Spooky Speleothems for a Saturday Scarefest

To be perfectly honest, I really detest the part of a cave tour when some teenaged guide who knows nothing of the geology goes on and on about how a particular cave decoration (speleothem) looks like a dragon or a elephant or whatever. On the other hand, the human mind has a great capacity for constructing forms and patterns out of totally random scenes. So, in honor of All Hallow's Eve I offer a picture I snapped in Lewis and Clark Caverns in Montana. I don't know about you, but I see at least one scary looking ghost and a cackling witch. What do y'all see?

Watch out for that candy coma tonight, and don't run over any trick or treaters!

Hosing Down the Mother Lode: Hydraulic Mining

Continuing our journey through the Sierra Nevada Mother Lode on our field studies trip last weekend, we arrived at Chili Gulch south of the town of Mokelumne Hill to talk about another way of wresting gold from the earth. We were gathering at a rather poor roadcut when a local rancher drove up and offered to let us onto his property where the walls of an old hydraulic mine could be seen. I was thrilled (ranchers don't always like geologists, as many of you know). The picture above shows some of the Tertiary "Auriferous" Gravels exposed in the old quarry wall. These gravels were obviously carried and deposited by a vigorous river, but at this point we were several thousand feet above the present-day Mokelumne River. How did river gravels end up near the top of a mountain??

The trick is to realize how much the topography of the Sierra Nevada has changed in 50 million years. If one were able to travel back to that era, a flight over the Mother Lode would have revealed a shoreline where the Central Valley is today. The shoreline would merge into swampy estuaries and lagoons, and every so few miles along the coast a large river would be flowing into the sea. Looking eastward would reveal a surprise: where the present Sierra Nevada Crest pierces the skyline there would be...no mountains! They had not yet risen (I hereby acknowledge that there is some fierce debate about the uplift history of the Sierra). Instead, the rivers would be flowing from sourcelands in central Nevada, or maybe even farther north and east (one has to wonder where the diamonds came from). The path of the rivers through the Sierra is fairly well established, and becomes more speculative as one travels farther east (see the map below).

Ash eruptions and lava flows covered parts of the Sierra Nevada while the mountains were rising, and rivers were diverted to their present-day channels. The rivers carved deep canyons as the mountains rose, isolating the patches of older stream gravels on the adjacent ridge tops.

It didn't take the forty-niners long to dig up and process all the gold-bearing gravels in the present-day rivers of the Mother Lode: they were pretty well played out by 1853. Some enterprising (i.e. hungry) miners started exploring the slopes and mountains above and soon found the Tertiary River Gravels, but there was a problem: they needed water to sift through the gold-bearing sediment, and water was not abundant on the mountain ridges.

It did not take the miners very long to come up with an ingenious and devastating solution to their problem. They built reservoirs in the high country near the Sierra Crest, and diverted the water before it flowed into the deep canyons. Using literally thousands of miles of flumes, canals and penstocks, they delivered water to the mines on the mountain tops, and using giant nozzles (called monitors) they blasted the cliff with stream of high pressure water (photo below). They had (re)invented hydraulic mining, one of the most destructive human activities to ever affect the Sierra Nevada and adjacent Central Valley.

To capture the gold, large riffles were carved in the rock where the water left the mine quarry. Hundreds of pounds of mercury sat in the riffles to amalgamate the gold, although the sheer quantity of water swept much of the mercury (and plenty of gold) downstream. Of course, ALL of the loosened debris was sent downstream as well, and there was a LOT of it. What was left behind was widespread devastation.

The hydraulic pits were cleared of all topsoil, and many square miles of forest were washed away, sometimes to a depth of several hundred feet (the original surface of the mine shown above coincided with the gray ledge on the far ridge). In a few places, like Malakoff Diggings State Park, the old quarries have taken on a vaguely Bryce Canyon-type beauty, but that is the exception.

Downstream, sediment choked river channels many tens of feet deep. In the picture below, the full thickness of the tailings can be seen in the terrace at the top of the photo. The stumps in the channel are actually the fifty foot level of mature trees that were buried in the gravel. The mud and silt continued downstream to fill the shallow channels of rivers in the Central Valley. Flooding became a yearly problem in towns like Yuba City and Marysville. About 40% of San Francisco Bay filled with mud from the mining operations. The total amount of sediment (1.5 billion cubic yards) was eight times what was moved to dig the Panama Canal.

The devastation of the mining finally drove the victims to court, and in 1884 the Sawyer Decision declared that the hydraulic mines had to confine the waste sediments to the mine property. The ruling effectively ended large-scale hydraulic operations in the Sierra, but the not pollution problems. Mercury continues to contaminate the mine properties, the sediments downstream, and San Francisco Bay. At some of the worst mine sites, an ounce of mercury could be panned out of two pounds of sediment.

As an aside, a few years I was watching the movie "Pale Rider", the Clint Eastwood western. It was set in the Gold Rush era Sierra, and the good guys were the gentle placer miners, who with their gentle and beautiful wives and children gently pulled gold from the little streams near their village. The bad guys of course were hydraulic miners who wanted to destroy the bucolic little town. The pictures of the hydraulic mines were well done, and there was, as I recall, a mention of the Sawyer Decision that ended the mining. They solved all the problems at the end of the movie by shooting at each other, of course.

Cave Bacon and Stalactites on Drugs: The Mother Lode Underground

During our field trip outdoors last weekend, we spent a lot of time underground. One of our stops included a tour of Black Chasm Cavern near the town of Volcano in the Mother Lode of the Sierra Nevada. It is a strikingly beautiful cave in a region that is not really known for its cave systems, but they are there and they are a truly unique place to learn about geological processes in the Sierra Nevada.

Most people, if they ever think of it all, will associate the Sierra Nevada with granite, an igneous rock that forms from the slow cooling of magma miles beneath the surface. As a point of fact, only about three-quarters of the Sierra is composed of granitic rocks, and only a small percentage of that is technically granite (mostly it is granodiorite). The remainder of the range is covered by volcanic rocks, or is composed of older metamorphic rocks, including a significant amount of marble. Marble is derived from the heating and deformation of limestone, which formed on the floors of Mesozoic and Paleozoic tropical seas, possibly as coral reefs or carbonate shelf deposits. The rocks were lifted from the ocean floor and added to the edge of the North American continent when the terranes collided with the Cordilleran subduction zone in Mesozoic time.

Marble, like the limestone from which it was derived, is composed of the mineral calcite. Weak acids in the soil and groundwater react with the calcite, carrying it away in solution, forming the openings that eventually become the caverns. As the Sierra Nevada rose and deep canyons were eroded across the range, the groundwater table dropped, exposing the caverns to the atmosphere. Water dripping or seeping into the cavern evaporates, leaving behind the mineral deposits that hang from the ceiling of the cave or rise from the floor (dripstone deposits), or which cover the walls of the cave (flowstone deposits). Collectively these cave decorations are called speleothems.

More than 1,000 caverns grace the Sierra Nevada foothills. Some of the caves are world-class in their intricacy and decoration. One cave in Kings Canyon National Park has more than 2o miles of passageways. Many of the caves are also extremely dangerous: most are developed in vertical passageways with deep unexpected dropoffs, and these serve as sinks for "bad" air (carbon dioxide is a heavier gas). On the other hand, some of the very nice caves are open for guided tours: Crystal Cave in Sequoia National Park, Boyden Cave near Kings Canyon, Moaning Cave north of Columbia, Mercer Cavern at Murphys, California Cavern up the hill from San Andreas, and Black Chasm, site of our exploration last week. A trail near New Melones Reservoir leads to the Natural Bridges, where Coyote Creek flows through a cavern.

Black Chasm is named for the deep cleft not far from the cavern entrance that drops 90 feet or so into a small lake. The lake extends at least another 60 feet downwards into the mountain. The chasm prevented the miners and other early explorers from exploring (and vandalizing) the more remote passages of the cave. As a consequence, the owners were able to develop the cave with a mind towards preserving the most pristine parts of the cave. They constructed stairwells and pathways across the chasm, with handrails preventing visitors from accessing and breaking the most fragile speleothems. The cave was opened for tours about 2001, and it quickly became my favorite choice for our geology field trips.

Besides the well-placed lighting system that highlights some beautiful draperies (cave bacon) and stalactites (see the second picture), the cavern offers some of the best developed helictites to be found anywhere (top picture). Helictites are essentially stalactites that have forgotten to follow the law of gravity. The precise details of the their origin are enigmatic, but water pressure clearly plays a greater role than gravity does. They are exceedingly fragile and are usually the first things to be vandalized in unprotected caves. Black Chasm has a spectacular wall covered with them (my photo is of a small corner of the entire panel).

The operators of Black Chasm offer a group discount, and the guides enjoy speaking to geology groups when they get the opportunity. It is well worth a visit!

If you are interested in exploring wild caves, preservation and protection is the highest priority. As such, you should get in touch with the local grotto of the National Speleological Society if you want to be involved in protecting this special resource. If you have followed my blog for any period of time, you will know that I think that cave vandals are one of the lowest and most moronic forms of humanity in existence.

A Geology Professor Passes: Donald B. McIntyre

I've received word from Dr. Eric Grosfils at Pomona College that one of the professors from my days at Pomona has passed away. Dr. McIntyre was a truly unique teacher, challenging, sometimes frustrating, but an excellent professor. I look back and I realize I was not as ready for college as I thought I was when I arrived at Pomona in 1977. I had transferred from the local community college, and though I had done well enough, I was now entering one of the most highly regarded and challenging geology programs in the state. I felt like a fish out of water!

Dr. McIntyre taught a class on Global Tectonics. I thought was going to be told about divergent and convergent boundaries and evidence for continental drift and other basic "stuff". Instead, we were given the keys to the library, and a list of the original classic papers in plate tectonics to study so we could learn for ourselves not the basic facts, but what the original evidence was, what the detractors and opponents had to say, as a preparation to analyze the arguments in class. As a student in Dr. McIntyre's class, I had become, in essence, one of the researchers fighting the academic battles of the late sixties and early seventies. It was uncomfortable for me at the time, and yet a valuable life-changing lesson. Science isn't facts. Science is a process, a sometimes difficult process for gaining knowledge.

Dr. McIntyre could be almost imperious at times, and calling him "Donald" could earn a person a cold stare and silence. Yet most times, he was a warm and friendly person. He and his wife hosted a Christmas party for the students in the department every year I was there. It was a nice gesture for students who were sometimes several states or entire oceans away from their homes. I can remember him pulling a volume off the wall of his personal library to show me a passage on the history of mountain climbing in Scotland. The author had said that his climbing partner, one Donald McIntyre, if he ever fell off a cliff, would be licking the rocks on the way down to better identify them!

I worked in the department at Pomona for a couple of years while I decided the next step in my own educational journey. Serving as a laboratory and field assistant to Dr. McIntyre and the other professors at the school was as good an education as anything I ever learned in a classroom. I moved on in 1982. Dr. McIntyre retired and moved home to Scotland in 1989, and I occasionally heard of his activities through the school alumni announcements.

I finally was able to journey to Scotland in 2001, and my students and I were able to share a meal with Dr. McIntyre in Inverness. It was a wonderful evening. He was, as always, a gracious and polite conversationalist. It was good to see him again.

These are some of my personal remembrances of working with Dr. McIntyre. I invite you to see a bit more of his lifetime accomplishments at his website. He will be missed. The announcement from Pomona College follows:

Donald B. McIntyre, Professor Emeritus of Geology, died on October 21st in Scotland, where he had lived since retiring from the College in 1989. He was 86 years old.

A memorial service will be held on Friday, October 30, at 11:00 a.m. in St. John's Kirk, Perth, Scotland.

A native of Edinburgh, Professor McIntyre received B.Sc., Ph.D., and D.Sc. degrees from the University of Edinburgh and taught there before joining the Pomona faculty as an associate professor in 1954. The following year he succeeded A. O. Woodford as Department of Geology chair, a position he held for almost three decades. Professor McIntyre's research interests were diverse, and his achievements earned him numerous honors, among them Fulbright and Guggenheim fellowships. He was, his colleague Donald Zenger once wrote, "a scholar of the highest order."

Professor McIntyre was also a gifted teacher, winning two Wig awards here on campus and, in 1985, being named California Professor of the Year by the Council for the Advancement and Support of Education. In nominating him for the latter award, R. Stanton Hales noted: "It is known that one good question asked of McIntyre will earn at least two hours of personal instruction."

In lieu of flowers, members of the family have requested that donations in Professor McIntyre's honor be directed to one of two funds:

-- the Ewen McIntyre Upper Springland Fund; checks should be made out to the fund and sent to it c/o Ann McIntyre (17 Beaumont House, 15 N. St John's Place, Perth PH1 5SZ, Scotland UK). My understanding is that this fund helps support the home for the disabled where Donald and Ann's son, Ewen, currently resides.

-- the McIntyre Geology Fund at Pomona College (also called the Donald B. McIntyre-H. Stanton Hill Geology Fund), established in Donald's honor by H. Stanton Hill ('33) and Mary C. Hill in 1987; gifts/contributions intended for this fund can be sent to Pomona College, c/o Don Pattison, Office of Donor Relations, 550 North College Avenue, Claremont, CA 91711. In his remarks Stanton Hill directs that "this fund will be for the benefit of the students taught by Donald's colleagues and successors."

In addition, if anyone would like to share personal recollections of Professor McIntyre with his family and does not wish to send them to Ann directly, we would be pleased to receive, collate, and forward them along (please send such comments via email by December 1st, subject "Donald McIntyre", to https://webmail.yosemite.edu/owa/redir.aspx?C=4f27de7267174b68955d4b5890d81da5&URL=mailto%3aegrosfils%40pomona.edu). In a future communication, the department will also discuss developing plans for honoring Professor McIntyre at our annual alumni dinner, scheduled this year for the evening of February 17th, 2010.

The loss of such a highly regarded and cherished member of our community is never easy, and our thoughts are with Professor McIntyre's family in these difficult times.

So, What's Wrong With a Bit of Arsenic, Mercury and Sulfuric Acid in Your Drinking Water?

Top photo by Garry Hayes, bottom photo from the Kennedy Mine Foundation

The mining history of California's Mother Lode is fascinating, and in many ways downright scary. It is astounding to realize the length mine owners went to wrest those little flakes of metal from the ground, without regard to the Native Americans who inhabited the region for thousands of years, without regard to the communities of people both near by, and far downstream, and with a shocking disregard for their own workers, the men who risked their lives daily deep in the earth. And of course, the environment was an unknown concept. The gold was there; it therefore had to be pulled out. It was all about money, of course.

On our field trip this last weekend, we had a chance to explore some of the mine complexes in and around Jackson, on Highway 49 in the Sierra Nevada Mother Lode. Yesterday's post was about our tour underground at the Sutter Creek Mine. Another of our stops was at a fascinating city park, the Kennedy Mine Tailings Wheels.

The Kennedy Mine was one of giants of the hard rock mines of the Sierra Mother Lode. From 1860 to 1942, the mine produced around 1.7 million ounces of gold, worth about $17 billion at today's prices. At the time of the mine's closure (because of World War II), the workings had reached a depth of 5,912 feet, making it one of the deepest mines in the world (there are mines in South Africa that are more than 12,000 feet today). According to different sources, the length of the underground workings totaled at least 50 miles (and maybe over 100).

The earliest miners would have worked with candles (i.e. open flames), hand operated drills, and black powder for explosives (i.e. not so good in presence of open flames). Innovations in the late 1860's and 1870's included carbide lamps, steam powered drills, and dynamite (courtesy of Nobel, of the Nobel Prize). Still, not the best of work environments. No one wore hardhats. Miners operating the drills (called "widow-makers") got paid a lot more than everyone else, but developed silicosis within a few years, and died. Cave-ins and rockbursts were not uncommon events. One of the saddest episodes was in 1922 when a fire trapped 47 miners at the 4,600 foot level of the adjacent Argonaut Mine. Miners at the Kennedy worked feverishly to drill a tunnel to the Argonaut passage, but they were too late and the miners were lost.

The gold ore was brought to the surface and crushed using huge stamp mills. The tailings were treated with arsenic and mercury to remove the gold, and then stacked in huge piles around the mine property. Upon exposure to the atmosphere, many of the sulfide minerals were transformed into strong acids. Being upstream from the town of Jackson, the poisons were seeping into the domestic water supply. By 1914, the mine was "encouraged" by lawsuits and court actions to build a tailings reservoir a half mile away, and over two ridges from the mine property. The wheels were a unique invention used to transport the tailings slurry from the mine to the reservoir. The wheels had dozens of buckets that picked up the mush from the base of the wheel, and dropped them forty feet higher onto a flume that carried the debris to the next wheel. Four wheels were needed in total.

Jackson is a quiet tourist town today, and the wheels provide a photogenic stop on a tour of the Mother Lode. It certainly wasn't always picturesque, or quiet. The 100-stamp mill, and the wheels would have run 24 hours a day. The older photo (from the Kennedy Mine Foundation) shows the barren slopes and the spartan buildings that housed the wheels. The buildings were removed during World War II, and two of the wheels collapsed, in 1963 and 1971 (history of the wheels here).

The last owner of the Kennedy Mine had purchased the abandoned site in 1961, and her will stipulated that the property be preserved as a wildlife area and that the mine be protected as a historical site. The Kennedy Mine Foundation was established to do this in 1996, and they offer above ground tours of the mine site for a modest fee (especially for school groups).

Powder Monkeys and Dead Canaries: The Underground History of California's Mother Lode

It's late October, so it was time to introduce some of my students to the history of the Sierra Nevada Mother Lode, the site of the California's 1848 Gold Rush that brought hundreds of thousands of people to the west coast of the United States, and forever changed life in the Sierra Nevada and the rest of the state (and not for the better if you happened to be Mexican or Native American). Interest in gold has expanded as the price these days has reached $1,050 per ounce.

We explored Highway 49 from Sutter Creek to Columbia, one of the richest sections of the Mother Lode. Part of the trip was an exploration of the Sutter Creek Mine (the Lincoln Project), which offers tours of part of the underground workings of this off and on gold prospect.

The picture above is the entrance to the mine shaft. The white cylinder on top of the opening is the ventilation system that keeps fresh air flowing through the mine.


We were taken by modified jeeps about a quarter of a mile into the mine. Unlike most of the Mother Lode mines, the Sutter Creek operation is fairly horizontal. It is just a bit eerie to leave the daylight behind and to go plunging into the darkness. The ventilation system is quite noisy. One of the people on the tour (not one of my students, I'm glad to say) pretty much lost it and had to be taken back out (she was not aware that the tour was an underground tour).

We were taken to the safety room, a sort of refuge in a time of crisis for the miners. The room has strongly reinforced walls, air and water lines, first aid equipment, and communication lines to the surface. It also makes a nice little auditorium for talking about the early history of mining for gold. The demonstration of working by candlelight, as the earliest miners did, was especially effective. If you were wondering about the title, the canary refers to the actual practice of carrying canaries in the mine to monitor oxygen levels, and powder monkeys were the young men and children who were responsible for carrying dynamite around in the mine.

We walked through a section of tunnel that followed the gold bearing quartz veins, and looked at "gold" exposed in the quartz above our heads (I don't want to sound skeptical, but the "gold" is in a different place every time I tour, and it is always three or four feet above our heads where we can't see it well...). The equipment they used in the old days was downright, even insanely dangerous. Not just the explosives; the drills kicked up large amounts of silica the miners inhaled. Many died after just a few years from silicosis. But the pay was good...

The operators of the tour do a pretty good job of describing historic and modern methods of mining for gold, although it may stretch your budget if you are there on your own. They offer a decent discount for student groups such as the group we had yesterday. If you are interested in checking it out, their website can be found here.

After our tour, we headed up the mountain towards the town of Volcano for our second underground adventure, at Black Chasm Cavern. That will have to wait until the next post!

Light a Candle in the Darkness: Volunteering for Science in Your Community

Photo Source: Modesto Bee

I noticed some of my comic strips were running a theme of volunteerism this week. Well, now my blog is too (and this would also by my contribution to this month's Accretionary Wedge)...

Here in California, K-12 education is in pretty much a chaotic mess, and our children are being shortchanged in the worst way. Class size is growing, budgets are getting slashed, and some of our best teachers are being fired. These are bleak times, and our community college system is no better off. But I am proud of what my colleagues at Modesto Junior College are doing. You can read the story here, but in short we are bringing fifth graders onto our campus every other Friday to give them an experience in science and to introduce them to our college campus. Most of our division (biology, chemistry, physics and earth sciences) is volunteering to make the program a success. From the article:

About 60 students watched and performed experiments as part of MJC's Science Educational Encounters for Kids. Every second and fourth Friday of the month, fifth-graders converge on campus for a science lecture and then two 45-minute labs.

"We are drawing members of the community into the college. Some of these students maybe don't think college is a possibility, and we want to show them this is their community college," said Brian Sanders, dean of MJC's science, math and engineering division.

"Activities are a blend of fun and interest with real science," Sanders said. "We're not just playing with bubbles. We're matching the labs with the state's fifth-grade science standards."

And...these kids are a lot of fun, too. Full of energy and enthusiasm! Contact me if you would like more info on how we set up the program (hayesg at mjc dot edu).