Hill" across Water Canyon.

We made it up to the notable first juniper tree, and stopped to look across the canyon at the dikes, which were blogged about here, here, and here.

We viewed the hill again a little higher up, from this little shadow created by an outcrop of quartzite.

We then hiked up to our final outcrop and this view of Winnemucca Mountain (on the left beyond the town of Winnemucca) and the Santa Rosa Range (the bluish mountains on the far right).

Our hike wasn't over, though...

Slickenside Ridge #2

2013-05-09T04:50:00.000-07:00

A small set of slickensides, with slickenside float above, on Slickenside Ridge above the last locality, this time in quartzite only.

Looking uphill toward more dike rock, green grass, and blue sky. Quartzite is deep in shadow on the right.

What else will we find?

Slickenside Ridge #1

2013-05-06T05:00:00.000-07:00

Slickenside Ridge is our personal name for a narrow ridge south of Water Canyon, south of an area that MOH and I sometimes call "Dike Hill." Here we are looking across toward Dike Hill, with a face of slickensided, slickenlined quartzite in deep shadow on the right. The contacts between the quartzite and the porphyry dikes, discussed most recently here, seem to be faulted almost everywhere on the lower part of Slickenside Ridge.

Slickensides on quartzite.

Slickenside with slickenlines; hand for scale.

I've reached over to place my hand in the photo, while trying to maintain my camera at verticality.

Slickenside and slickenlines; no hand for scale.

Now I've tried to maintiain verticality without having my hand in the photo. The outcrop was difficult to photograph because of rocks. The first photo not in shadow (second photo above) shows a less oblique, nearly downdip apparent orientation of the slickenlines than the photo above where I was trying hard to get a photo of the true orientation. Not really sure which photo reflects reality better, but I do think the slickenlines were somewhat oblique. (Too bad I don't usually hike with my Brunton!)

Gratuitous shot of spring wildflower: a buttercup, possibly this buttercup, also seen here, though they all look about the same to me.

Things You Find in the Field: Pyramidal Objects #3

2013-05-02T05:00:00.000-07:00

A few years back, while out taking a set of roads that makes a large loop starting from Highway 50 at either Garnet Hill or Ely, going either northeast or north and then going west, then heading north and west some more, and then running back south to Highway 50 at the Thirty Mile Road junction, MOH and I ran across this wooden pyramid at Summit Springs near Piscevich Summit (MSRMaps location and also see the Google Maps Location at the end of this post).

A closer view of the wooden pyramid.

Even closer.

I really don't know what this type of structure is used for, but went inside to take a look.

Inside view: a metal pipe runs up one wall and out the top.

Another inside view.

Possibly this small structure was used as a smoke house? (And although I don't see a lot of coating of the walls by creosote, some planks look darkened.)

Inside looking out toward a tree near the spring.

A second inside-looking-out view, this time past tree No. 2 toward the broad curve into Bothwick Creek canyon, which runs off to the north (right).

Things You Find in the Field: Pyramidal Objects #2

2013-04-29T07:05:00.000-07:00

"Danger. Explosives."

I'm presuming from the sign that this metal, pyramidal object once contained explosives. It's location seemed random: it sat on uneven ground amongst some rabbit brush and sagebrush, near one small juniper tree and some scattered, irregular mine dumps.

Set of rungs or handholds going up one side.

It was sturdily built: notice the rivets or bolts lining the edges of the metal sheets. This type of structure is atypical compared to the usual sorts of powder magazines or powder houses I've run across in the field before, which are more often dug into the side of a hill, sometimes consisting of a short adit with a sturdy metal or wooden door, and sometimes being a small, dug-in room or building like this one found in Tonopah or this one from the Matchless Mine in Colorado.

No rungs on the opposite side.

The inside.

Inside, the metal can be seen to be riveted or bolted to sturdy, wooden crossbeams. The wooden floor was a bit worn, and pack rats had been using the area.

Things You Find in the Field: Pyramidal Objects #1

2013-04-22T05:00:00.000-07:00

Quartzite on top of "Dike Hill."

I came across this small, pyramidal rock on top of the hill seen first in this earlier post about dikes and drill holes. I didn't know what its full shape would be until I walked over to it, having gotten a glimpse of it from below. The first view made it look like a nearly perfect, small Pyramid of Giza.

View showing all sides.

Yes! It's in the shape of a pyramid, in this case a right, rectangular (not perfectly square) pyramid, a little eroded and lichen-covered on its more northerly sides. Pretty well-formed for a rock, eh?

Crude Map of Some Porphyry Dikes in Water Canyon

2013-04-19T04:45:00.000-07:00

A couple days ago, we were looking at some rhyolite porphyry dike exposures, mostly on the north ridge of Water Canyon, an area MOH and I hike every now and then.

Google Earth image of the area (north to the right).

Crude map of the dikes.

On this second Google Earth image, I've added the approximate extent of the rhyolite porphyry dikes in bright turquoise. Contacts should be considered approximate. The south end near the canyon appears to be complicated by a fault as shown in dark blue, and that slope, although mostly of porphyry, appears to contain either beds or blocks of quartzite, possibly caught up within a couple merging or anastomosing dikes.

Across the canyon farther to the south (left edge of the image), a thin bed of quartzite is shown in blue running along one edge of a dike. I'm not really sure that the bed correlates directly with what looks like another thin quartzite bed directly across the canyon from it to the north (right). Also along that southern edge, a single turquoise line marks the east extent of another dike area. I'm not really sure what is going on between that line and the blue quartzite line, but those rocks look more like sediments or quartzite than dike rock in Google Earth.

What might not be clear from the image is that at least one, and maybe two or more, intermediate to mafic dikes of unknown age cut across the switchbacked road east of the rhyolite porphyry dikes of presumed Tertiary age.

What appear to be pieces of intermediate to mafic dike rock, with associated greenish outcrop in the road just behind my hand.

The intermediate or mafic dikes or sills look slightly reddish brown on enlarged images.

Google Earth image with approximate trace of one intermediate or mafic dike added in bright green.

Google Earth image showing approximate areas of rhyolite porphyry dikes hachured in bright turquoise.

In the last image, sans intermediate or mafic dikes, I've added hachures to make it more clear where the rhyolite porphyry occurs. Again, the areas just north and south of the canyon are rough approximations of reality, and all contacts as drawn represent my best estimation, having been followed in part in the field and filled in using Google Earth.

Things You Find in the Field: Screwy Contacts?

2013-04-16T04:40:00.000-07:00

While wandering up one of our hiking hills back in mid-March, I noticed some orangey brown rocks that at least in part seemed to be cutting across the general trend of beds in the dark, brownish gray quartzite. Are these dikes? Maybe just some slumping or sliding of large boulders? Or maybe it's just the angle of my view.

For the first photo, I'm standing between the first switchback and the first large outcrop of quartzite (next photo). The first switchback is at Location 1. Locations 1 through 8 are identified in the final Google Earth image at the bottom of the post.

View from higher on the hill, looking across the canyon.

Now, having rounded the bend of the first switchback and made it up a very rocky jeep trail, I'm standing in the shadow of a large, jutting outcrop of quartzite [Location 2]. A narrow bed of quartzite holding up a ridge across the canyon runs parallel to some vaguely orange-brown, scrabbly-looking or blocky-weathering material [at Location 8].

We wander past more quartzite, hoping to find our mysterious, unknown rock around the bend. Really. That's what we do on hikes.

Aha! A pale yellowish to light brown rock in contact with our darker, brownish gray quartzite! Right there in the road!!

The rock above the road on the skyline is made of the same stuff. What is it? [Contact is at Location 3.]

It's a dike rock!

What I hold in my hands is a white to pale grayish yellow to moderate yellowish orange and light brown rhyolite porphyry with conspicuous quartz phenocrysts.

Now I'm standing on the dike above the drill pad [Location 4] from a day or two ago, looking south across Water Canyon [Location 8]. A fuller explanation of what we're looking at can be read here, with contacts drawn in.

From that same perch just above Location 4, I look west across a field of orangey brown outcrops of more of the same rhyolite porphyry, toward the dark brown quartzite knobs [Location 5] near the west end of the road.

Here's the view from the quartzite knobs [Location 5] seen in the last photo, looking east up Water Canyon and across the same field of dikes and quartzite outcrops [toward Locations 3 and 4].

Most of the exposures in this photo, saving ones in the foreground and a few on the far left and right (and on hills in the far distance), are of rhyolite porphyry.

An unexpected rock wall [Location 6] cuts diagonally across the photo, running from the foreground outcrops of quartztite to a couple middle-ground outcrops of porphyry. In the previous photo, the wall had looked more like a dike. Trust me when I say it isn't! (More on that later.)

Having reached our hiking and geologizing goals, we'll now head back down the hill.

From the middle of the hill, we look down toward Water Canyon across a few bouldery outcrops of orange-brown porphyry and dark gray quartzite [at about Location 7], with more massive exposures of quartzite lower on the hill.

Now we've arrived back at the first switchback [Location 1], and I realize the outcrops below it are made of porphyry.

What we see directly across the canyon at Location 8 is mostly porphyry, with a couple thin beds of quartzite running straight up the ridge.

Looking back to the north from just across the canyon.
(This photo is from a hike on a more recent day).

The first switchback [Location 1] is just right and uphill of the bold porphyry outcrops on the slope just above the trees. These outcrops of mostly porphyry seem to contain a few blocks or beds of quartzite, although I haven't walked the area to know for sure. The orange-brown outcrops on the far skyline left of center include the exposure at the drill pad [Location 4] that we saw in the earlier post. A couple irregular dikes cut across the middle hill, connecting the switchback exposures to the drill pad exposures.

The contacts don't seem so screwy when you know what's going on!

Google Earth image of our area, with north to the right.

Numbers of locations referenced in the post.

Accretionary Wedge #56: Landscapes as seen by a Geologist

2013-04-13T08:40:00.000-07:00

Accretionary Wedge #56 is all about geologists and photographs, as explained by Andrew Alden, our host:

Once upon a time, you took a picture of something that lots of people photograph. However, because you are a geologist, it didn’t turn out the way it does for most people. Show us that picture, tell us what you see in it, and tell us about the way you take pictures.

I take a lot of photos. I can't begin to tell you how many rolls of film I used to carry with me for simple 3-day field trips back in the day of Kodachrome, but I can easily shoot a hundred or more digital frames in a day, the number being limited only by the number of gigs on my SD card and the percent charge on the two proprietary rechargeable batteries I carry with me: one in the camera, one in my pocket (except for yesterday, when I forgot the extra).

So, I take a lot of photos. I think about how I'm framing them when I'm shooting, about what will look good as a photograph. I think about what I'm seeing, about what the photographs might show myself and others. Mostly I just shoot, as many photos as possible.

I see a lot of landscapes and roadcuts when driving here and there (which is something I do a lot of). Sometimes the landscapes are like nice, wide, almost blank spaces to me, allowing my mind to roam or think non-stressful thoughts not generally related to life or work; other times I really contemplate the landscape and notice the shape of the hills, pediments, basins, and mountains, and I perceive or try to imagine or understand the way the landforms formed and evolved, how the rock formations are guiding the shapes in the land. I see contacts and faults, real and hypothetical, wherever I go.

Consequently, when I take a photograph — almost anywhere unless it is indoors or of people (and sometimes even then) — I am seeing something that isn't necessarily visible to non-geologists, and I see that something in the photo, even when it isn't obvious. The photographs I shoot often already have contacts and fault lines drawn and visible in my mind, and the erosional or depositional remnants of geologic time are jumping out of the scenery and into the frame. The landscapes and rocks are telling me their stories, even from a distance — sometimes they nearly shout their stories, sometimes they almost whisper. Either way, their stories are embedded into my photographs.

A fairly bland landscape photo looking across Rye Patch Reservoir.

In this photo, taken partly for the nice clouds and the inscrutable but interesting shapes of the hills in the lowlands across the reservoir, Majuba Mountain (AKA Majuba Hill) clearly stands out as a resistant, rather roundish knob.

View Majuba Hill in a Larger Map

I took no less than 12 photos of this hill as we drove by on our way to catch a plane. The place fascinates me, partly because I've never been there, and in large part because I know it's supposed to be a great mineral collecting site, with ores of copper, tin, uranium, gold, and silver and various minerals including torbernite, cassiterite, and tourmaline (read more here). There is also supposed to be at least five varieties of breccia. The knob is resistant and in the shape it's in because its a complex rhyolitic or granitic plug, and because of the attendant alteration that includes silicification. I see all that when I drive by, and all that shows up in my photo, at least when I look at it. But really, I've never been there, though I've had it on my list of places to visit for a very long time.

My last post shows an example of the contacts I see when I take a photo, and how the contacts can be drawn in at a later time for others to see.

Also, while walking or driving around, I notice landscapes and outcrops, roadcuts and exposures that tell stories of days gone by, days populated with geologists, pickup trucks, drill rigs, beer, dozers and backhoes, ice chests, map cases, and packs full of this and that, including hand samples, white bags filled with rocks or soils for assay, a water bottle or two, a small lunch, waterproof matches in a ziplock bag, an extra jacket or flannel shirt, a small 1st aid kit, and nowadays a SPOT. These things or places and their stories are harder to photograph, but I nevertheless see them almost everywhere I go.

Examples could be endless.

Things You Find in the Field: Dikes and Drill Holes

2013-04-12T10:00:00.000-07:00

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.

Things You Find in the Field: Roads You Shouldn't Take

2013-04-04T05:00:00.000-07:00

View Bad Road in a larger Map

The road we'll be taking a look at begins at a circular parking area (above and below), and heads up the ridgeline to the right of the drainage centered in the "Bad Road" Google Earth image (above). I haven't attempted this particular road myself, and don't plan on it without walking the mid-slope part of it carefully. Actually, I don't plan on attempting it at all: It looks like a road for "high-markers."

The Prius parked in the circular parking area below the hill climb, which begins just left of the photo.

Having no photos of the beginning of the road, here's a view from Google Earth.

This first part of the road really looks just fine, and there is an almost flat area just over the first rise for turning around.

View of the upper part of the road, which forks.

The main part of the hill climb continues uphill on the right-hand fork, into or through one patch of rocks, and beyond into another. The left-hand fork looks like it's been used to access vehicles that have rolled or slid downhill into the gully.

Closer view of the bad area below, through, and above the rocks.

This part, and maybe the curve just below the fork, looks rather sidehilly from below.

If you happen to make it up this far (into the first set of rocks), don't look back! Instead concentrate on going forward!

Otherwise you might end up in the gully. Vehicle parts are scattered all over.

Interestingly, it appears that Google Earth and Maps captured a vehicle in the process of being dug out. (Click to enlarge, or view here.)

Uphill, the road appears to end in rocks and a series of individual tracks, some of which go back down into the gully.

Instead of this questionable road, I'd recommend taking the switchbacked road that takes off just left of the circular parking area (first photo, with Prius). This road is very rocky in a couple places and requires a high-clearance 4WD vehicle. (We saw a low-clearance vehicle turn around at the first switchback just the other day.) The switchbacked road will take you up to the main ridgeline road, an adventure for another day.

Photos taken in middle and late March during two hikes up the switchbacked road.

Things You Find in the Field: Melted Claim Posts

2013-04-01T09:15:00.000-07:00

Once upon a time in Nevada, 4-inch diameter, perforated or unperforated PVC pipe could be used as claim posts. Prior to some time in the late 1970s or early 1980s, claim posts in Nevada consisted of 4" by 4" by 4' or 5' wooden posts, which even when wormy with holes, were quite heavy to carry on the long claim traverses we sometimes made when staking claims.

By 1993 (possibly as early as 1991) all such PVC posts had to be unperforated and capped to prevent birds from trying to nest in the pipes, then dying when they couldn't get out. In late 2011, removal of PVC posts was mandated in Nevada. Apparently, anyone can pull the old PVC posts out of the ground, but you are required to leave them lying on the ground "immediately adjacent to to the location from which it is removed" (it is otherwise a crime to remove or disturb claim markers and filing papers on public lands).

Most claims in Nevada are now staked with a wooden post "at least 1 1/2 inches by 1 1/2 inches by 4 feet" set 1 foot into the ground. Small posts like these were not allowed in the 1970s and 1980s.

A closer, side view of the melted pipe, showing its originally perforated character.

A brush fire went through this area in July, 2007 (a few photos here). I've seen other melted claim posts from other fires here and there, but this one shows the most extreme melting I've seen so far; the fire must have been relatively hot or slow-moving.

Things You Find in the Field: Metal Bars, Mine Dump, and Adit

2013-03-29T15:33:00.000-07:00

Going up the trail of our old hiking hill in eastern Nevada...

...we'd run right below this old mine dump kind of sprawled across the terrain, with large piñon and juniper trees growing around it and small piñon, sagebrush, and ephedra growing on it. I suspect the trail is partly an old miner's or mule trail put in to access the small mine.

At the base of the dump lie a few pieces of metal.

The metal bars are flat and elongate, with drilled holes at some undefined or irregular spacing. I have no idea what these were used for. At first I thought they had something to do with an old rail-and-cart mining system, but closer examination shows they are too flat to be regular track of any sort.

UPDATE 31Mar2013: The metal bars may be pieces of "strap rail," which would have been attached to wood to create an inexpensive rail system. H/t Guy Starbuck in the comments below; be sure to check out his fine website and blog, Starbuck's Exploring | Exploring historic mine camps and petroglyph sites of the Southwest.

The trail then goes uphill to the side of the dump...

...and peters out into a somewhat slumpy area of soft talus. We usually continue up to the top of the hill from here on a poorly defined trail, but today, let's go examine the top of the dump.

A small opening at the top of the mine dump goes into limestone bedrock.

Let's look a little closer!

Standing on the somewhat caved material at the adit portal, looking inside...

...we see one of those mysterious pieces of metal [see update above] sticking out from limestone debris lying on the sill (what a layman might call the "floor").

Not sure what this writing is all about.

The iron bar points down the adit.

In the back and upper ribs of the adit ("top" and "sides"), a darker, less oxidized limestone can be distinguished from a lower, yellowish orange limestone. This contact would be mappable underground only where it crosses the right rib at waist level, which it might right near the adit portal.

Using the flash of my camera, we can see that the adit continues quite a ways into the hillside.

Now, back on the mine dump, we look south toward Ward Mountain
in the Egan Range.

Looking over the edge, we see the metal bars [strap rail?] at the base of the dump. Shall we go back down?

I don't remember if this was a great boot-skiing dump. I think I went around the side to get back to the bottom.

Three metal bars in the sun.

Closer view: metal bars and ephedra.

Looking back toward the metal bars, we decide to hike back down the hill.

A Mini-Rant about Mine Dumps

2013-03-25T04:50:00.000-07:00

"The briefest description of waste rock dumps is from Western Australia—all you need to know in two pages. [May not be original link; also condensed here to one page.] The most comprehensive description of a waste rock dump is in the EduMine course Design and Operation of Large Waste Dumps. In practice no definition is needed; simply see the picture on the front page of this review."

— Jack Caldwell, from Waste Rock Dumps, rev. 28 June 2006

A mine dump, or waste rock dump, by definition consists of waste rock from a mine — whether it be an underground or surface mine — that has been dumped somewhere, usually quite close to the mine, sometimes even inside a surface or underground mine, so as to minimize motorized or track haulage costs.

Old mine dump.

A heap leach pile (or leach pile or heap) is not a mine dump: the rock consists of ore that is (or was at some time) being processed by some form of leaching. A leach pile sits on a leach pad liner, and can't be moved without placing it on another liner (environmental requirements).

Tailings should not be called mine dumps, either: they are the tails that have come out the back end of the ore processing plant; the heads went in the front end. Tailings (or tails) were once ore, not waste, or they wouldn't have gone into the mill for milling and then processing. They are usually found behind tailings dams (although not always). Tailings shouldn't really contain any ore, but sometimes — perhaps if the mill or recovery plant isn't operating properly or if the ore going into it is of an unexpected or unusual character — some amounts of the ore mineral may get through to form ore-bearing lenses behind the tailings dam. Sometimes — usually in the future when (if) the price has gone up, unless your mill is currently letting through too much unprocessed mineral all the time (therefore right now and also in the future) — the entire tailings mass may comprise a low-grade ore deposit. Many tailings deposits have been sampled or drilled as potential ore. Tails near Kalgoorlie have been mined; Eldorado Gold plans reprocessing of tailings at its Olympias, Greece, project.

Mine dump inside old, inactive open pit.

Many mines stockpile various kinds of ore, often ore that is in an intermediate low-grade category below one cutoff grade and above an absolute minimum cutoff grade. For these "low-grade" stockpiles, the plan is to process them through the mill or on a heap leach pad at some later date, either when (if) the price goes up or toward the end of the mine when many up-front mining and processing costs have been paid off. Sometimes these stockpiles become waste (and therefore become part of a larger mine dump or waste pile) simply because they don't get mined: the price doesn't go up, or end-of-mine costs aren't low enough to make them worth re-hauling, or mining is shut down for whatever reason before the low-grade stockpiles are processed. Other types of ore stockpiles include those made of high-grade ore or some particular type of ore that is recalcitrant to your usual processing. These piles may require special processing or blending with other types or grades of ore.

Mine dump in fog at sunrise.

Waste on mine dumps can become ore at a later date if mining and milling technologies improve or if the price of the commodity of interest goes up. Material on leach pads theoretically becomes non-ore as the metals of interest are leached out, but again, the material is subject to future price and technology changes, and leach pads fail to produce sometimes, leaving the original metals intact or partly intact (it could be argued that the leach piles with unfavorable recovery rates were technically not ore in the first place). I suppose that one could argue that the material on already leached pads is now waste rock, and therefore the old leach pile is a mine dump, but as I mentioned before, the pile is probably on a liner, and it therefore has to be handled differently from any other piles of rock around the now inactive mine.

One could also, perhaps, argue that the tails or tailings are now waste and therefore a mine dump, but I cringe at this idea, because there really is a specific name for that material: tails or tailings. Tails can become ore after their creation if mining technologies improve or if the prices of commodities contained within go up. One hopes that a mill isn't putting too much metal out in the tails; that usually implies a poor recovery rate, and poor recovery rates are usually unfavorable to profitable mining. And mining has to be profitable, or the individual mine owner or individual miner (yes, there are a few), the mining company, or the shareholders of a mining company would be better off putting their money into a bank or a mattress instead of investing in the mine.

Old mine dump.

Most of the mine dumps I see out and about are waste piles and dumps near an old working: a shaft, decline, adit, glory hole, or other old and inactive complex. When I'm working at or near an active mine, I can usually recognize the mine dumps because the haul trucks are actively dumping loads of waste. It can, however, be difficult to look at any given mine and know which piles of rock are currently in the waste or ore category.

I do get tired of hearing every single pile of rock near a mine being called a mine dump.

/rant

Things You Fnd in the Field: Holes in the Ground #1

2013-03-21T04:50:00.000-07:00

While out wandering around here and there in Nevada, and other places throughout the west, you might run across mine dumps and associated various holes in the ground — adits, shafts, declines, and other irregular openings — put in, usually, by old-style prospectors and small or individual miners.

Small irregular opening with small mine dump.

Larger mine dump: Let's go see what's there!

It's a small shaft with old timber as shoring. The round-headed wire nails suggest that this is a relatively recent shaft: probably post-1910.

Openings like this are, nowadays, often blocked off with chain-link fencing or other barricades, which is a fine thing for preventing random people from falling or driving in — often those who happen to be wandering around after dark, or who might be driving across the hills without a good idea of where they are (an old mining district), where they are going (cross country where there isn't a road), or what they are doing (possibly out for so-called fun after a couple beers) — but they make it difficult for people like me to figure out what the oldtimers were digging on, and why, and can prevent sampling the rock, vein, or structure to determine its geochemistry. Barricades can also prevent me from going into accessible adits for sampling and underground geologic mapping, and can prevent or at least hinder other geologists with the know-how and right equipment from going down shafts for sampling and geologic reconnaissance or mapping.

This particular hole was unbarricaded.

Beyond the timber and the rock overhang, the small shaft appears to end only a few feet below the surface, although my photo doesn't show whether an underground drift takes off from the area hidden by the rock at the opening. Enlarging the photo reveals several narrow, parallel white lines across the photo that make it clear that it was raining that day. Enlargement also suggests that a drift does take off from the far side of the shaft, as does the relatively large size of the associated mine dump (second photo).

You always have to ask this question: What were the oldtimers digging on? A few, narrow, high-angle fractures or structures can be seen above the first irregular opening or adit. Iron-staining and possible veining (silica? calcite?) can be seen in the rock at the shaft. Did they mine anything? Hard to say without doing a little more research into the area or more work in the field.

Watch For Rock...

2013-03-18T06:30:00.000-07:00

...Next 9 Miles

Watching!

Still watching!

More hoodoo sentinels, with small arch.

Finally, a place to sit down?

Read a little more about these particular hoodoos here.

Repost: Blackhawk landslide, California - from Pathological Geomorphology

2013-03-15T12:02:00.000-07:00

This article was originally posted at the soon-to-be-defunct Posterous.com site, Pathological Geomorphology, and was transferred here (thanks Kyle!) to the active Pathological Geomorphology (Tumblr). My original post was a response and addition to Callan's Blackhawk landslide post on Posterous, which is now here on the Tumblr site. I've transferred the original photos, added captions, and added a Google Maps location link at the bottom. I've added the original comments (with soon-to-be-dead links to Posterous) at the bottom. Also see this related post here on LFD.

I'm posting a few additional views of the Blackhawk Landslide in California, to emphasize the truly pathological geomorphology of the area. In the views showing slide toe and slide source, I've moved the source area farther into the mountain from the original given by San Diego State [dead (kmz) link originally sourced here]. I've done this based on prior knowledge and published maps. Basically, the entire steep northern face of Blackhawk Mountain is the slide source area.

Google Earth view showing the slide source and slide toe.

Google Earth view looking from above the toe toward the source.

Google Earth view looking from above the source toward the toe.

Additionally, there are other older landslides in the area, most notably the one sometimes called the Silver Reef landslide, which is just east of the Blackhawk. Also, many additional breccias and possible landslide deposits have been mapped in the area. The geologic maps (Big Bear City quad and Cougar Buttes quad) are really awesome, especially if you know how complex the geology really is. There are numerous thrusts from the south, placing brecciated rocks of multiple ages on usually older rocks. In at least one place, bedrock has been pushed over one of the older breccias. Or is it really bedrock?

Back in the 1980's, I mapped a large area of Blackhawk Mountain and surrounding areas at 1inch = 500 feet. I found, and so have others working in the nearby northern slopes of the San Bernardino Mountains, that if you start at the top, clearly in bedrock, sometimes brecciated, and map down, then you will be tempted to map bedrock until you are clearly in landslide debris. If you start from the top and map up, the opposite is likely to happen.

Google Earth aerial view.

Aerial view with annotated geology.

The reason for northward thrusting is the bend in the San Andreas fault, causing the westward, southward side to be pushed northward, breaking over the steepened San Bernardino Mountains in low-angle faults. The thrusts cause brecciation, and the steepening, brecciation, and low-angle faulting predisposes the area to massive sliding. Stratigraphy is somewhat retained in the slides, and gold has been mined from nicely pre-broken landslid rock of the Blackhawk Slide. Silver occurs in somewhat disturbed veins in the Silver Reef Slide.

In the annotated view, the Younger LS deposits (yellow) are Holocene or late Pleistocene; the Older LS deposists (turquoise and pink) are middle or early Pleistocene; the Moderately Old LS deposits (purple and orange) are middle or early Pleistocene; the very old debris flow fan deposit (purple) is middle or early Pleistocene; and the QT Breccias (blue and red) are Pleistocene or Pliocene.

Lockwood DeWitt responded:

Nice! The annotated map/image at the end really help clarify the messyness of interpretation here.

over 2 years agoSilver Fox responded:

And it doesn't even show the really screwed up bedrock!

over 2 years agoKatharine North responded:

Great images, Silver Fox! I'm going back and forth between the annotated image and the non-annotated ones, looking at the landscape differently each time, picking out the details. I like your note about the effect of where you start mapping - good to remember!

over 1 year agoJosiah Gardiner liked this post.

over 1 year agoAndrew Hammonds liked this post.

over 1 year agoEmil Dibble liked this post.

A Geologist who Preferred to be called a Prospector

2013-03-12T05:00:00.000-07:00

In contrast to what I said in a recent aside about prospectors v. geologists, at least one well-known ore finder, John Livermore, preferred to be called a prospector, according to Andy Wallace, his longtime partner at Cordex, and also according to himself (see this oral history).

Exploration geologists who are successful at finding ore deposits are often referred to as ore finders, a distinction I often reserve for those who find more than one ore deposit. I've known several geologists who have made one significant discovery in their lifetimes (so far); some of these geologists have not necessarily, for whatever reason, gone on to find another (so far). Many (several?) of us have found a small to sizable geologic resource or a small ore deposit. (An ore deposit is, by definition, a mineral resource that is economically viable and therefore minable. Some deposits or resources will become economic in the future; some never will be.) Some of us have found ore deposits that then went sub-economic due to changing prices, costs, requirements, or demands; these resources may still be sitting out there waiting to be mined in future (I know of at least one).

According to Andy, many exploration geologists like to think of themselves as prospectors, whereas I usually think of prospectors as the original oldtimer with a burro (a 4WD pickup or jeep these days): a man or woman who is usually non-geology educated, who you find out and about banging around on rocks, crushing chunks of suspected ore to pan for gold, black-lighting in the night for tungsten, always out in the field looking for the next find. Most of the prospectors I've known have been men, but as I've mentioned before, I've known at least two prospecting women (non–geo-types).

Andy also describes a true prospector as having a different mindset from the average exploration geologist. He ends up describing a quality I've also heard referred to as "eternal optimism." An eternal optimist gets up every day sure that today they are going to find "the big one", today they are going to strike it rich: today is the day. This optimism, when I've seen it, is maintained constantly despite all previous indications that maybe today will not only not be the day, but maybe the goal won't be reached at all, the goal being to find that next big ore deposit — find a mine, as we often say. Andy is right in asserting that most exploration geologists do not believe that "over the next hill, they’re going to find the next big one." We do, however, have to maintain hope (or we would have given up on the business a long time ago); but for the most part, we maintain a hope seasoned by a dose of reality. The prospector mindset Andy describes, or the mindset of the eternal optimist as I'm describing it, is a mindset that is sure in face of setbacks. Fact is, the only eternal optimist I've worked closely with did not even see setbacks and was always sure that this current prospect or property would be the one, that this current drill hole only needed to go just a little deeper, or that the next drill hole would strike ore.

As John Livermore has said:

"Something about the prospecting instinct is different from the geological ability. A lot of geologists are not really very good prospectors . They get very interested in the rocks, and sometimes they don't have the one-track mind of finding mineralization. And prospectors, without a college degree, can often be in some ways better than geologists, because they are very persistent, and they get interested in an area, and they'll go over it with a fine-tooth comb."

There may be a difference between what we used to call eternal optimism and what John Livermore exhibited. The eternally optimistic viewpoint we watched in action daily, trip after trip, year after year, was not entirely based in reality. What Livermore went out and did, repeatedly, was turn unknown and unlikely prospects into active mines, and if not into mines, at least into known resources that became mines within his lifetime.

I'm not sure how to spot the difference in the two highly optimistic, highly positive and hopeful outlooks. I do know that the one is grounded in economic reality, the other may not be. Both mindsets have the persistence of the true prospector.

Read more about John Livermore, who died last month, here. Thanks to him for helping to sponsor my thesis and many others.

Jungle Fever, A Documentary about the Bre-X Gold Scam

2013-03-09T04:52:00.000-08:00

Jungle Fever on YouTube

Bre-X: Gold Today, Gone Tomorrow (1st edition, 1Nov1997) is a book I highly recommend reading for the story itself and also for some background into the way things work (or used to work — some things have changed) in the mining/exploration industry. I found that a character list at the beginning of the book would have been useful. The book got into more than one mining scam story, mostly for background about the people involved in Bre-X, and also just as general background about what mining scams are all about (see a list of a few other scams here on page 16). Also read this review of the book by another Nevada explorationist.

I've seen a few would-be scams in my day, but they were fairly minor and easy to spot, and aimed at myself or other grass-roots and early stage explorationists looking for the next best property to pick up, drill, and turn into a mine.

I was out of the business when the Bre-X scandal hit (and when its stock price was going from nearly nothing to its peak in early to mid 1997). The price of gold already wasn't what it had been in the 1980s; it had been sliding gradually for quite some time.

Historical gold price in USD and inflation adjusted gold price in USD,
by Realterm, from Wikimedia Commons.

I went to the Northwest Mining Association meeting in Spokane in December of 1997, thinking to get back into the business after a hiatus of some few years, and found the place in a kind of hectic chaos. Funding for junior mining companies was already starting to dry up, even though the price of gold hadn't quite dropped to its lowest recent low (which it would on 20Jul1999, when it hit just below $253 USD). I had said at the '97 mining convention that if the price ever went below $250, I'd buy (oh well, I'd probably be set for life now!).

Funding for companies and projects bounced back slowly as the price of gold began to rise again into the early 2000s, and after implementation of Canadian National Instrument 43-101 (called "the NI 43-101," "the NI," or "the 43-101"; also see Wikipedia), which — although aimed primarily at properties with economic resources or reserves — became a set of standard procedures to follow for any grass-roots or later-stage exploration property one had even vague hopes of getting promoted to a Canadian or American stock exchange. I'm not sure that getting funding has ever been quite the same since Bre-X, but the 2008 market and commodities crash has also had a negative effect in more recent years.

A Few More References:
Bre-X Strikes It Rich in Indonesia (3Mar1997; with property location map)

The Bre-X Gold Scandal: First there is a gold mountain, then there is no mountain (Andrew Alden's About.com Geology, originally posted 20Apr1997, with later updates)

Bre-X Collapses (19May1997)

Jungle Fever: The Bre-X saga is the greatest gold scam ever. But to understand the enormity of the fraud, you had to be there. Our man in Borneo tells his story (9Jun1997)

The mine, The man, And the scam (probably 1997)

Bre-X Geologist Mike de Guzman Rumoured to be Alive (13Jun2005)

Report: A review of Michael de Guzman's death (24May2007; forensic report dated 17Feb1998)

The mystery of Michael de Guzman (26May2007)

Bre-X Timeline (updated 31Jul2007)

Bre-X Scandal Ends in Acquittal (Oct2007)

Life after Bre-X (31Dec2012; Felderhoff says de Guzman "had nothing to do with it"; probably paywalled)

Five-year Blogger-versary!!

2013-02-28T11:00:00.000-08:00

It was hard to know what date to consider my real 5-year blogiversary. I started blogging in a very limited way on a non-public site back in November of 2006, and continued in that lackadaisical fashion with a second post on the same non-public site in July of 2007. As noted in my first blogiversary post and first Blogger-versary post, I started blogging on that same site in earnest in January of 2008, continuing into February of 2008, with the goal of going public with the blog sometime before the end of that year. Because of the rapid expansion of The Geoblogosphere in late 2007 and early 2008, I made my first post here at LFD on February 28, 2008, and began transferring posts from the now defunct non-public site on February 29, 2008 (Leap Day).

Readership has swelled during the past couple years, with subscriptions to the RSS feed numbering over three hundred.

Individual blog hits have increased gradually over time, though they have never been very high (over 100 in a day is exceptional). Hits declined during the last two months of 2012, but surged back a bit in January.

In any case, I plan to continue blogging as time allows (I've been trying to maintain one or two posts per week during this last, very busy year), and will now go through some of my most used blog tags, with a few accompanying photos.

My blog tag list is huge compared to most blogs (see lower sidebar), and was set up primarily so I could find my posts as easily as possible (i.e., it's my own personal cross-referencing system). Tagging has not been entirely consistent, and I try to correct the inconsistencies whenever I see something, or whenever a category becomes large enough to add a tag retroactively. The number of tags I'm citing below was current on January 1, 2013, when I began this post.

View of the Clan Alpine Mountains, Nevada, from the Fairview Peak fault scarp.

My first largest tag or category is (no surprise here!) Nevada, with 463 tags as of January 1, 2013. My Nevada category includes at least two unfinished series: posts about the Midas area and some Northumberland-related posts including posts relating to The Geographic Center of Nevada. For comparison, the next largest state, country, or province category is california, which came in 13th with 74 posts. Alaska was close behind at 17th, with 67 posts.

Geology is in 2nd place, with 171 tagged posts. I haven't used the tag as often as I could: so many things on this blog could fall under geology, or geoscience in a broader sense, and the tag didn't originally seem that useful to me, especially for my own sense of organization.

Geologic map showing a portion of the Osgood Mountains (map from Hotz and Willden, 1964).

For example, the post from which I took the above geologic map, is not tagged geology (or map!), because I really don't discuss the geology (or the map!). I found the post because I knew it was tagged "work."

Drill rig in eastern Nevada.

The tag in the field comes in third with 163 posts. This is a somewhat inconsistently used tag that includes a variety of overlapping topics. For me, "in the field" often means drilling, sometimes mapping, and sometimes life in the field. It can also mean other things, for example old junk or old buildings found in the field.

Monitor Valley Road, more or less south of The Geographic Center of Nevada.

My variously tagged road posts include those tagged road trip, which comes in fourth at 143 posts. Road trip posts include trips on pavement, including those on interstate highways, and trips on good, fair or middlin', and bad dirt roads. The category includes trips far from home, trips closer to home (or field station location), and trips out in the middle of nowhere (or center of everything, depending on how you view things).

The roadside posts (5th in our countdown) numbered 136 at the beginning of 2013. These posts include what I consider to be my roadside geology category and also include posts about things or places located along the road, always a particular road. Highway 50 has the highest number of overall posts at 108, Highway 8A comes in second at 44, and I-80 comes in third at 20.

Falling rock sign on Highway 89, with Lassen Peak in the background.

An example of a roadside geology post: The dacite of Mount Helen near Lassen Peak on Highway 89, CA.

Another example: Phyllitic slate near Connors Pass, Highway 50, eastern Nevada.

Okay, so the various tags can get a little redundant! The previous picture could be tagged, if pictures were tagged individually, Nevada, Highway 50, rocks, metamorphic rocks, roadside, geology, and possibly a few other things. Highway 50, with its roadside geology posts, reminiscing posts (old times, see below), and roadside attractions posts, comes in 6th overall with a fairly whopping 108 tags through the end of last year. That's largely because I've spent a good deal of time driving that road during the course of the last five years, and spent an even greater time driving that road between the years 1975 and 1991 or so. It's also because I've included in the tag posts for some back roads and highways are within some certain, undefined distance of Highway 50.

Our next category, old times, is 7th with 93 posts.

Posts in this category include those that are entirely about the past, AKA the "good old days," and also include posts about current times wherein I mention how it was in the past or tell some part of an old story.

Old times posts rarely include old photographs; sometimes they include new photographs of old places.

Remains of the old bathing cabin at Spencer Hot Springs (story here).

Somewhat surprisingly (to me, at least), the category volcanic rocks comes in 8th at 80 posts. Well, maybe it's not so surprising: I began my career (after my thesis and after some few short stints at government, government-related, and company jobs) doing exploration in volcanic rocks. Consequently, some of the stories of old happen to be about volcanic rocks or the drilling and exploration thereof, and I somehow just seem to pass by and stop to look at volcanic rocks in my travels here, there, and everywhere.

Tuff of Hoodoo Canyon at the entrance to Northumberland Canyon, central Nevada (from Drilling Stories: Getting Started at Northumberland)

Tuff of Hoodoo Canyon and Northumberland Tuff (more here).

Other types of rocks have been tagged less often at LFD: sedimentary rocks were tagged 74 times by the beginning of 2013; metamorphic rocks were tagged in only 24 posts (although mylonite, a type of metamorphic rock, continues to be one of my favorite rocks); intrusive rocks were tagged 14 times, including one of my favorite of 42 beer posts, Icky with Anorthosite.

The tags mining and winter are tied for 9th place at 81 posts each.

A wintry, mining-related photo from this post.

Exploration, a perennial subject here at LFD, comes in 10th with 79 posts. Exploration can be related to roads, rock hammers and other field tools, geology, geologists, sampling, drilling, mapping, field camps, and helicopters.

Hughes 500-D sitting on an outcrop somewhere west of Beatty, NV, in 1978.

Many exploration posts don't have pictures.

Things You Find in the Field: Another Oasis

2013-02-25T04:55:00.000-08:00

The Oasis at Rye Patch.

A jukebox and "I Want Brew" sign in the corner.

A pool table across the room.

Pull up a chair?

It was a wintry day when MOH and I stopped by The Oasis sometime late last year. We sat at the bar, had a burger or some such, and an Alaskan Amber. I was surprised to find anything but the Bud, Bud Light, Coors, Coors Light, or (if you're lucky) MGD that are prevalent in small bars across Nevada—but good brews are becoming more popular in the outback and are, hence, more available.

The Oasis at Rye Patch is a cozy place, overall, with a nice sign out front (see this) and good pizza inside. I recommend the pizza from a dining experience or two back in 2004, when I was working in the area for a now defunct company that was running one of the nearby mines (the mine is still running).

Things You Find in the Field: An Oasis

2013-02-22T05:00:00.000-08:00

The Oasis in Niption, CA.

It's a decent place to get a burger, drink iced tea, hang out, and play pool.

Pool cues.

The Oasis is surrounded by trees, and has lots of historic and informational photos on the wall. We thought about staying the night, but accommodations weren't available on zero notice, so we went on to Needles (fondly known as Needless). When leaving, we had to wait for a train to pass.