CR Briggs Gold Mine

The CR Briggs Gold mine is located in Death Valley, California. They are mining a gold ore which contains .001-.02 oz./ton of metal. Industry standards and the current price of gold dictate whether this is worth mining. The ore is a sulfide type, which means that there isn't free or native gold in the rock, instead it is locked away in sulfide minerals like pyrite. It is found here because a fault that originated due to the extension of California away from the American plate provided a pathway for gold-bearing fluids to come up. A cyanide leaching process is used to remove the gold from the sulfide minerals.

Overlooking the open pit gold mine. Our guide, William Stanley describes exactly what is going on. The trucks constantly run from the crusher, tailings pile and the bottom of the pit. The dump trucks get directed after they get filled, if they are full of good gold-bearing ore, they go to the crusher. If not, they go to a tailings pile which is saved to fill back in the pit after they are done working. Because there is so much activity, we could only watch from the top at this point. 

Soon enough, a loud buzzer was heard and the pit was cleared for us to drive to the bottom and see the ores.

The two drill rigs to the right side of the picture are there to drill holes for explosives. About every two to three days they blast these explosives, exposing more ore, and making the pit deeper.  Interestingly enough, they had to take into consideration their dust from the blast and how it might affect migrating birds when proposing their operation to the EPA.

Geologist John Kinney stands next to a vein of rich ore down at the bottom of the pit.

Our Suburbans were hardly as high as the tires on these dump trucks. Our guide told us that these were even the smaller variety of trucks, and that the larger kind could fit this dump truck into its bed. They take the gold ore to the crusher, which makes it all into .25" or smaller. This crushed rock is placed onto the leach pad, where sprinklers and drip lines that distribute the cyanide solution keep the heap producing gold.

This is the water that comes out of the Cyanide heap. It is rich in both cyanide which is now bonded with gold molecules. The netting sits over the water to prevent wildlife from accessing the water. As you can imagine, water is rare in Death Valley and so they have quite the variety of wildlife that attempts to get in. Every so often they get tasked with saving a bird from being stuck underneath the netting.

This water is treated by this small building, wrapped in extra barbed wire and secured with several cameras. They bring the water up through activated carbon filters, which precipitate the gold out. This gold is then taken from the carbon using acids and re-precipitated out to produce an ingot of gold and silver. They don't bother to separate the two, they just sell the whole ingot to the refinery. The cyanide leach pit will continue to produce gold for up to 10 or 15 years after the actual mining of material has ceased.

Death Valley Spring Break 2012

 This is what you find when you walk around in the lowest place in the United States (-282 feet):

It's salt. And there's a lot of it in Death Valley. Sometimes it is borax as well, which they mined in these parts back in the day. This particular place is called Badwater. There's not much here, just a parking lot, some stairs that lead down to the salt flats, and a green sign with white lettering perched high up in the mountains aside denoting sea level.

 So why were we in Badwater, CA? On a geology field trip.
Why am I doing a handstand in the lowest place in North America? Why not.

Looking South back upon Death Valley, Furnace Creek is almost visible in the left center of the picture. The valley here is very wide, and dunes have formed from sand blowing down the center.

Here, a fault scarp can be seen. This scarp is most likely from one magnitude 7.0 earthquake.

 We drove from Colorado to California to look at fault scarps, and map them. A fault scarp is a steep change in elevation left behind by an earthquake. Death Valley is a interesting place given the topic; active field tectonics. The tectonic activity of earthquakes in CA and the severe lack of precipitation in Death Valley have produced a unique environment where the fault scarps are well preserved and plentiful.

 This is a perfect example of what is called a megabreccia. They form when grinding action of a fault is so strong that the rocks shatter. It also means that the rocks were not at a very high temperature or pressure when they fractured, which makes it hard to explain why they build up so much energy. Most breccias have clasts on the order of pebbles, and a large breccia may have a cobble sized clast. These clasts are the size of volkswagon beetles, and cemented in with a solid cast of calcite. This wall is in the lower stretches of Titus Canyon, a small one-way 4wd road through a beautiful and sometimes forboding narrow canyon.

Looking South from Furnace Creek to the Panamint range, you can see snow on Telescope peak at ~11,000 feet.

Normal faults could be found in the lake sediments, high angle extensional fractures as seen here. Pike, my mapping partner, is for scale and is standing on the hanging wall.

This is a view of the gold mine, which will have to be another post all of its own.

Conglomerate; these were all once rocks that you may see in a river, but have been stretched into cigar shapes due to tectonic stresses.

A large drainage was diverted into a much smaller drainage to save a hotel from seasonal floods that contained a lot of alluvium. In just 50 years, this drainage has been formed, incising ~30 feet.

 Darwin Falls, the last thing you would expect to find in Death Valley

Scorpion Lollipop, and some turquoise found along the way.

Joshua Trees

Sand dunes in the Saline valley. You can see that the alluvial fans are a rough surface. They are covered with cactus and some brush. The scale here is huge though, because the cactus in the foreground may only be about a foot tall, the line of dots below the dunes are cars, about two miles away, and the dunes themselves are approximately another mile from there.

Scours in sedimentary rocks

Scours are sometimes visible in sedimentary rocks, and if you could identify one it allows you to conclude a few things from looking at an outcrop. The most important thing that you can figure out with a scour is which direction the water was flowing as it was created.

These marks in sedimentary rocks are created when the flow of water is suddenly increasing. Mudstone (or sandstone just relatively softer)  is deposited when there is little flow of water, and the the clay particles have time to settle to the bottom. As water speed picks up, the flow can knock pebbles onto this muddy surface.

Directly behind the pebbles that lie on the mud surface, a small suction is created where the water picks up higher speeds as it travels around the pebble. This faster moving water in turn begins to erode away the mud behind the pebble. More pebbles tend to fall in these eroding holes, speeding up the process and resulting in a common indicator of scours, the coarse infill. Knowing that the mudstone is below the coarse infill, you can determine stratigraphic up, or which way was vertical when the rocks were deposited and before they were uplifted.

Scours make a very typical shape that allows you to determine the flow direction of the water. On the upstream edge of the scour, the contact between mudstone and infill will be very steep, almost vertical. On the downstream edge, the slope is gentle into the trough. Using this information, you can determine which way the water was flowing, which can provide interesting insight about the history of the rock.

North Table Mesa Zeolite Crystals

Looking across Clear Creek Valley to South Table Mesa from one outcrop of amygdalar basalt.

Zeolites are microporous minerals formed from aluminum and silica. Microporous means that their mineral structure has large holes in it, and this feature gives way to the usefulness of zeolites.  They can be used to purify water by the means of ion exchange beds that consist of zeolite minerals. For the same reasons they are commonly used in laundry detergents.

Although the zeolites found on Table Mesa aren't useful for purifying water, they are quite spectacular in their occurrence. The delicate and intricate zeolites from this locality are prized rare specimens that rarely occur together in other parts of the world.

They are found in the amygdalar basalts in this locality. Amygdalar simply means that there were holes (or vesicules) in the rock that have been filled in by some material, which is usually calcite or zeolites. If there were no material in the holes, it would be simply a vesicular basalt. The zeolites are reported occur in seven different varieties, but the most common seem to be thompsonite, analcite, chabazite, okenite and mesolite.

A cavity of thomsonite (the tan balls) that has been opened and exposed to weathering.

The basalts of Table Mesa are very difficult to break up. Attempting to break these rocks with a 16 or 22 oz. rock hammer would be rather futile, and its doubtful that your hammer would weigh the same after so much steel would get taken off.  Even my chisels would show a new imprint of the sledge's face after each impact, and the top of the chisel would mushroom out a bit and curl back with each hit. Usually, after smashing at a face for a few minutes with the sledge and chisel, you will get a fracture in the rock.

After a fracture has been propagated, which usually tends to be along the long axis of the zeolite pockets, you have to go and break out the ends of the fractures so that the rocks can be removed. Otherwise, they all fit in just like puzzle pieces that despite being loose do not want to be removed. After demolishing the rock to removable pieces, you get the pure pleasure of removing each piece and inspecting it for crystal-filled pockets.

This amygdule contains analcite, chabazite and thomsonite.

Sometimes you get nothing, and sometimes there are some large cavities. One indicator of finding pockets seems to be oxidation of the rock immediately surrounding the pocket. These little trails of oxidation can lead your hammer from one pocket to the next.

I believe this to be an okenite crystal (~2.5 cm) among chabazite (square white and clear crystals), this specimen (in-situ) was destroyed in the attempt to retrieve.

The zeolites are somewhat zoned, and in some areas different types of zeolites will be found more frequently. For example one area was characterized by large cavities of purely thomsonite. Other areas had cavities filled with thomsonite and analcite, and some contained purely chabazite. The amygdules in the thompsonitic area were commonly 6" long and 2-3" in height and tending to be stretched in a NW/SE direction. The largest was over a foot long and about six inches tall, with two separate cavities attached. It had however been broken out a long time ago and was therefore quite weathered.

Chabazite crystal showing its pseudo-cubic structure.

Also of note was the immediate change of color when the minerals are brought out of pocket. Within five minutes of exposure to air, my translucent green thomsonites had dulled to a tan coating outside. The more weathered thomsonites are completely tan. Also the chabazites, which in their cubic form resemble NaCl or salt crystals, are clear and transparent when first broken out but quickly gain a slightly white coating on the crystal after exposure.

An analcite crystal with thomsonite on basalt matrix,  the analcime is quite large for this locality(~1.5 cm wide)

Although a lot of effort oft results in cracked and damaged crystals, there is a technique to collecting these crystals from the pockets. A hard day's work may result in only one or two nice specimens, and sometimes the best ones escape you. If you decide to head up to Table Mesa, be sure to check that collecting is allowed before you go. Bring along some soft packaging to transport your crystals back to the car, because the jolting of carrying them can also damage the crystals.

Bailey Creek

I just stumbled across this picture from summer '11 on Bailey Creek, southwest of Denver, CO.  Its a beautiful and continuous class V kayak run through a remote canyon. Towards the end of the run, the canyon flows through a granitic wonderland, with huge (200' wide) boulders scattered in the river channel to create small rapids. While the beginning of the run is definitely all Colorado boating, with tight, steep canyons and quick moves to be made, the granites at the end of the run inspire thoughts of Cali boating.

I'm in the white Jefe in the front center of the picture. My cousin, Ricky Hoberg is performing the move that I had just failed to do, and as a result, am facing upstream. The desired move is to slide off the dry side of the rock back into the current. Otherwise, you get pushed against the rock sticking out of the water just to the left of my bow, which can cause problems.

Just out of view in the bottom of the picture is a large hole, which by the time I had gotten my boat turned back around was right below my feet. The plunge was considerable, probably 6', and I had rolled into it without any forward speed. As my boat slipped over the edge and into the white foam below, I knew I was in trouble. I plunged vertically into the hole below, going so deep that almost my entire boat was submerged before returning to the surface upside-down. After waiting to be flushed from the hole, which didn't take long, I had to try and roll my boat back right-side up, which took about three or four exhausting and breathless attempts.

 On the edge of the river below, when you look upstream to what you have just run, that is the sweetest part. The steepness is apparent when looking back upstream. The adrenaline was flowing and the sun was shining. I don't think that I will ever forget that run.

Barbour Ponds Ice Fishing

On a pleasant friday afternoon, my friend Hamric and I headed to St. Vrain State Park, where the Barbour ponds are located. There are lots of ponds here that hold good fish and good ice for a portion of the year. This was my first time using my own ice fishing gear, including a homemade ice fishing pole, and also using my old auger with new blades.

I pulled my Dad's old hand auger from out of a pile of junk in the shed. My Mom, sister, and myself had probably given it to him as a Christmas gift some years ago. It had been well used until its replacement, the two stroke auger came along. The blades on it were so rusty that they would hardly even scratch the ice. It would have taken hours of effort to bore a hole with those blades that you probably would have had better luck with a pocketknife.

It is tough to recall which ones are old and which ones are new

But for $35 they sell the replacement blades, which can bore a hole like a squirrel on crack going after a peanut butter jar.  While I was buying the blades, I spent a few more dollars on the ice ladle that pulls out all of the chunks remaining from the auger, which is worth it in the long run.

After paying the $7 entrance fee, the attendant informed us that "sandpiper" was fished out, but there were people catching fish on "coot", "mallard", and "bald eagle". The ice was about 4-6", and generally safe.  We drove to mallard and got our gear/beer out on the ice.

Typical Ice Fishing jigs, with quarter for scale.

After being very impressed with the augers first drilling performance, I set up with a small jig with a 1/2 mealworm and splitshot, the typical ice fishing set up. I found the pond to only be around 5' deep. At its deepest we could estimate that it was only around 10' deep.

About 30 seconds after I had dropped my line in, and while I was helping Hamric set up his line, I saw my line run sideways out of the corner of my eye.  When your line moves in the hole, you know that a fish is playing with it down below. I cautiously picked up my rod, and gave it a small tug back. BAM! The fish set, and I pulled it out of the hole. Altogether, I'd had about three feet of line out.

It was a 12" stocked rainbow trout, not more than a minute after having put a lure in the water.

We fished Coot lake and Mallard lake catching lots of fish at each lake. The stocked trout there are hungry. The park ranger who checked our licenses told us that earlier in the year some ice fishers were pulling out 2-300 of these trout per day. Now that would be fun!

Hamric anticipating the next bite.

We caught 8 fish in the few short hours that we were there, and kept seven for a fish fry.

Even thought they were stockers, they still tasted good in trout tacos! The largest we caught was around 15" long.

My next investment into ice fishing will be some cleats. While it isn't too bad slipping around on the ice at first, after just a few hours it becomes annoying. Falling on the ice is painful as I have experienced. Right when you walk away from your pole, which could be after a half hour of sitting with no bites, you look back and the tip of your pole is wiggling. The line is swinging from side to side but you are five feet away. It is impossible to walk, you must dash headlong toward the pole before the fish gets away with your mealworm. But always your feet travel faster than your body without friction against the ice, and you come crashing down on your back knocked windless to lie and watch your line lie still in the water, the fish leaving the hook empty. Long story short, I think i'll make the small investment for some cleats.

All in all, Barbour Ponds in Longmont, CO has some good ice fishing. We were able to take home a nice stringer of fish for dinner and have fun doing it. For the price of $7 and some gas to make the drive from Boulder, it is some decent fishing!

DIY Ice Fishing Pole

After going ice fishing with my Dad, I had seen that some of his poles had been glued together. He explained that these were his broken poles from over the years, salvaged for ice fishing. Hearing this made me think of my broken pole that I was sure I had thrown into the trash.

This fall, I loaned one of my cheap fishing poles to my cousin for a halloween costume. Not too suprisingly, when the pole was returned the lower half had been cracked as to not be cast-able anymore. The cork handle and top of the pole were still intact and entirely functional. I assumed that I had thrown it away, but as I was cleaning my house one day, I lifted a couch and VOILA!

My new ice fishing pole.

It was incredibly easy to make the conversion, I used a few common tools and writing this article has taken longer and required more thinking than making the pole!

What I used:

Adhesive (superglue)
Hacksaw (with masonry blade, but any saw should do the job)
Sandpaper - 250 grit aluminum carbide
Time

Taking the hacksaw, I cut the pole about 4" above the cork grip. I didn't want to cut it too short the first time, and I think it should be more stable with a few inches of overlap between the poles. My Dad's poles were cut right above the cork grip, so anything in between should work as well.

The cut left some nasty little metal and graphite things sticking out that were too sharp and dangerous. The sandpaper smoothed these out quickly.

I put adhesive inside the handle, where the upper pole would go. The upper pole fit inside the handle with about 2mm of extra space around it, just perfect to be filled with adhesive. I put as much adhesive as I could inside, and pushed the upper pole in until it fit snugly against one of the bulging wrappers for an eyelet.

I made sure to align the eyes to the correct position with respect to where the reel would go, and set it aside to cure.

Step into the freezer...

Basal ice from the GISP-2 core. This ice was the second to last meter before hitting bedrock, where sediment has been pulled up into the ice by the flow of the ice

      I spent most of my hours for the latter half of the summer at the National Ice Core Lab, where the current project was processing a 3.3 km long ice core that comes from Antarctica. That was about all that I knew going into the job. Later on, mostly through talking with the PI's and graduate students, I learned that there is much more to this than meets the eye. There have been more than 20 years worth of planning and work that went into this particular ice core.  The concept for a core from Antarctica was first conceived in 1989, when scientists were working on processing GISP-2, an ice core drilled from Greenland. Their work inspired curiosity to see if ice from the other side of the world would show them the same things that they had seen in GISP-2.

Ice Cores drilled over twenty years ago reside here at NICL in a -46 C deep freeze

As the cores are brought out of their tubes, they are measured and aligned according to how they were marked
in the field.

     These scientists, such as Kendrick Taylor and Mark Twickler, spent years obtaining radar profiles, mapping the bedrock below the ice, and looking at the rates of flow in the ice. When influenced by gravity, ice behaves fluidly, and actually flows. The motion is described in introductory geology texts as being similar to dropping pancake batter onto a hot skillet, where it pools and gains elevation where locally applied, but quickly flows outward. The data that the scientists are seeking would best be obtained from an undisturbed section, where they can be confident that mixing or motion of the ice is relatively low. After several years of research, they found a spot in the West Antarctic Ice Sheet, along a divide where the elevation was highest. The ice was thick there, and the bedrock profile showed that there was a large valley surrounded by two distinct and sharply rising mountains on either side. The hope is that in a dome or a divide, the motion of the ice will be low in the center of the feature. As they began test drilling to measure accumulation rates, the site took on its acronym, WAIS Divide.

The Horizontal Saw, also known as the H-saw, cuts two slabs of thicknesses 1.3 cm and 3 cm

     It is important to note here that the science of drilling deep ice cores was relatively untested, if not new,  at the point of conception. During the twenty years of planning to drill this ice core, they had to design and drill their own new drill, invent new instruments to measure the ice, and figure out schematics of living in the harsh ice covered land. They even went to such lengths as to figure out whether or not they could leave their human waste on-site (as it turns out they did, and they have figured that the waste pits will be stretched into a 1cm layer and pulled out to sea). Labs like NICL were constructed to store and process the ice cores that were being drilled from Greenland and Antarctica. The only other time that the U.S. had drilled for ice in Antarctica was at Byrd, a site that was selected because the numbers of its latitude and longitude sounded "nice", and without any consideration to radar profiles or disturbance of the ice. What they came to conclude after drilling and analyzing a core from that site is that folding and mixing near the bottom of the ice had stripped the core of its ability to represent correctly the ancient stratrigraphy, and thus held little scientific value.

   After they had worked out every detail of the drilling, they set out to antarctica for their first field season in 2006. They were only allowed one snow-cat to work with to construct all of their drill shelters and work areas. Drillers who were on the job for all season had quarters, visiting scientists resided in a field of tents specifically designed for the Antarctic. For five seasons of work in the field, they have 3,334 meters of ice core to show for their hard work. That's a hole that descends 3.334 km into the ice sheet. The amazing thing is that the drill only takes 3m of core at a time, and they have to pull up and lower the drill head into the hole each time. The wait times to winch the drill in and out while nearing the bottom of the hole were nearing 12 hours if I recall correctly. They stopped their drilling for fear of what is at the bottom, and for concern for the environment. There is a strong belief that at the bottom, near the contact with bedrock, the ice begins to melt, and sits upon a large body of water. If the drill penetrates the body of water, the drill fluid ( some nasty chemical) will be released into the otherwise untouched body. To keep the borehole open while drilling, they had to pour in some 200 barrels of drill fluid.

     The drilling teams only work during the North American winter, when it is warmest in Antarctica. Weather permits them a relatively short working season, because an ice breaker ship must be able to reach Mc Murdo, which acts a supply point for this camp and others on Antarctica.

The "ECM" or Electrical Conductivity Meter Sends an A/C
and D/C shock through the ice and measures the result

The resulting readout from the ECM

And so, after all of this effort, someone has to be able to use the ice to do some science. Every week at NICL, we would have a scientist give a talk. Usually it was a PI who came to visit, but scientists who were staying the whole summer also gave their talks. There are over nine PI's, or primary investagators that collect samples and run them to receive the data, which is in some cases then handed to another scientist for analysis. Scientists use machines that often times they have built, with complex functions and names like mass spectrometer and accelerated particle spectrometers. They look at a wide variety of things in the ice, including gases, chemistry, isotopes, physical properties, its electrical conductivity, and there is even someone who counts each and every visible layer within the ice. The level of analysis on the core is amazing, we heard from Kees Welton who looks at Beryllium-10 isotopes within the ice as indicating the amount of incoming solar radiation per year of accumulation. His data is correlating quite nicely with known sunspot counts that were visually confirmed and marked in history over the last few thousand years. Scientists used data from Greenland ice cores, other sites in Antarctica, and other outside data, and have proved the existence of several correlations. Most of the data that they analyze comes in the form of squiggly little lines that represent annual or event-based changes, much like the data from the ECM.


   The ice at the bottom of the core was estimated to be around 40,000 years old. This estimation is made from a proposed depth-age scale and from the actual count of the annual layers. One day, we took "snow" from the planer, a machine used to flatten one half of the ice core, and made some snow cones with grenadine and strawberry syrup. We chose the planer because it cuts from mostly the interior of the core where the exposure to the nasty drill fluid is least. I could never have imagined that a 40k year old snow cone could taste so good on a hot day.

The first cut of the chemistry slab is made on an ice core from over 3 km below the surface


The work that I did involved taking a 3 cm thick slab of ice, roughly a meter long and about 12 cm wide, and cutting out of this a 3 cm tall by 3 cm wide stick of ice. This stick of ice roughly a meter long would be shipped to Nevada to be processed with what is called a "continuous melter". This produces a constant flow of meltwater that can be tested as it is melted. By running this melt through several machines that measure different molecules, a large amount of information is obtained from these samples. During cutting, the bandsaws produce "snow" as if they would produce sawdust if cutting wood. This snow must be removed from the samples using a paint brush. This stick then had to be bagged, labeled, and its card correctly stapled onto it in order to be put into a box, which was put onto a pallet to be shipped to the PI. The remaining pieces also had to be bagged and sent to the pack-up station, which returned the remaining pieces of the ice core to the tube in which it came and stores them in the deep-freeze, for the possibility of future research. During the whole process, plastic gloves must be worn to prevent contamination of the core.