Bringing Research to Light
The Research Staff of the North Carolina Museum of Natural Sciences includes experts in a wide variety of scientific disciplines who conduct exciting research investigations, maintain and expand the Museum’s natural science Research Collections, and participate in the Museum’s public education and outreach mission. Check this blog often to learn about all of the great science happening at the Museum!
Rocktober: Minerals Day of Earth Science Week
The beauty of minerals….Gemstones from the William Wallace Stephens Collection. An exhibit being prepped in the Collections space under the Museum. Photo credit Sean Moran.
The Mineralogical Society of America has a Minerals Day site here. https://mineralsday.org/ The three themes for Minerals Day are Science, Value and Beauty. You can download posters and other goodies at the site. Even better, you can advance your knowledge of mineralogy with talks and events found on the Events page here.
I’m here for the Science part. Minerals are information. Hard-rock geologists (igneous and metamorphic) like myself use the chemistry of minerals as the clues to the entire lifespan of a rock. (Soft-rock, that is, sedimentary geologists use chemistry, but also look at grain sizes of sediments.)
The chemical information contained in minerals allows geologists to measure the temperature and pressure of a magma, as well as the gases present – the mineral chemistry is frozen in place after eruption. Metamorphic rocks preserve the time-pressure-temperature path that they followed. The minerals present also show the temperature and pressure of peak metamorphism. Minerals like zircon provide the best absolute dating answers.
Minerals have value. If you read my earlier blog about my career, you know that the market value of molybdenum determined some of my career choices. A technological society like ours requires a lot of minerals to run. The tired old adage “if it can’t be grown, it has to be mined,” is still true. But even if it is grown, agriculture and forestry still require petroleum and steel for the machines, phosphates for the fertilizer, and all the specialty metals required to make machine parts. These days, they also require high-purity silica for silicon chips, much of it from Spruce Pine, North Carolina. An excellent BBC article is here. The construction industry would crash if crushed stone were not readily available from an aggregate quarry- roads, houses and cement would not be possible. A lowly mineral like pyrite (iron sulfide, FeS2) is routinely set aside during mining. It’s finding new utility as a semiconductor for solar power, which provides a greener source of energy as well as cleaning up mine waste heaps.
Minerals have beauty. Watch our social media accounts for new pictures. I think you’ll agree on this one.
Rocktober: Careers for the Sons (and Daughters) of Martha
They do not preach that their God will rouse them a little before the nuts work loose.
—Rudyard Kipling, 1907, describing the Sons of Mary in “The Sons of Martha”
Here we are again, second week of October, which means Earth Science Week. Our Community Engagement team asked for a few sentences about careers in the geosciences.
I did two projects as part of a Gifted and Talented program in high school. First was a time working with a geology graduate student polishing slabs for invertebrate paleontology. Second was working in a water quality laboratory. I learned how to do phosphate analyses using an Atomic Absorption Spectrophotometer, and also how to clean and acid wash glassware without filling my glove with 6M HCl. Those were my first exposures to geology and to the wonderful world of chemical analysis.
I was 13 when I started playing five string banjo, and 15 when I started acoustic guitar. I was playing regularly around town in bluegrass and old-time circles by the time I was a college student. This seems like an irrelevant tangent right now, but bear with me, please.
I discovered mineralogy, and then the fact that such a thing as geochemistry existed. I went to UNC as a Geology major, and knew that I had found my tribe. Field trips and camping with the other majors confirmed that I had found my place. I also found a wife during the six week Field Camp in geological mapping.
The Geosciences are the most interdisciplinary of all the physical sciences. If you have multiple scientific interests, there is likely a place for you in the Earth Sciences. If you have the 3D visualizations skills of an artist, the geosciences will feel very familiar. If you love the lab and the outdoors, geology is for you.
Careers in the Geosciences have one thing in common: We are the Children of Martha, the ones who make things work. Geologists are the ones who find the natural resources a technological society requires. Geologists find the water required to keep the people alive. Environmental geologists clean up afterwards. Geologists map the faults and the landslides, and camp out by the active volcanoes for observation. In the words of historian Will Durant, “Civilization exists by geological consent, subject to change without notice.”
It’s the geologists who provide the evidence that climate change is real and a constant part of earth history. Stable isotope geochemists track climate changes in ocean chemistry and water sources via fossil microorganisms drilled up from the ocean floor, looking at oxygen and carbon isotopes found in their shells. Organic evolution would not be as firmly embedded as a foundation of biology without the science of stratigraphy to underpin it. Geochemists provide the evidence for age of the Earth and Solar System. All of these research topics are still going strong, in geochemistry, meteoritics, cosmology and paleontology.
Careers in geology look like a safe bet for the coming years, because all of the problems facing mankind are fundamentally geological in nature. What happens when climate changes? It’s happened before. The answer is already there, written in paleontology, sedimentary geology and stable isotopes of oxygen and carbon. What are the signals that a volcanic supereruption is coming? Ask a volcanologist or an igneous petrologist, along with a seismologist. Where do we find the lithium and rare earth elements needed for “green” technologies? That’s the Economic Geology of ore deposits. Where and how do we store the carbon that petroleum products released? Ongoing research is locating places to do that, and identifying geochemical reactions that will sequester the carbon dioxide.
It’s not always easy. I started my career in the late 1970’s. The Oil Boom was running very hot at the time, and companies were hiring anyone who knew what a rock was for petroleum exploration. I finished my Geology degree at UNC in 1983, with an interest in exploration for mineral deposits. I was especially interested in molybdenum deposits, and other giant ore deposits formed by hot fluids circulating around granitic intrusions. I followed that interest to the University of Maryland, College Park, where I did a set of experiments on how molybdenum behaved in crystallizing igneous melts, and finished in 1986.
Along the way, I developed an interest in Irish traditional music, fiddle tunes and ceili music. The band Touchstone was playing in Chapel Hill and Carrboro frequently. Their keyboard player was a former member of the Bothy Band, a famous group that I had never heard of. I was hooked on the music, and wanted to learn it very badly.
Economics changed my career plans. The Oil Boom was followed by the Oil Bust in 1984-1986. The need for oilfield steel tanked, and so did the molybdenum market. There effectively wasn’t a job market for geologists at the time.
So I took my interest in geologic fluids and went on for a Ph.D. The same fluids that carry ore metals under one set of circumstances also drive volcanic eruptions under other conditions. Studies of catastrophic volcanic eruptions were a hot topic, so I went to Rice University in Houston, Texas to pursue that research. I ended up using an experimental petrology lab at NASA Johnson Space Center, where interesting things were always going on. I also started playing Irish music in the session at the former Red Lion on Wednesday nights, and graduated from guitar to tenor banjo.
One Ph.D and two post-docs later, I called it quits. I stopped applying for academic positions that were few and far between, and asked my wife where she wanted to live. She programs in the language SAS, and wanted to move back to North Carolina to be near her parents. SAS Institute moved us back to North Carolina. I was Dr. Mom for my infant daughter Carolyn, got her started on solid food, and taught her to say “banana”.
I was playing Irish music at someone’s house, when the fiddle player saw the bumper stickers on my guitar case. She asked all sorts of questions- Was I a geologist, did I have a Ph.D., did I have a Professional Geologist’s license in North Carolina? Yes, yes, and yes. Why?
She said, “The Museum of Natural Sciences is looking for a Curator of Geology.”
For more information on careers in the Earth Sciences, please visit the American Geological Institute, or the Geological Society of America.
Morganton Quake M2.7 2021-08-17
Residents of Morganton and vicinity got to enjoy a small earthquake at 9:19:28 last Tuesday morning. It wasn’t large, but it was felt. If you’ve never been in an earthquake like that, and wonder how it feels, you can stand by the joints between cement slabs in a parking deck. You’ll feel a bump, a jolt, as a car runs over the jointing. That’s what a small earthquake feels like.
The earthquake near Morganton was 5.6 kilometers down, about three and a half miles. It was also about 6.5 miles from the Brevard Fault, or the Brevard Zone Faults.
The Brevard Fault is one of the major scars of plate tectonics in the Southeast is. It runs from North Wilkesboro through Brevard, to just north of Atlanta and on into Alabama. It’s a major boundary, and in North Carolina it can mark the transition from Piedmont to Blue Ridge. On I-40 headed west, you cross the Brevard Fault at Old Fort, right as you start up the long grade to Black Mountain. If you take Highway 70 from Old Fort to Marion, you follow the trace of the Brevard Fault. In places you can look out the left window of the car and see mountains, and look out the right window and see the lower hills of the Piedmont.
The geologist’s job it to take the surface data and extrapolate to depth. Or you can just cheat and run a seismic survey that will tell you what the major features of the subsurface are. We combined those approaches in our third floor exhibit on North Carolina Geology. The cross section was drawn by NCSU Professor Jim Hibbard, a structural geologist. Professor Hibbard drew it on a 1:1 scale, same scale horizontally as vertically.
The mountains are built by thrust faults, low angle faults where the upper part, the hanging wall, travels long distances as a result of convergent tectonics. Thrust faults are shingled together, piled up into mountain ranges.
The cross section we show in our exhibit shows how the Brevard Fault is a part of a series of thrust faults off a major detachment. They curl up at the end like the runners on a sled and come to daylight. If you plot the hypocenter of the Morganton fault, it’s a bit above the Brevard Fault at depth.
But it’s not exactly there. Here’s where scale is an issue. At this scale, Albemarle Sound is the thinnest of blue lines. At this scale, only the biggest faults show up. The hypocenter may not fall directly one the Brevard Fault underground, but there are lots of similar, smaller, splays off that fault.
This isn’t necessarily the start of something big. The Appalachians in North Carolina are like an old house, and sometimes the floors creak.
Note added on Tuesday 24 August 2021
These old floors just squeaked again.
Today there was another small quake, M2.1, 5 km southeast of Gerton, NC. It was very shallow, only 0.1 km deep. Gerton is slightly west of Bat Cave, and Chimney Rock. Gerton is also 6.86 miles from Fairview, NC, which sits smack dab in the middle of the Brevard Fault Zone. The setting is similar to that of the Morganton quake I discussed above. However, the geologic map of the area shows a small normal fault that parallels Highway ALT 74.
A normal fault is “normal” as in “perpendicular to the surface.” One side is up and the other side is down, and the fault itself is nearly vertical. A thrust fault is over-and-under. The shallow nature and location of the Gerton earthquake suggests that it is the result of small motions on that normal fault.
Source: Robinson, G.R., Lesure, F.G., Marlow, J.I., Foley, N.K., and Clark, S.H., 2004, Bedrock geology and mineral resources of the Knoxville 1 degree X 2 degree quadrangle, Tennessee, North Carolina, and South Carolina (digital version), U.S. Geological Survey, Open-File Report OF-2004-1075. https://ngmdb.usgs.gov/Prodesc/proddesc_63783.htm
Walk
One thought leads to another.
Buddhists call it “monkey mind.” Some of us have bigger monkeys than others, and more of them, too. Putting vegan cheese on my sandwich led me to wonder about vegan milk, and how much milk one could get from a vegan, which prompted the revelation that it probably depended on how long one had a vegan hooked up to the milking machine, but that notion conflicted with vegan ideals about cruelty to living things. Luckily the conflict derailed the train of thought and I could eat my sandwich in peace.
The worst thing about monkey mind is that the bigger monkeys can’t be chased away for long. I’ve been returning to the thought of what it means to be American. Recent scientific studies changed the answer and the question to a much larger context, a polite way to say that the monkeys got loose.
For the longest time, I thought that it was travelling, moving. Everybody here came from somewhere else. Even the Native Americans and First Nations who greeted European arrivals came across the Bering Land bridge, or hugged the shoreline in boats. They were all going somewhere new, driven by…what? Curiosity? Boredom? Hunger? A vague feeling that someplace else has got to be better than this place? All of the above? Whatever reasons, they took the whole family, had no maps and didn’t stop to ask directions.
Movement is a fundamental part of the American psyche. Movement and speed. A surefire conversation starter in the US is, “So, what are you driving these days?” or , “What was your favorite car?” The travelling thread runs all through American popular music. You don’t have to look far- Springsteen springs to my out-of-date mind immediately, and the monkeys start singing Born to Run.
Active leisure pursuits support the fundamental nature of movement. Hiking, hunting, kayaking, fishing, running, bicycling, shopping. Yeah, even shopping. You could argue that it’s not so much about consumerism as it is about getting out and being stimulated by new sounds and sights. Hunting and slaying a big chocolate chip cookie is just a bonus.
We’re American. We go to new places. We go. But then the pack of monkeys took off in a different direction when reading gave me a different perspective..
There’s good agreement that Homo erectus arose about 1.9 million years ago in Africa. Now there’s good data showing that H. erectus lasted until 108,000 to 117,000 years ago, in Java . That is a heck of a long walk. Was Homo erectus just following the nose for food, or was there a fundamental primate curiosity leading them? Many species migrate back and forth, or spread to new territory. H. erectus walked.
Modern Homo sapiens is traced back to 300,000 years before the present. In 2019, a paper pushed bipedal locomotion in primates back to 11.6 million years. Get up and go isn’t just American, it’s a primate birthright with roots even older than Homo erectus.
Then a new article in the Proceedings of the National Academy of Sciences (PNAS) suggests that a genetic group of humans was isolated in northeastern Siberia. Gray wolves were likewise isolated by the vagaries of climate. The outcome was domestication of wolves at about 23,000 years ago. The two groups later walked out of the area, one split of canines and humans headed to the east and one to south.
It’s no coincidence that most dogs know the words “walk” and “ride” and get excited. Every day, my moose-sized dogs alerted me to activity on the street outside the house. My neighbors are re-enacting an ancient ritual of partnership, walking with the dog.
That is the fundamental thing that makes modern humans different. Not bipedalism, or agriculture, or war, or binocular vision. It’s the fact that dogs are part of our tribe, and we are part of their pack. We move, we travel, we go new places, and the dog goes along for the journey.
The ancient partnership between man and dog also explains how I feel with the loss of my dog, Colby, after 12 years. We recovered from surgeries at the same time, we comforted teenage girls through growing up, we walked the neighborhood countless times, and we grew gray in the face together. I was his human. Seizures and loss of his back legs meant a final trip to the NCSU Vet School. The dog bed is empty, as is the patch of morning sunshine, as am I.
Earth Science Week 2020: Geologic Maps
Of course, my computer had to misbehave during Earth Science Week. I got behind with my posting, so I’ll try to catch up now.
Geologic Maps Day is all about the importance of basic geological mapping. What kind of rocks are under your feet? How old are they? Trace elements may be present that are not good for your health? Where are the faults? Are the faults active? What other geological hazards are present?
Geologic Information Systems (GIS) revolutionized the science of Geography. As a senior at UNC in the 1980’s, I thought that Geography was dying. The advent of small computers and GIS software brought it back, healthier than ever. GIS also made Geologic maps more accessible than ever. One place to start is the interactive geologic map. It’s based on the 1985 geologic map of North Carolina, so it’s a bit out of date, but generally correct.
The geologic map you need, for curiosity, for real estate purchases, for development, for research, can likey be found online. There are Google Earth files for each state in .kml format, but these are not necessarily detailed enough for me. The better first place to look is the North Carolina Geological Survey. The first thing you might need to know is the Quadrangle you want. The United State Geological Survey divided the USA into squares of various sizes. You can find the one you want at the NCGS, too: here. Once you have that information, you can find the map you need.
The United State Geological Survey Geological Map Database is what I use most often. I find the Map View search to be the most useful. (It uses Adobe Flash player, so you may need to give your computer permission to run the plug-in. Also, Flash won’t be supported after December, so who knows what will happen?) You can zoom to the spot you want, hit the button on the right “List Pubs in View,” and you get links to the USGS publication there.
The publications and maps can be downloaded in a variety of formats, some of which can be used on your smart phone. When I started in Geology in 1978, I never would have thought that I would be using my cell phone as a combination GPS and GIS device. Google Earth alone would have kept me occupied for days.
Another less obvious way to learn about your geology underfoot: field trip guidebooks. The Carolina Geological Society meets once a year for a fall field trip, and publishes the guidebook and articles on the geology visited. It’s all free to download in pdf format. It’s the single best introduction to your local geology, because you can drive around just like the CGS and visit the sites.
Mountain Press has the Roadside Geology and Geology Underfoot series. These are akin to geologic field trip guidebooks, with mileage logs so you know where you are and what you are looking at. I buy these as gifts for friends heading off on vacation or moving to a new area. Just remember that some states have better outcrops than others.
Finally, Exploring the Geology of the Carolinas: A Field Guide to Favorite Places from Chimney Rock to Charleston, by Kevin G. Stewart and Mary-Russell Roberson. This is a guidebook that mostly sticks to state parks. This is nice for an unexpected reason- in a state park, the outcrops are likely to still be there. I’ve used old field trip guidebooks where the outcrops were bulldozed, or landscaped, or along a railroad track that was no longer there. The science is up to date and the geology and geologic history are well explained, because Kevin Stewart is a professor at UNC Geological Sciences. Go Heels!
So, a few exercises for your curiosity. What are the rocks underneath your home? What fault is closest to you now? If you live on the Coastal Plain, how deep is it to bedrock? Enjoy!
Rocktober: Minerals Day
Today, Monday, 12 October 2020, is the inauguration of Minerals Day. Science. Value. Beauty.
It’s a new part of Earth Science Week. Minerals Day is a partnership of the professional scientific organizations, the Mineralogical Society of America, the American Geological Institute. Industry partners are the National Stone, Sand and Gravel Association, and the Industrial Minerals Association-North America. Both science and value are represented by the governmental agency, the United States Geological Survey. Value, science, and beauty are the purview of the Gemological Institute of America.
The science? That’s my part- Minerals are information. Remember that. Ever since my first Mineralogy class, I have had a conviction that no geologic process could be understood until you understood the minerals involved. Minerals tell you how hot a rock was when it formed, how deep it was buried, how long ago it formed and was metamorphosed. Minerals tell you how much water was there. Many of these processes can be reproduced in the laboratory.
Value is in the minerals that provide the basic raw materials of a technological society. Materials science gets more and more sophisticated, and as it does, it needs elements from further down the Periodic Table of the Elements, more and more rare. The Rare Earth Elements, the Platinum Group Elements, and tantalum, and niobium. Those hard-to-find elements make up even harder-to-find minerals, but oh, so valuable minerals.
Then there’s value in the rare ones, the clear crystalline ones, rubies, sapphires, the gemstones. There are minerals that form that are the equal of any sculpture produced by men. That leads us to beauty.
So there’s talks available starting today, on minerals. The mineralogy of Mars, quartz, gemology, mining in the solar system (Oye, beltalowda? Anybody else watch the Expanse?), and the best way to fight the use of conflict minerals.
Schedule and links are at Earth Science Week webinars.
Consumers – The Most Potent Army Against Conflict Minerals. Vitor Correia, International Raw Materials Observatory
The Need and Solutions for Robots in Responsible Raw Material Exploration and Mining. Norbert Zajzon, University of Miskolc
Resources Beyond Earth: Enabling Future Exploration and the New Space Economy. Angel Abbud Madrid, Center for Space Resources, Colorado School of Mines
Advances in the Mineralogy of Mars. Elizabeth Rampe, NASA Johnson Space Center
New Insights into Wire Silver and Gold Formation. John Rakovan, Miami University
Gemstones: Timecapsules Connecting Us Through History. Aaron Palke, Gemological Institute of America
Data-Driven Discovery in Mineralogy and the Evolution of Planetary Bodies. Shaunna Morrison, Carnegie Institute of Science
May The Quartz Be With You. Shannon Mahan, U.S. Geological Survey
The Global Supply of Critical Minerals: Assessing and Tracking Critical Mineral Commodities Nedal Nassar, U.S. Geological Survey
When you go through all of those, these are still excellent videos of state of the art mineralogy at the Centennial Symposium for the Mineralogical Society of America.
Rocktober: Earth Science Week 2020
Here we are in Rocktober, the second week of which is Earth Science Week around the world. It is sponsored by the American Geoscience Institute (AGI), an association of associations, including the Geological Society of America, the Mineralogical Society of America, and many others.
This year’s theme is Earth Materials in our Lives. As the ESW website states:
Earth Science Week 2020 will explore a host of related questions: As scientists, engineers, inventors and others use raw materials to design innovative technologies and goods to meet human needs, how do we evaluate costs and benefits of using Earth materials? How do we adopt policies and practices that allow us to take advantage of the unique properties of raw materials efficiently, generating value while minimizing negative impacts both locally and globally? How do we address the complex, interrelated issues like resource management, waste management, biodiversity, climate change, circular economies, life cycle analysis, and models of sustainability?
Scientific and technological literacy includes understanding where stuff comes from. Geologists are fond of saying that if you can’t grow it, you have to mine it. (And you may have to mine phosphorus before you can grow it.) Professor John Hughes noted in his talk at the Centennial Anniversary for the Mineralogical Society of America in 2019 that he came from Vermont to D.C., a trip of a few days or hours. A century before it would have been a much longer and more difficult trip. Check out this map from the Library of Congress of roads and railroads of 1919.
Professor Hughes noted that the advances in travel and lifestyle are all made possible by the success of resource extraction industries, mining and petroleum. I would like to add that the people who most enjoy the benefits of our technological lifestyle tend to be the most removed from the earth materials at the base of that economy.
For instance, Rare Earth Elements (REE). The REE are used in green technologies, smart phones, computers, semiconductors, magnets, and on and on. An electric guitar pickup with neodymium magnets is 2-6 times stronger than a regular pickup, meaning your heavy metal just got heavier. In 2017, the US produced no REE mining concentrates. Then, and now, the trade is dominated by China and the Bayan Obu deposit in Mongolia, a real oddball of a carbonatite ore body. That, my friends, is a genuine national security issue.
One source of REE is the mineral monazite. Rivers in the Kings Mountain area of North Carolina contain placer deposits of fairly high-grade monazite, examples of which we have in our Geology Collection. Here’s a hypothetical discussion question: How do we mine those placers, if they are needed for national security resources? How do we preserve clean water for the nearby cities? Clean water is one of North Carolina’s greatest natural resources. How do we restore the river valleys? Monazite also contains radioactive elements like thorium and uranium. What do we do with those leftovers? Geologists are involved at every stage: exploration, mining, separation, hydrology and remediation.
Now we’ve come full circle to this year’s Earth Science Week.
Kids eventually learn that milk comes from a very funny-looking part of a cow’s underside, not from a carton or jug. A single cell phone comes from many extractive industries worldwide, not from the store. A scientifically and technologically literate society needs to understand that their “footprint” involves much more than the geochemical carbon cycle. You can download a flyer on the materials in a mobile device from the USGS.
In pursuit of scientific literacy, the Earth Science Week website provides resources for education, for teachers, and for students, and resources in Spanish. Each year I order the ESW Toolkit, full of resources about each year’s theme. It always has fun stuff in it.
But it isn’t a week devoted to mining. Each day of ESW has a different focus:
Sunday, October 11 is International Earthcache Day. This is a lot like a GPS scavenger hunt.
Monday, October 12- Minerals Day. For me, minerals are information. For other, beauty. This day is about both.
Tuesday, October 13- Earth Observation Day. This is the day for engaging students and teachers in remote sensing. It gives a more global vision to your science.
Tuesday is also No Child Left Inside Day. NCLI Day encourages students to go outside and research Earth science in the field. Get dirty, swing a hammer (safely) or do a field trip.
Wednesday, October 14- National Fossil Day. ‘Nuff said.
Thursday, October 15 Geoscience for Everyone Day. Geology has a diversity problem, and this is one day for addressing that issue.
Friday, October 16- Geologic Map Day. I quote the ESW site: Hosted by the U.S. Geological Survey, Association of American State Geologists, National Park Service, Geological Society of America, and the National Aeronautics and Space Administration in partnership with AGI, this special event promotes awareness of the study, uses, importance of geologic mapping for education, science, business, and a variety of public policy concerns. You’ll get a blog post from me on finding geologic maps for your needs.
Saturday, October 17- International Archaeology Day. This day is hosted by the Archaeological Institute of America. Check them out, because this is one area where I can’t help you.
Happy Earth Science Week!
Sparta, NC, 5.1M, 3.1km depth
Anyone out of bed on this Sunday morning at 8:00 a.m. probably felt an earthquake. It was located in the mountains, near Sparta, NC. It was fairly shallow, about 2.3 miles down.
You can help out the United States Geological Survey with their Did You Feel It? Program. This citizen science program helps with models of seismic wave propagation through the upper crust, and prediction of the effects of future earthquakes. It will have input from people from all over three states.
The epicenter was in part of the mountains we call the Eastern Blue Ridge in the most generic models. The geology of this part of the mountains is complicated, so we need some boundaries. You can see in the figure above that it can be simplified.
To the southeast is the Brevard Zone Fault, which is a major geologic feature, running from north of Atlanta, through Brevard (duh, geologists aren’t real creative with names). It crosses I-40 at Old Fort, right at the base of the big grade up the mountain to Black Mountain and Swannanoa. It runs through Marion and up to North Wilkesboro, where it splinters into several faults. When you travel 421 from Winston-Salem to Boone, you crest a hill east of Wilkesboro and have a splendid view of these faults in the Yadkin River valley.
To the southwest and northwest, the Eastern Blue Ridge is bounded by the Gossan-Lead Fault, as it’s known in Virginia. It has a few other names as it winds to the southwest. The Gossan-Lead Fault dives beneath this package of rock and forms the lower, bottom, border.
It’s a thrust sheet- the upper layer of a package of crust that was pushed from east to west over the edge of North America. It ramped up onto the continent like a tractor-trailer rig hitting a small car. Several different collisions created the Appalachians, and thrust faults are the result.
This is a very simplified version of thrust faulting. It would take a lot more work to identify the actual fault, but in that region, it’s an old thrust fault.
Don’t panic.
This isn’t evidence of active faulting. Faults are the scars of plate tectonics, lacing the geologic maps of eastern North America from Alabama to Canada. I’ve described North Carolina’s faults as a creaky old house. Sometimes there’s a little motion on one to relieve residual stress. Creak. Crack. Earthquake. It’s fair to say that the stress is transferred to us.
Edit added on 10 August 2020: The good people at the Incorporated Research Institutions for Seismology (IRIS) have provided a Teachable Moments PowerPoint presentation about the Sparta, NC earthquake. It combines excellent science with good graphics. You can also find other goodies if you explore their site.
Rubies? Walks like a duck…..
Here’s a puzzle to keep you occupied.
Suppose:
- It looks like a duck.
- It quacks like duck.
- It walks like a duck.
But when you do an X-Ray, it has the skeleton of a snake.
Ruby (?) under plane light
Synthetic ruby (?) fluorescing under UV light
We received a magnificent donation of more than 400 gemstones (more on that later), all faceted. As part of the curation process, these need to be identified, or verified. This specimen was marked as a ruby. It’s red (looks like a duck) and it fluoresces in ultraviolet light (quacks like a duck). But the skeleton…….
The National Science Foundation funded an excellent infrared spectrometer for my lab, and one of the most useful attachments is Attenuated Total Refectance (ATR). The sample is held against a diamond, and the infrared beam bounces off. Anything you can put against that diamond- powder, lab alcohol, gemstones, anything except sulfuric acid- you can get a spectrum on. There’s a device to hold the sample down, and it’s even a torque wrench so you can’t tighten it too much. It’s robust enough that I use it to teach middle schoolers about spectroscopy.
ATR is great for mineral identification. It gives information about the basic crystalline framework for each different mineral. A ruby is the mineral corundum, aluminum oxide, of Al2O3. Here’s a corundum reference from RRUFF, which is a public database for mineral data.
Here’s how you read one of these. The graph shows areas where infrared radiation is absorbed. If there’s nothing there, 100% gets through. The “peaks” in this case hang down like stalagtites from the top of the graph. Units on the X-axis are reciprocal centimeters (cm-1), the number of waves per centimeter. If you want to think about it as frequency, low frequency is to the right and higher frequency is to the left. Error in the x is ±4 cm-1.
But now let’s compare our unknowns with reference material. The RRUFF sample has a major absorbance at 553 cm-1, with a small shoulder peak at 634 cm-1. The reference from the Museum Collection, NCSM 4840, probably needs to be revisited. It has only an absorbance at 628 cm-1. Perhaps it is a synthetic mineral of some sort. The Ruby (?) unknown is our strange duck, and it, too, lacks the 553 cm-1 absorbance. So do the other two unknowns from this collection, a yellow sapphire and an “alexandrite” sapphire.
Next look at the RRUFF reference mineral. The peaks are nice and sharp. This comes from a lot of aluminum-oxygen bonds lined in exact crystalline marching order. The %transmittance on the y-axis is also about 40%. This is a very strong absorber. In all of our unknowns, the peaks are much weaker, and broader. This means that they are not as crystalline as the RRUFF reference, and it’s possible that we are looking at the coloring agent, scattered throughout the gemstone. The gemstones are less crystalline, which is common in synthetic minerals.
So, our red duck of a gemstone is not a corundum. It is also not:
- Spinel
- Garnet
- Cuprite
- Glass
- Tourmaline (rubellite)
- Red beryl
If you have ideas, or just want to fool around with the data, you can find reference materials for ATR at RRUFF to test your hypotheses. Download the spectrum, but when it come time to save it, use .csv instead of .txt. Then open it in Excel or another spreadsheet program and make a graph of the data. You may need to change to format on the number.
Good luck!
Then something changed without warning…
Stephen King had an interview on NPR where he shared his thoughts on horror. I can only find that interview in a format I can’t play, but the essential part was that there was horror in the everyday things that go very wrong: the family St. Bernard gets rabies, or a car is possessed and haunted, or a bullied schoolgirl becomes telekinetic. The interview would have been about 1999 or 2000, sometime after the death of our son, so I understood immediately. The horror that bends your mind and breaks your heart doesn’t come from the supernatural. It comes from the everyday.
I’ve tried for a week now to write a blog about the volcanic disaster on Whakaari/White Island, New Zealand. It just keeps turning into horror: a holiday excursion interrupted by a volcanic eruption. There were 47 people touring the island when it erupted without warning. At present, sixteen have died, and two are missing. You can get a scientific look at the Smithsonian Global Volcanism Project, a week-by-week and day-by-day view from GeoNet, which monitors the volcano, or a more human view from the New Zealand Herald’s coverage.
My mineralogical research is on the apatite mineral group, which contains fluorine, chlorine, OH (two-thirds of a water molecule), sulfate and carbonate. Listed in order, we can relate these to magmatic HF, HCl, H2O, H2SO4, and CO2, all the liquids and acids involved in catastrophic volcanic eruptions. I’ve been interested in pyroclastic eruptions for a long time now.
I can answer one of the questions many people want to know, so I’ll do that.
Why was there no warning?
Whakaakri/White Island is an andesite volcano, part of an island arc over a subduction zone. These volcanoes explode instead of flowing like Hawaiian basalt. They are inherently unpredictable, but volcanologists have made huge advances in monitoring over the last thirty years. Ground tilt, seismic activity, seismic signals for eruptions, infrasound, gas cloud monitoring….Active volcanoes like Soufrierre Hills in Montserrat and White Island in New Zealand are heavily monitored. Chlorine and sulfur come from the magma? Then monitor the gas cloud for increases in chlorine and sulfate. Harmonic tremors mean magma is on the move? Then wire this island with seismometers in a network. Does rising magma change the surface? Then install tilt meters to keep track. Some observatories listen in with infrasound, very low frequency sound, to detect the growl of an eruption, and lightening sensors to watch for the lightening in the erupting ash cloud.
Here is the disconnect between geologists and the public: If asked to draw a volcano, people will usually draw a stratovolcano flying a little plume of steam. Geologists will draw what is underground. Prediction involves what’s underground. Once it’s above ground, it’s too fast and too late.
There’s the magma chamber underground that we can only sample after an eruption, when the contents are spread out over the countryside. Underground, water in the magmatic liquid builds up as magma cools and crystallizes. Water bubbles eventually form, and it is exactly, I mean exactly like a two-liter soda dropped on the floor. The pressure drops, the bubbles expand exponentially, and the volume of the liquid plus bubbles skyrockets, breaking the container. The difference is about 600°C and a lot of rock instead of cola. Also imagine gas from two two-liter bottles with only one exit. A magma sometimes has input of gas or fluids from another magma lower in the system, triggering an eruption.
This is Bingham Canyon , a fossil hydrothermal system. The different colors are different parts of the system. It was mined for copper and some gold. Picture courtesy of Google Maps. The scale bar is one mile.
Underground is the hydrothermal system surrounding the magma. Hydrothermal is exactly what it sounds like- hot water. These systems are extensively studied because they supply geothermal energy and form ore deposits. They wax and wane, like at Yellowstone, and can supply surface clues to the temperature underground. In addition, Whakaari/White Island is an entire mountain under the sea, which is trying to get into the volcanic system all the time.
There’s a complex interplay between the magma and the hydrothermal system. The magma supplies heat to the system, and sometimes magmatic fluids. The hydrothermal system sometimes gets into the magma or heated rocks and things explode, what is called a phreatic eruption. (Here’s a link to a good interview from a New Zealand geologist. ) The hot circulating groundwater of the hydrothermal system also changes the rocks into something softer and less competent, a process called hydrothermal alteration. Hydrothermal alteration puts the “yellow” in Yellowstone. The hydrothermal system may also deposit minerals as it cools, making an impermeable barrier.
The Grand Canyon of Yellowstone. The yellowish color is hydrothermally altered rock. Photo courtesy of the National Park Service.
The deep magmatic processes and the hydrothermal system can’t be monitored directly. You can stick a thermometer in a fumerole up top. You can monitor the gases leaking out the top. You can look for large-scale seismic signals. The large-scale catastrophes involving eruptions usually give clues for warning. Small scale phreatic eruptions give no warning, but are equally deadly. What is going on at depth is generally quiet until something changes without warning.
Whakaari/White Island experienced a phreatic eruption with no warning last Monday, killing eight people immediately. The numbers of the injured who are dying is creeping upwards. At Mount Unzen and Galeras, teams of professional volcanologists were killed. At Unzen, the lava dome collapsed without warning, uncorking a pyroclastic flow. At Galeras, scientists were caught in the crater by a (probable) phreatic eruption with no warning. At Mount Ontake, a phreatic eruption killed sixty-three tourists without warning. All of these cases are similar. Based on the current conditions and state of knowledge, it was safe to do what they were doing. Then something changed. Without warning.
Communications between geologists and the public fall into the gap between geological time and human schedules. Volcanologists have all studied, seen, and experienced enough that they can tell you with a fair amount of certainty what’s going to happen. They can even tell you where the uncertainties are. The drawback is that volcanoes that explode are very unpredictable and have their own clocks and calendars. People tend to ignore the warnings because the warning seems vague, indefinite. It’s not a time and date for the calendar.
Then something changes underground, without warning. Human history shows us that this always happens sooner than anyone really expected, and that management by panic attack never works.
Historian Will Durant said it best: Civilization exists by geological consent, subject to change without warning.
Research & Collections 