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Ethan Yackulic is currently a data scientist for the USGS in Flagstaff, AZ. He recently completed his master’s degree at Northern Arizona University with Dr. Nicholas McKay in environmental science.

Introduction

The wind howled and the clouds grew darker as the lake whipped the shoreline with increasingly violent whitecaps. I could sense the anxiety of the rest of my field team, perched precariously on a makeshift coring platform in the middle of an alpine lake. It was only October, but winter was announcing an early and unprompted arrival and we were miles away from our work vehicle and further still from the closest signs of civilization. Our margin of error had seemingly shrunk that morning; we enjoyed warm, gentle weather during our first few days at Crater Lake (no, not the famous one in Oregon), but on our last day, conditions were deteriorating from the get go.

The coring platform fits up to the 3 people on board at all times and is equipped with 0 additional vessels in case of emergency.

While most of the crew focused on removing one final sediment core from the deepest basin of the lake, Charles Mogen had drawn the proverbial short straw and found himself paddling a constantly-deflating packraft across the lake with a car battery between his leg. A dangerous job in calm weather had become a death paddle as Charles valiantly tried to fill in the remaining transects necessary to illustrate the underwater topography of the lake bottom.

Crater Lake from up high on a calmer day. Note the moraine feature in the foreground, an artifact of the past glacial period.

For a moment, I was transfixed by the goal of our work; understanding the changes occurring in and around the lake through time and during periods of climatic change. Since the last ice age (~12,000 years ago), the landscape had shifted numerous times, from a glaciated cirque basin, to periods of more/less water than today. These shifts were also pronounced in changes in vegetation, as treeline fluctuated above and below the elevation of the lake and ecological niches opened and closed.

I jolted back to the present. A bolt of lightning cut through the sky above the lake basin and produced an earth-shattering thunder, signaling what we already knew: we had overstayed our visit to Mother Nature’s mountain oasis, and it was time for us to leave. A team of pack animals arrived and we quickly shuttled our gear onto the mules and horses and made haste toward the parking lot before dark. By the following evening, there was more than a foot of snow resting on the calm shorelines of Crater Lake.

The mules and donkeys provided through the US Forest Service were the real heroes at Crater Lake.

Location map of the Four Corners region showing the San Juan Mountains (circled) and Crater Lake (star).

Purpose

To the people, plants, and animals living in the Southwest, water is life. The San Juan Mountains in southern Colorado are the headwaters to the Rio Grande and Colorado rivers, massive watersheds that support vast communities and ecosystems. Understanding how past climates shaped the paleoenvironments (paleo-“past”) of the Southwest is essential to forecasting how modern, human-induced climatic changes might affect water availability for downstream recipients. This research not only informs our understanding of how regional temperatures changed since the last ice age, but also how temperature variability affects the distribution and storage of precipitation.

Slaving away in the field on a goat trail somewhere outside of Silverton, Colorado.

Supporting Details

To understand how temperature and precipitation trends have changed over the past 10,000+ years, I looked at sediment cores that were taken from alpine lakes (i.e. high elevation lakes—around 10,000 feet above sea level) in southern Colorado. Alpine environments are sensitive to slight changes in climatic conditions, and lakes can provide natural records of these changes through the preservation of organic and inorganic material in mud and sediment. It’s like a dirt time capsule: the presence of different organisms, woody fragments, and even pollen and proteins can provide valuable information about environmental and climatic conditions.

The best part of my work was undoubtedly spending time in the field, where I was given the difficult task of hiking across the beautiful peaks and valleys of the Rocky Mountains in search of ancient mud. Remote locations are preferred, because they are less likely to have been tampered by various forms of human disturbances over the past couple 200+ years. This led Charles and me to core some of the prettiest and least accessible lakes I have ever seen, often climbing over rocky passes where no established trails existed.

Charles Mogen (left) ingratiating himself to the camera while the author examines his mud tube.

Cole Webster keepin’ it metal while looking for rocks in the Crater Lake watershed.

When I wasn’t in the field, I was working with a hyperspectral camera. Put very (very) simply, this hyperspectral camera is sort of like a photo scanner. These long tubes of lake-mud were split open and scanned under the machine. What makes the camera so unique is its ability to detect the individual wavelengths that make up the colors we see with our eyes.  So, when I scanned my sediment cores, I was looking at wavelengths that could be related to the concentrations of different photopigments, such as chlorophyll. If that sounds complicated, that’s because it is—so much so that I HAD to take a trip to Switzerland to be trained on how to use the machine. I won’t dwell on how I used the machine, but suffice to say, the beers, chocolates and exotic meats alone made my “business” trip worth it.

 Wrap-up

The results from my work showed that spectrally-inferred concentrations of phyocyanin (a photopigment found only in cyanobacteria (“blue-green algae”)) in the sediment cores from Crater Lake aligned with global temperature reconstructions over the past 12,000 years. In other words, the concentration of cyanobacteria was responding to changes in temperature: warmer periods caused a proportional increase in the amount of cyanobacteria while colder periods caused a proportional decrease. My study showed that Crater Lake warmed rapidly after the end of the last ice age until around 7-8,000 years ago, when the environment was likely drier and warmer than today. Temperatures remained high until around 5,000 years ago, and there is significant evidence that the water level at Crater Lake during this time period was much lower than at present. This is likely due to a decrease in snowpack, as winter precipitation is thought to have decreased during this period and summer temperatures were regularly warmer. I believe that this is strong evidence of the potential peril of future 21st century warming; as perennial snowpack decreases, water bodies will likely start to shrink as evaporation rates increase. More work is necessary to confirm the past relationship between temperature and moisture, but this study is evidence enough that something as simple as mud can provide valuable information that can help develop practical policy decisions about water management.

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My research would not have been possible without the support, guidance, and friendship of my advisor, Dr. Nicholas McKay (right).

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Kirk Schleiffarth is currently a Ph.D. candidate at Northern Arizona University (2014-present). He has experience studying a variety of volcano-tectonic provinces with a variety of techniques. In 2010, he spent several months monitoring and cataloging volcanic activity at Colima volcano in Mexico. From 2012-2014, he investigated the Eocene Challis Volcanic Field in central Idaho for his master’s degree using geochemistry and geologic mapping. In 2017, Kirk spent 2 months in New Zealand comparing hyperspectral and geochemical results from the Tongariro volcanic complex for a volcano hazards project. He currently works on understanding the tectonic significance of volcanoes in Central Anatolia (Turkey) using geochronology, igneous geochemistry, and structural geology. Kirk is an executive committee member of TravelingGeologist.com.

Volcano Questions
I was half asleep in my tent on the slopes of Colima volcano in Mexico after a long day of monitoring its activity. I purposely left the tent cover off in order to keep cool but more importantly, so I could keep an eye on the volcano in case it erupted during the night. Around 3 a.m., the volcano came to life; with a sudden and thunderous roar, it spewed ash into the sky and triggered an avalanche of glowing, hot rocks down its slopes directly towards me. I excitedly yelled at the other scientist I was working with and scurried toward the monitoring equipment to make sure we were collecting the data we needed. Once we checked that the equipment was working, we watched the volcanic event unfold, snapping photos of the impressive display. The eruption was a relatively brief episode, and within 10 minutes all was quiet. The thrill of observing even just a small part of the volcanic process was enough to keep me up for the rest of the night. I began to think: Why did this volcano form here? Why did it erupt now? When would it erupt again?

Hot rocks cascade down Colima volcano in the middle of the night. Photo by Kirk Schleiffarth.

Who Cares?
These questions drive me to research volcanoes all over the world. One of the major themes of my research has been the quest to understand why volcanoes are located where they are. What controls where they form? Why do they form in some places and not others? Ultimately, this matters because volcanoes are dangerous and variable. They can have devastating effects on property, landscapes, ecosystems, local and international economies, climate, and human life. My Ph.D. research is on volcanoes in Turkey because little is known about why they formed there and how they are related to the regional plate tectonics. To study these poorly known volcanoes, I sought to collect rock samples from the slopes of more than 20 volcanoes in central Turkey, hoping they would provide information on how the magma formed, how deep it formed, and when it erupted to create these interesting volcanoes.

Looking towards Erciyes volcano, the largest of the region, from the north. Photo by Kirk Schleiffarth.

Fieldwork
Fieldwork is often the highlight of the research process for geologists; and that certainly was the case for me in remote, central Turkey. After a year of prep work, including reading scientific literature, pouring over geologic maps, and studying the region on Google Earth from every angle possible, actually being there felt a little unreal and overwhelming. I quickly learned that fieldwork in Turkey is different than fieldwork in the western U.S.A. and in some ways, much more luxurious. Instead of camping, we stayed in hotels. Instead of hiking long distances, we drove a rental car. Instead of fearing bears or rattlesnakes, I feared the Kangal shepherd dogs. Some of these differences were a product of the nature of my work; I had to cover more than 500 km and collect samples from each volcano along the way! However, some of these differences were unique to Turkey just like the volcanoes I came to study.

Breaking rocks with Mike Darin. Photo by Barbaros Demircan.

A kangal dog protecting his sheep. Note the spiked collar. Photo by Mike Darin.

Fear of the Kangal Dog
Early on during my first field season, I collaborated with proto Dr. Mike Darin for a couple of days on an older, eroded volcano that we thought might represent the oldest in the region. We marked a waypoint where we wanted to collect a rock sample, and watched our GPS device carefully as we drove up a bumpy, gravel road. We took the road as high as we could to a small saddle in the topography. The rocks we wanted were up on the mountain to our left, along with a flock of sheep and their K9 shepherd. We both sunk our heads in frustration, knowing that we shouldn’t approach a flock of sheep protected by a Kangal dog – they are known to be overly protective and aggressive. I asked myself if I really cared about this sample that much. After some discussion, Mike and I decided that we needed the sample but had to move quickly and quietly to not get the attention of the dogs. We hiked silently up the mountain through tall grass, hunched over to avoid being seen. I suddenly felt less like a geologist seeking samples and more like a soldier going into combat. The only thing I had to defend myself however, was a rock hammer and a tiny hand lens used to break open and look at rocks up close – a common accessory for most geologists. Fortunately, I only had to use my geology tools for their intended tasks. We collected a sample and returned to the car unnoticed and unscathed with a new, very important sample.

A scenic view of remote Central Turkey where old volcanoes have eroded into various small mountaind and hills. Photo by Kirk Schleiffarth.

New Hypothesis
I collected many other samples over the following months and I slowly became more familiar with the various volcanoes in central Turkey. That summer’s fieldwork yielded great initial results, which helped me develop a new hypothesis that I was eager to test. My theory was that the volcanoes of central Turkey were getting younger to the southwest towards the Mediterranean Sea; an idea that had not been suggested before. If this is true, it will have significant implications for understanding why volcanoes are present in central Turkey and where they might erupt again. The following summer, I returned eager to test my hypothesis. I knew the towns, I knew the roads, I knew about 10 words in Turkish, I knew to stay away from sheep, and most importantly, I knew the volcanoes. With my enthusiastic Turkish field assistant(s), we scoured the countryside, collecting over 100 samples from more than 20 different volcanoes from an area greater than 15,000 km2. We were hoping to get isotopic ages that would prove my hypothesis correct and systematically worked our way towards the southwest.

Taking notes at a small outcrop in Central Turkey. Photo by Mary Reid.

Mowing down grass on our way to get a sample. Photo by Kirk Schleiffarth.

Curious Farmer
Several of the volcanoes that we collected samples from were now discreet, eroded, and unassuming hills, making it difficult for locals to recognize or appreciate the interesting geology around them. We had become accustomed to explaining our work to suspicious locals, jumping fences, and navigating bad roads, which is exactly what we had to do to collect a sample from Hoduldag volcano. This volcano rises above beautiful grassland and is in one of the more difficult-to-access and remote regions of the field area. After a heinous drive, jumping a fence, and collecting the samples we needed, we started the hike back to the car. It was parked on the side of a gravel road near what seemed to be an abandoned farmhouse. As we got closer, we noticed a man emerge from the small building. From over a hundred meters away, he began yelling and asking in Turkish, ‘What are you doing here? This is my land, what are you doing here?’ My field assistant told him we are geologists but the man insisted we come to him. It seemed he needed a better explanation.

Chatting with the curious farmer after collecting samples near his home.

We spent the following several hours with this curious farmer in his humble home, sharing stories while he insisted we drink his tea and eat his fresh mushrooms. He abstained from eating because he was observing Ramadan. Despite living in a very small home with no electricity, this man was eager to share everything he had with us and was extremely curious about our work and the rocks beneath his land. We briefly told the farmer that the mountain in his backyard was an old volcano, one of many that covered the countryside and erupted frequently not so long ago, geologically speaking.

Wrap-Up
The volcanoes of central Turkey have a range of ages between ~12 and 0 million years old and appear to decrease in age towards the southwest near the Mediterranean Sea. In general, my hypothesis was proven correct but it’s always a little more complicated than it might appear. These results show that yes, there is a regional southwestern pattern of where and when the volcanoes first erupt, but there is some variability at a smaller scale. I think the volcanoes of central Turkey generally formed above a southwestward migrating deep mantle source (or in geology terms – flat subduction in the Oligocene and early Miocene eventually led to southwestward slab rollback and magmatism). I attribute the irregularity in the pattern to many factors mostly related to variability of deep rocks and faults through which the magma had to rise. Although my fieldwork was completed that summer, I am still in the process of analyzing other data and thinking about why those volcanoes formed where they did and what the observed age pattern actually means. Often figuring out the explanation of geologic observations begins with identifying regions on Earth with similar patterns controlled by known processes. Similar volcanic patterns of decreasing age towards the continental margin is seen in many places (e.g., western U.S.A., central Mexico, Italy, New Zealand, etc.) but Turkey remains unique and interesting, much like the field experiences I had. I look forward to studying more volcanoes and the all experiences that come with it.

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All work funded by NSF Award Abstract #1109826
COLLABORATIVE RESEARCH: Central Anatolian Tectonics (CD-CAT): Surface to mantle dynamics during collision to escape https://www.nsf.gov/awardsearch/showAward?AWD_ID=1109826&HistoricalAwards=false

Further Reading:
Scientific publication
https://www.researchgate.net/publication/315977631_Shallow_melting_of_MORB-like_mantle_under_hot_continental_lithosphere_Central_Anatolia

Non-technical description of multidisciplinary project
https://www.esci.umn.edu/groups/CD-CAT/CD-CAT-101-Non-Technical-Description

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Jake Lowenstern is currently the Project Chief for the Volcano Disaster Assistance Program.  From 2002-2017, he served as Scientist-in-Charge of the Yellowstone Volcano Observatory. To study the interaction of magmas and their overlying hydrothermal systems, he applies techniques ranging from gas and and isotope geochemistry to igneous petrology to U-Th-Pb geochronology.  A 1986 graduate of Dartmouth College, he spent the following year on a Fulbright fellowship to Catania Sicily (Italy).  He later earned an M.S. and Ph.D. at Stanford University, finishing in 1992.  He spent a year as a researcher at the Geological Survey of Japan (Tsukuba) in 1993. Since then, he has worked for the USGS in Menlo Park, CA.  In 2000, he received the Lindgren Award from the Society of Economic Geologists and in 2006 was an AAPG Distinguished Lecturer. He was elected a fellow of the Geological Society of America in 2011.

Until last Fall, I served as the Scientist-in-Charge of the Yellowstone Volcano Observatory, which involved lots of coordination between my organization, the USGS, and observatory partners at universities, state geological surveys, and other organizations.  My job required interaction with scientists covering multi-disciplinary topics including seismology, geology, and hydrology.  Anyone familiar with the topic of the “Yellowstone Volcano,” knows that the job requires considerable public outreach to provide a summary of geologic/volcanic activity at Yellowstone.  This is especially challenging at Yellowstone because an army of Yellowstone followers creates volumes of daily blogs and vlogs interpreting the latest wiggles of the seismic records.  Much of their interpretations are inaccurate, misguided, or even intentionally misleading, creating additional complications for those whose job is to provide official warnings and updates to the public and local officials.

Geochemists explore Washburn Hot Springs. Photo by Cindy Werner, USGS.

Porkchop Geyser, Norris Geyser Basin. Photo by Jake Lowenstern, USGS.

Old Faithful, in Yellowstone’s Upper Geyser Basin. Photo by Jake Lowenstern, USGS.

Geochemistry research: Another part of my job at Yellowstone was as a research scientist, to study the gases and waters that emerge from the world-famous geothermal system.  Those gases reflect a range of fluid sources and processes that take place between the surface and underlying magmatic system:  magma rising from the mantle, heat driving metamorphism of crustal rocks, sediments reacting with migrating fluids, and infiltration of surface water with its atmosphere-derived gases.  Our task as scientists is to interpret how these gases and waters reflect what’s happening beneath the surface, to provide a record of “background” fluxes and chemistry of the geothermal system, and to tease out information about the magma system through study of the geothermal volatiles.

Yellowstone has an estimated 10,000 thermal features spread out over about 85 distinct thermal areas, some of which are over 25 km from the nearest road.  The park is enormous, with ~9000 km2 of terrain— only about 0.6% of which is defined as geothermal— so it’s not a simple task to get a representative sampling of the park’s geothermal features.

To undertake this research, my colleague Deb Bergfeld and I explored a considerable fraction of the Yellowstone backcountry, as well as dozens of thermal areas that line the park’s roads.  We worked out of the USGS office in Menlo Park, California, so each year we’d pack the truck for the 1000-mile drive out to northwest Wyoming.  Between 2003 and 2015, we planned an annual fall excursion to visit a series of thermal features around the park.  Occasionally we’d revisit old favorites to provide an understanding of temporal variability of gas compositions at springs and fumaroles (steam vents).  More often, we’d seek out new areas to explore.  Usually, we’d plan our work with other USGS researchers, with student assistants, or with university colleagues who collaborated on some aspect of our work. Some years we organized expeditions with as many as eight people, and other years we’d be slimmed down to two or three.

Laura Clor and Jonathan King sample gas bubbles at Fern Lake. Photo by Jake Lowenstern, USGS.

Fresh silica terraces form in the outflow of a pool on Porcelain Terrace at the Norris Geyser Basin. Photo by Jake Lowenstern, USGS.

Mudpot near Pelican Creek. Photo by Jake Lowenstern, USGS.

Camping: On a typical trip, we’d arrange for a “drop camp,” where horses and mules (and on one occasion, a boat) would transport our gear into a backcountry campsite that we’d use as a base of operations.  We’d arrange for 6 to 10 mules to carry our 300-400 kg of gear. Besides our food and camping equipment, the outfitters would transport sampling equipment (gas bottles, tubing, meters, and solutions), a gaging rod, and flux meters and accumulation chambers used to estimate gas emissions from the ground.  We needed batteries, computers, solar panels, and other materials to keep us productive for up to six days.  The outfitters would meet us on the first day and would migrate all our equipment into panniers, Pelican cases, Action Packers, and other creative means for strapping gear onto a mule.  Typically, we’d walk to the site, anywhere from 7 to 16 miles from the trailhead, and find our gear waiting for us at the backcountry campsite. A typical Yellowstone campsite contains a fire ring, an outhouse, and one or more horizontal “bear” poles for hanging food.  Each day we’d wake at dawn, eat a quick breakfast, and hike for up to two hours to reach our worksite.  If we were lucky, we’d be back to camp in time to cook dinner, and re-hang the food before it got too dark to see.  When we collected waters during the day, we’d usually have to do a “campsite titration” to determine alkalinity (dissolved bicarbonate).  Almost always this wouldn’t happen until after dark, requiring us to use headlamps to read our notebooks and operate the equipment.  Finally, at the end of the trip, the pack train would return to transport our gear back to the trailhead and our vehicles.

Campsite at Heart Lake. Photo by Shaul Hurwitz, USGS.

The pack train passes us on the Wapiti Lake Trail on our way to the campsite. Photo by Jake Lowenstern, USGS.

Nature: What can I say about Yellowstone that hasn’t been already said?  Yellowstone is different in so many ways.  It’s a high plateau full of broad meadows, swamps, forested glens, acid barrens, and sweetly flowing streams. There are animals everywhere. It’s hard to spend a day on the trail without spotting an elk, a bison, or a coyote.  Less frequent but still common are bears, wolves, moose, pronghorn, badger, skunk, porcupine, snakes, and many others.  Every day provides an interesting insect, frog, or bird to observe.  Of course, there is also an incredible diversity of thermal features to visit, with ranges of temperatures, acidity, chemistry, and local geology that create infinite variations.

Photosynthetic thermophile lifeforms impart a green shade to this streambed at the West Astringent Creek thermal area. Photo by Jake Lowenstern, USGS.

The ground cover at Forest Springs turns color in early fall. Photo by Jake Lowenstern, USGS.

Favorite Places: Each trip was so distinct.  Shoshone Geyser Basin is reminiscent of the Upper and Lower Geyser Basins (where Old Faithful resides), with numerous geysers and castles of silica sinter.  Hot Springs Basin is an enormous, remote wasteland of acid soils and muddy flats.  Glen Africa Basin is an unexpected garden of flower-lined hot springs rushing out of the base of the Central Plateau lavas.  Brimstone Basin is a broad expanse of cold, gassy soil; the remnants of hot ground in earlier times.  The eastern part of Yellowstone hosts a whole series of remote locations with fun surprises: West Astringent Creek, Mushpots, Broad Creek, Pelican Creek, and Josephs Coats.  Turbid Lake is a relatively accessible site and the location of a giant hydrothermal crater formed by a steam explosion around 10,000 years ago. Washburn Hot Springs looks like many other acid sulfate regions at Yellowstone but is rich in gases like ammonia and methane from the breakdown of organic material in buried sedimentary rocks.

Hot pools along Shoshone Creek in the Shoshone Geyser Basin. Photo by Jake Lowenstern, USGS.

Flowers carpet the ground along Upper Alum Creek, Glen Africa Basin. Photo by William Snow.

Dried sulfur flows (black) cover the acid-altered terrain of the Brimstone Basin. Photo by Jake Lowenstern, USGS.

Safety: Although backcountry trips have the potential of being interrupted by accidents, fortunately, I can state that no one in our group ever suffered anything worse than a twisted ankle.  In thermal areas, we exercise extreme caution and require that members of our group always wear long pants, leather hiking boots, and knee-high waterproof gaiters.  The latter prevent infiltration of boiling water down into the sock if you break through the surface and sink into searing mud and water.  People can end up with serious burns if they don’t take this simple precaution.  A safety plan is part of the normal process to obtain a research permit from the National Park Service.  Anyone seeking to collect samples or do science at Yellowstone submits a proposal that undergoes peer-review and oversight from the park research committee.  It’s an important step to protect fragile park resources and to ensure the safety of visitors to the Yellowstone backcountry.

One continuing frustration was that despite our careful planning, sometimes nature wasn’t obliging.  Forest fires and aggressive bears interfered with our plans on multiple occasions.  Twice we had to cancel trips to Highland Hot Springs due to aggressive bears frequenting the trails in that region.  In 2012 we reached our goal but had to approach the area from the west, which required many more miles of driving (and cost) to get the mules to the trailhead.

A grizzly bear strolls through a spring snow flurry. Photo by Heather Bleick, USGS.

Bison graze in Yellowstone’s Lower Geyser Basin. Photo by Jake Lowenstern, USGS.

Weather: For the most part, August and September provide plenty of warm, clear weather that is outstanding for exploration and enlightenment.  Nevertheless, we probably experienced every kind of weather possible during our trips across the park.  We camped in the snow at Smokejumper Hot Springs, hiked through a hail storm at Amphitheater Springs, baked in the hot sun at Hot Springs Basin, and walked hours in the rain at… well, a lot of places.  One year we hiked into Yellowstone Lake’s Southeast Arm, but our gear carried in by boat, couldn’t reach the campsite due to windy weather, whitecaps, and resulting perilous conditions on the lake.  Park hydrologist Dan Mahony waited out the weather in a nearby cove until the weather cleared enough for him to bring us our gear.  For a few hours, we were wondering if we’d have to sleep without our tents and sleeping bags!

Fresh snow in northern Yellowstone. Photo by Jake Lowenstern, USGS.

The Gallatin Range towers above Norris Geyser Basin. Photo by Jake Lowenstern, USGS.

Lessons learned: So, what have we learned?  Over the past 15 years, we’ve published about 15 journal articles on our findings.  We’ve estimated the heat output from Yellowstone with our colleagues Greg Vaughan and Shaul Hurwitz.  We’ve written about the river chemistry with Blaine McCleskey.  Bill Evans and John King explored the geologic record as recorded in tree rings, and Jen Lewicki and Peter Kelly are now using new technologies to look at variations in gas output and chemistry as a function of time.  Deb and I focused mostly on the chemistry and isotopic characteristic of the gases.  We’ve observed that all gases at Yellowstone reflect mixing of magmatic, crustal and atmospheric sources, and that each gas species may be derived from a different source.  That is, most argon and nitrogen are coming from atmosphere dissolved in recharging groundwater.  Carbon dioxide is dominantly coming from the mantle, and methane is created as sediments are heated and metamorphosed.  Helium can be sourced from the mantle, as at Mud Volcano, which reflects a hotspot signature.  Or radiogenic helium can form by the long-term breakdown of uranium and thorium in the earth’s crust, creating alpha particles (essentially, a helium atom).  Because Yellowstone is underlain by old Archean basement rocks, and because the region has been geologically inactive for almost three billion years, a tremendous amount of radiogenic helium built up over time, and was stored in the cold ancient rocks.  When Yellowstone volcanism started up two million years ago, the rocks were fractured, metamorphosed, and melted, releasing long-stored helium and other gases, a process that continues today.

Early morning steam at the Norris Geyser Basin. Photo by Jake Lowenstern, USGS.

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“Brooke received his BSc in Geology from Birkbeck College, University of London in 2015 after collecting rocks and fossils for most of his life. He is currently a PhD student at Hertford College, University of Oxford where he is studying the co-evolution of early eukaryotes and the earth surface environment with Dr’s Nick Tosca, Stuart Robinson and Rosalie Tostevin.”

When someone brings up the topic of geological fieldwork, it conjures images of spectacular far-flung places, remote in time and space. The last thing you would expect is a large shed on a trading estate. Yet this is exactly where I and my colleague, Dr. Rosalie Tostevin, found ourselves in late May 2017. Not the most glamorous of locations perhaps, but this was made up for by the exciting rocks we had come to study. Also, the shed was located just outside Darwin, Northern Territories, Australia, which definitely counts as far-flung.
We stood in a tin-roofed awning, open on three sides to the warm tropical air, it was autumn here and a ‘cool’ 28 degrees celsius. Thankfully we had arrived after the last dregs of the rainy season and been spared the 100% humidity. On either side benches lined with rollers stretched out, one side already covered by trays of rocks another colleague was working on. Still jet-lagged from the 24+ hour trip, it was confusing to see and hear ibis and other tropical birds and reptiles in place of pigeons and seagulls.

Above: a hundred or so meters of the 3.6km we sampled and log in total.

A small forklift truck rounded the corner and dropped a pallet of trays in front of us. Steen, one of the Northern Territories Geological Survey (NTGS) staff, hopped out and we began loading the heavy metal trays on the roller table, Rosalie pulling them the full length. Each tray contained ten meters of rock, pulled from the ground hundreds of kilometers away by prospectors drilling for resources. In this case, oil and gas, but everything from iron to gold, diamonds and uranium have been found in this region.
As we popped each lid, some having been sealed for decades, there were gasps and exclamations of surprise. We expected nothing but monotonous black shale, the standard form of hydrocarbon-rich rocks. Black shale was abundant, but so to where sediments in all shades of green, red and purple, swirled with patterns and structures. These structures are the fingerprints of ancient environmental processes, in this case, telling the story of changing sea levels and river courses 1.4 billion years ago.

Above, oxic sediments mixed with fragments of slightly older anoxic sediments, probably deposited by a flood or a storm.

We spent 5 days frantically logging and sampling what amounted to 3.6km of sediment. Imagine walking that distance but having to stop every couple of meters to make detailed notes and collect a sample. It was exhausting, especially in the heat, but also incredible and exciting to be reading the story written in such ancient rocks and translating it to share with others. The story in these particular rocks is of some of the most ancient complex cells and how changing environmental conditions may provide the stimulus for the very first diversification of complex life. An inexorable process that once started, led to all the complex organisms inhabiting Earth today, including ourselves.
It wasn’t all work (even though I do love logging sediments!), we took some time to explore Darwin and have a mini tour of the surrounding area. The beaches are beautiful, though most are haunted by crocodiles, sharks and the fantastically venomous Irukandji jellyfish. We took a trip up the Adelaide River to see some of those crocodiles up close. One-eyed Brutus was the king of that stretch of river, and given his size and ferocity, it was easy to see why.
We are going back to Darwin this coming March, and then on to Canberra. I wonder unexpected rocks and wildlife we will find this time? Being a geologist provides me the luxury of travel that would be otherwise impossible, and this is something I never take for granted.

Above: Sunset over the Timor Sea at Mindle Beach, Darwin. One of the perks of working in the tropics

Above, Though sadly, no matter how warm it gets, you can’t go cool off in the water.

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Marissa Betts是一位专注于了解世界各地早寒武世动物群的演博士后研究专家。她在澳大利亚昆士兰州新英格兰大学和中国西安西北大学两地工作。 你可以在Instagram @ 200micron上关注Marissa的冒险故事。

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南澳大利亚内陆的弗林德斯山脉(Flinders Ranges)和中国中部陕西省南部的秦岭山脉,从景观和气候到文化和语言,很难想象这两个地方有什么共同之处。但事实是,如果将历史卷轴翻到5亿年前,这两个地方有更多的共同点:很久以前,秦岭和弗林德斯是近邻,但在随后的几个亿万年间的时间,看似缓慢但却持续构造构造作用将它们两地相隔。

在早寒武世(大约538-514 百万年前)期间,南澳大利亚是更大的大陆冈瓦纳超大陆的一部分,它位于赤道附近温暖的热带地区。 在此期间,大部分主要动物群都出现在地质时间尺度上的一瞬间。 这种生物事件通常被称为寒武纪生物大爆炸,是迄今为止发生的最重要的生物多样性事件,并彻底革新了地球上的生命。 此时出现的许多动物都具有第一个复杂的生物矿化骨架; 各种非常小(通常是毫米)的贝壳,刺,锥,帽和板,这些都是成千上万的这个时代的岩石中发现的。 这些小化石讲述着关于早期动物如何进化的大故事,并且可以用来约束古大陆之间的古地理关系。

来自南澳大利亚的早寒武世小壳化石在中国也有发现

在我博士期间,我从南澳的弗林德斯山脉(Flinders Ranges)研究了多样的,丰富的,有时奇妙的早期寒武纪寒武纪微化石; 观察他们的古生物学并将它们用作测年和对比的生物地层学工具。 我目前在阿米代尔(Armidale)的新英格兰大学(UNE)进行的博士后研究,正在纳入一套不同的早期寒武纪微化石,称为小碳质化石(SCFs)。 SCFs特别重要,因为它们由原始的未矿化角质层组成。 这在化石记录中非常罕见,化石记录以矿化硬质部分为主。 我正在为SCFs和最近在Flinders山脉,加拿大,蒙古西部和中国的寒武纪岩石作业期间收集的壳化石进行聚结和加工材料。

测量南澳大利亚弗林德斯山脉的地层剖面, 照片来自Sarah Jacquet

在弗林德斯山脉的野外工作中享用比利茶, 照片来自Sarah Jacquet

我喜欢对我的研究采取“多管齐下”的方法。 它将化石标志与其他类型的数据(例如岩性和地球化学)相结合,使我们能够真正了解最早期动物生态系统的古生物学和生态学的全貌。 我所生成的数据对于解释早期寒武纪期间各大陆的相对位置也是至关重要的,这使我们更加全面地了解在动物进化关键时期的世界。

在加拿大西北地区麦肯齐山进行野外考察, 照片来自Kelly Dilliard

在蒙古西部的萨拉尼亚戈尔(Salaany Gol), Goby-Altai地区沿着剖面采样

中国由各种时代的大量构造单元组成,这些构造单元已漂移至全球各地,并最终拼合到当前的构造框架中。 在寒武纪早期,生活在大陆周围浅海的许多动物是各自地区特有的(或原生的)动物,只有少数动物有效地在全球各地散播开来。来自南澳大利亚和中国南方(中国一个离散的构造板块)的小壳化石组合曾有段时间被公认有近缘关系,但是二者重要的差异告诉我们我们二者曾经很接近但并不太接近。

在野外考察期间,蒙古萨拉尼亚戈尔(Salaany Gol)的雪

蒙古塔什尔地区下寒武统灰岩中的磷化壳化石。

然而,来自中国华北的全新数据讲述了一个不同的故事。来自中国(中国科学院南京地质古生物研究所)和澳大利亚(悉尼麦考瑞大学)的同事最近的工作显示,在华北地区发现了原来只在南澳大利亚下寒武统岩石中才发现的壳化石。这些发现非常令人兴奋,并且使我们对这两个古大陆之间的隐秘关系有了进一步的了解。在新英格兰大学工作期间,我也与中国陕西西安西北大学的同事密切合作。我们目前的工作目标是针对贝壳动物群以及来自澳大利亚和中国的小碳质化石,以进一步阐明这些地体之间的演化,生态和构造关系。寒武纪早期演化是一项十分令人兴奋的研究,因为我们研究的对象是一个由系统演化树最根部早期生物组成的新生生态系统。这些化石非常重要,因为它们正在帮助我们回答关于地球在遥远的过去的重大问题,这是动物进化中的一个关键点。寒武纪早期的每一个难题都非常重要,目前的研究显示南澳和中国这两块拼图能够很好地拼合在一起。

在中国南部的云南二街采石场打包澄江化石,照片来自陈飞扬。

在陕西省镇巴县采下寒武统样品,照片来自陈艳龙

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Marissa Betts is a post-doctoral scholar focused on understanding the evolution of early-Cambrian fauna around the world. Marissa splits her time between the University of New England in Queensland, Australia and Northwest University in Xi’an, China. You can follow Marissa’s adventures on Instagram @200micron.

Click here for the Chinese translation.

The Flinders Ranges in outback South Australia, and the Qinling Mountains in the southern Shaanxi Province in central China. From the landscape and climate to the culture and language, it’s difficult to imagine two more different places. But they have a lot more in common than you might think. Especially if we were to wind back the tape of natural history over 500 million years. A very long time ago, this part of China and South Australia were close neighbors, but over subsequent eons, the slow, inevitable chug of the tectonic conveyer belt has driven them far apart.

During the early Cambrian (~538 – 514 million years ago), South Australia was part of a larger landmass called Gondwana, which was positioned in warm tropical latitudes around the equator. During this time, most of the major groups of animals appeared in a geologic instant. Often referred to as the Cambrian Explosion, this bioevent was the most significant animal diversification ever to have occurred, and completely revolutionised life on Earth. Many of the animals that appeared at this time bore the first complex biomineralised skeletons; an assortment of very small (usually millimetric) shells, spines, cones, caps and plates that are often found by the thousands in rocks of this age. These tiny fossils are telling us big stories about how early animals evolved and can be used to constrain the palaeogeographic relationships between ancient landmasses.

Early Cambrian shelly fossils from South Australia that are also found in China.

During my PhD, I worked on the diverse, abundant and sometimes wonderfully weird early Cambrian shelly microfossils from the Flinders Ranges in South Australia; looking at their palaeobiology and applying them as biostratigraphic tools for dating and correlation. My current postdoctoral research at the University of New England (UNE) in Armidale, is incorporating a different suite of very delicate early Cambrian microfossils called small carbonaceous fossils (SCFs). SCFs are particularly important because they are composed of original, unmineralised cuticle. This is exceedingly rare in the fossil record, which is dominated by mineralised hard parts. I am in the process of coalescing and processing material for SCFs and shelly fossils collected during recent fieldwork targeting lower Cambrian rocks in the Flinders Ranges, Canada, western Mongolia and China.

Measuring a stratigraphic section in the Flinders Ranges, South Australia. Photo credit to Sarah Jacquet.

Enjoying a billy tea during fieldwork in the Flinders Ranges. Photo credit to Sarah Jacquet.

I like to take a “multi-pronged” approach to my research. It is the integration of fossil occurrences with other types of data (e.g. lithologic and geochemical) that enable us to really get an idea of the big picture when it comes to the palaeobiology and ecology of the earliest animal ecosystems. Data that I am generating are also fundamental for interpreting the relative position of continents during the early Cambrian, giving us a more complete understanding of the world during a critical time in animal evolution.

Fieldwork in the Mackenzie Mountains, Northwest Territories, Canada. Photo credit to Kelly Dilliard.

Collecting along the section line, Salaany Gol, Goby-Altai area, western Mongolia.

China is made up of a number of tectonic fragments of various ages that have floated around the globe, eventually colliding together into their current configuration. In the early Cambrian, many of the animals living in the shallow seas surrounding the continents were endemic (or native) to their respective regions, and only a few managed to disperse themselves effectively around the globe. Shelly fossil assemblages from South Australia and South China (a discrete tectonic chunk of China) have been known for some time to bear close similarities, but with important differences which tell us that we used to be close, but not too close.

Snow during fieldwork, Salaany Gol, Mongolia.

Phosphatised shelly fossils in lower Cambrian limestone, Taishir area, Mongolia.

However, brand new data from North China (present day north-east China) are telling a different story. Recent work by Chinese (Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences) and Australian (Macquarie University, Sydney) colleagues has revealed shelly fossil species in North China that were previously known only from lower Cambrian rocks in South Australia. These findings are very exciting and are leading to a revised understanding of the cryptic relationship between these two ancient landmasses. While working at UNE, I collaborate closely with colleagues from Northwest University in Xi’an, Shaanxi Province, China. Our current work aims to target shelly fauna, in addition to small carbonaceous fossils from both Australia and China to further elucidate the evolutionary, ecologic and tectonic relationships between these terranes.Working in the early Cambrian is exciting because we are dealing with nascent ecosystems composed of organisms at the very roots of their evolutionary trees. These fossils are incredibly important because they are helping us answer big questions about what the Earth was like deep in the past, at a pivotal point in animal evolution. Each piece of the early Cambrian puzzle is critical, and it seems like pieces from South Australia and China are fitting together very nicely indeed.

Packing up Chengjiang fossils at the quarry in Erjie, Yunnan, South China. Photo credit to Chen Feiyang.

Sampling some lower Cambrian in Zhenba County, Shaanxi Provence, South China. Photo credit to Chen Yanlong.

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Scott Hassler works for the common good at The Wilderness Society, focusing renewable energy, climate adaptation, and wild land protection and restoration, primarily in the Western United States. He continues to research the environmental effects of extremely large meteorite impacts and teaches a bit at UC Berkeley. Possibly too many of his travels, geologic and otherwise, are detailed here.

I’ve gradually been exploring the Colorado Plateau on my summer holidays, generally via long road trips, camping my way throughout the region looking at rocks, hiking, and taking photographs. There are plenty of federal and state lands to visit – national parks, national monuments, state parks, national forests and national conservation areas, to name a few. Generally, I’ve worked my way west from California, which means crossing the Mojave Province:  enough Basin and Range geology for a lifetime. The Mojave has its beauty, but it has never been very attractive to me. There are exceptions; the Alamo Breccia boggles my mind every time I think about it.

The Utah and Arizona portions of the Colorado Plateau expose Precambrian to Paleozoic (Grand Canyon) and lower Mesozoic rocks (Zion, Canyonlands, Arches, Capitol Reef, Escalante-Grand Staircase). This is the archetypical red rock country of the American Southwest. The regional also includes some younger and equally wonderful exceptions (Bryce, Cedar Breaks), exposed on some of the higher subplateaus. There isn’t a lot of younger Mesozoic rock; I presume this reflects erosion as the convergent plate boundary to the west became more robust, both changing the regional gradients and subjecting the area to long periods of subaerial erosion as well as later Basin and Range extensional events.

Capitol Reef National Park

Cedar Breaks National Monument

There are plenty of Cretaceous rocks on the Colorado Plateau, mostly to the east in Colorado and New Mexico. I finally reached this area a few years ago. It’s a nice drive from Albuquerque northwest onto the Plateau, crossing the Rio Grande Rift and working around the Valles Caldera complex. I quickly discovered that in contrast to further west, there was a much greater breadth of archeology to explore.

There are archeological sites all over the Plateau, which indicate episodic human occupation for several thousand years. The location, lifestyle, and populations have changed, seemingly reflecting climate variations, cultural innovations and migration patterns. Most of the Utah and Arizona sites, which occur throughout the stratigraphy, seem relatively small. This could reflect any number of ecological, climatological, and cultural variables, but I get a distinct sense of fewer people, or at minimum people living lighter upon the land.

My most recent trip was a south to north transect which took in several of the major archeological sites on the southwest Plateau:  Chaco Canyon, Ute Mountain/Mesa Verde and Chimney Rock. Chaco Canyon National Historical Park fully earns its designation as a World Heritage Site. The park includes the ruins of at least 11 great houses – large freestanding structures that may have housed 1000s of people between the 9th and 12th centuries. There are also numerous smaller structures, ranging from what appear to be family homes to large kivas. Chaco’s history is controversial. There’s a historical unconformity, as it were, between the time when the area was finally abandoned and the origins of modern Native American groups. There are traditional stories and some archeology connecting the ancient Puebloans – the people who built Chaco[1] – to modern groups including the Hopi and Zuni, but the scientific threads are frayed.

Part of Pueblo de Arroyo Great House, Chaco Canyon National Historical Park

In any event, the great houses reflect several centuries of intermittent occupation and construction, but it’s uncertain if the area was a major population center. Chaco’s occupation and culture are directly tied to climate evolution across the west. Drought equals contraction, wet means expansion. However much it was used, Chaco was a cultural center. The Chacoan road network essentially radiates from the canyon to points at least 60 kilometers distant. There’s interpretation that the great houses served important ceremonial/religious functions. The area also has very cool archeoastronomy sites, which show a sophisticated understanding of solar and lunar rhythms. I was also intrigued to learn that some of the major sites within Chaco and others up to 100 kilometers to the north in Colorado align in an almost true north geographic line. What this means is speculative.

Chaco Canyon is 25 kilometers long, north-northeast to south-southeast west trending, and up to 2 kilometers wide. It’s cut by the incised Chaco Wash, which meanders between flat-lying cliffs of Upper Cretaceous Menefee Formation overlain by Cliff House Sandstone[2], with an alluvial cap. Both formations comprise varying amounts of interbedded sandstone and shale; they represent shoreline facies of the Cretaceous Interior Seaway. The combination gives the drainage steep walls (a thick sandy unit of the basal Cliff House) and a flat floor (Menefee). My geologic guidebook interpreted this as a barrier beach complex; the mesas of Chaco Canyon’s southern margin represent the barrier beach, the canyon per se was the back beach lagoon, and the northern margin was land. I couldn’t really evaluate this in my explorations. There’s been too much lateral erosion and downcutting since the Plateau was uplifted. The strata looked fairly continuous across the canyon; there was no evidence of any significant faulting.

You will have realized by now that Chaco Canyon and its culture are interesting. To explore the area, I drove to most of the great houses (it’s an American national park, after all) and hiked out of or along the canyon to the others. Only a few structures have been excavated and restored; most are ruins, basically curvilinear, room-shaped mounds of rock.

Nonetheless, I noticed two consistent patterns of geologic interest.[3] First, the style of masonry in the great houses changed through time. This has long been recognized by archeologists, who distinguish four types of construction. Basically, the older, bigger great houses are built from plates of thin (cm-scale) beds that are somewhat randomly laid together. This style is followed by two variations of alternating layers of finer and thicker beds, clearly worked to match, creating a more aesthetic structure. Finally, the younger buildings were made from bigger blocks of thicker sandstone, which looked cruder to my eye. Erosion and reconstruction might have biased me somewhat, but these trends seemed clear.

One of the finely worked styles of Chaco masonry, Hungo Pavi Great House, Chaco Canyon National Historical Park

Youngest style of masonry, Klin Kletso Great House, Chaco Canyon National Historical Park

Second, from observation on my hikes, the source material for the great houses was local Cliff House Sandstone. This makes sense, why carry rocks for long distances? The ancient Puebloans did gather far-sourced materials when necessary; the wood used in all the structures is estimated to have been sourced at forests up to hundreds of kilometers distant. In addition, they were great engineers; there are many examples of both carved stairways and ramps that ascend the basal cliff to the thinner units above, connecting to the Chaco road system. The ramps are impressive; they imply piling up thousands of cubic meters of alluvium, and in at least one case, building and installing a wooden ladder/platform complex into a sheer cliff.

I noticed a distinct trend in Cliff House Sandstone as I wandered around (who follows trails?). Once I got above the basal cliff-forming unit, the abundance of exposed bedding changed, qualitatively at least. Above the rim of the Canyon, hiking was fairly easy as there was little thin-bedded sandstone, just abundant siltstone and shale, which made for fairly easy contour walking. In contrast, away from the main Canyon, the density of thin sandstone beds increased, and more scrambling was necessary.

My untutored speculation based on these two observations is that the ancient Puebloans preferred to work with the most easily quarried close by materials. They preferentially removed the thin sandstone beds first, which may explain the lack of these layers along the canyon closest to construction sites. It would have been relatively easy to excavate thin beds by clearing away the softer surrounding fine-grained material, especially if a wetter climactic period[4]. The sandstone blocks of the later great houses would have required actual quarrying to remove and shape. While this trend in architecture could have been for cultural reasons, maybe it was also out of necessity. All the nearby good stuff was used already.

After leaving Chaco Canyon, I visited both Mesa Verde National Park and the Ute Mountain Ute Tribal Park[5], which is just south of Mesa Verde and contiguous with it. Here in Southwestern Colorado, the structures were also built by the ancient Puebloans, but are younger than Chaco Canyon’s great houses. This is interpreted as a climate-driven migration to higher, wetter areas. There are also suggestions that the Puebloans retreated to more defensible sites in the cliffs, perhaps in response to periods of cultural collapse, which of course could have been climate-driven.

Detail of construction, cliff dwelling in Ute Mountain Ute Tribal Park.

Cliff Palace cliff dwelling, Mesa Verde National Park

In both Parks, the stratigraphy includes much thicker cliff-forming sandstones separated by thinner shaley units. The ancient Puebloans took advantage of this, the geology of the Cretaceous Interior Seaway. When building their amazing great houses into recessive ledges within the cliffs, they chose areas that were south-facing for warmth, big enough for building multi-story, tiered structures, and easily accessible to mesa tops, presumably for agriculture[6]. However, they don’t seem to have quarried the local cliff material for their buildings, but to have brought in thinner bedded material, presumably from higher and lower in the stratigraphy.

There are certainly exceptions to the rule of using local material. Aztec Ruins National Monument (not Aztec, but they looked that way to the Spanish in the 17th century) in northernmost New Mexico is between Chaco Canyon and the Mesa Verde complex, both in space and time. Its architecture looks more like earlier Chaco to me. At Aztec, an excavated and restored wall contains multiple layers of a metamorphic greenstone amid the usual thin-bedded sandstone. It’s pretty. This material would have most likely come from many tens of kilometers away, likely to the north in the San Juan Mountains.

Detail of masonry at Aztec Ruins National Monument

My final stop on this archeological transect was in Southern Colorado, at Chimney Rock National Monument. This site is higher in the Cretaceous stratigraphy; Lewis Shale overlain by Pictured Cliffs Sandstone, representing the next transgressive/regressive sequence after the Menefee/Cliff House sequence.

At Chimney Rock, the ruins of a single great house occupy the top of a Pictured Cliffs-capped butte. It’s a high point, in fact the US Forest Service maintained a fire lookout station here (on top of the ruins!) for many years.  The great house is small on the scale of Chaco Canyon, and was built by people who were either part of or were influenced by Chaco culture, based on its design and other archeology.

Chimney Rock National Monument. Great house ruins are on the rounded butte to left. Companion Rock and Chimney Rock at center and right.

Visitors must take a guided tour of the site (it’s both remote and fragile), so I was unable to test my idea about the builders using local materials. The mesa top was also very hot and exposed. I was on the last tour of the day and it was easily 95 F. In any event, the builders again performed an impressive engineering achievement; they both fit the great house into the small footprint of the mesa top and hauled all the building stone uphill from wherever it was quarried.

So, why build a great house on top of a mesa? Chimney Rock and its partner, Companion Rock, both stacks of Pictured Cliff Sandstone, are just to the north of the great house on the mesa top. Viewed from the ruins, they form a prominent notch in the horizon. Here’s the cool part; the full moon rises in the notch at sunset near the day of the Winter Solstice, but only every 18.6 years during the Major Lunar Standstill[7]. Someone – the ancient Puebloans or their antecedents – figured this out. The great house is thus thought to be a ceremonial site which was no doubt a scene of great activity every couple decades. Chimney Rock is still in use by local Native American groups, so don’t plan on coming here for the next Major Lunar Standstill until 2021.

Companion Rock and Chimney Rock; the moon rises in the notch during a Great Lunar Standstill.

I had read about archeoastronomy before coming to Chimney Rock, but seeing the evidence was very dramatic.  It took many years, if not generations, of observation from just the right place to discover Chimney Rock’s unique location. It took untold work to build the great house, and to learn to build great houses using the best materials from across the Cretaceous Interior Seaway. These long-time frames speak to the endurance of the ancient Puebloan culture the depth of its engineering and astronomical knowledge and to overall human fascination with what happens in the sky at night.

[1] “Ancient Puebloans” seems to be the most accepted current term for these people.  They used to be called the Anasazi.

[2] The Cliff House Sandstone is named for the archetypical Cliff House dwelling in Mesa Verde National Park, which is about 160 kilometers north-northwest of Chaco Canyon.

[3] These are of course my observations, I don’t know if they are original, or even accurate.  Any archeologists reading this, please forgive me.

[4] I have certainly done this many times while studying cm-scale meteorite impact deposits within basinal sequences.

[5] UMUTP was stunning.  I took the required day-long guided tour, which was an opportunity to explore several well preserved but unexcavated ruins.  Much more interesting than the huge tours at Mesa Verde.  Highly recommended; make reservations in advance.

[6] There is speculation that these sites were also more defensible; there is clear evidence of horrific cultural collapse at the end of the Chaco culture.

[7] Here’s what I learned about a Major Lunar Standstill.  The moon’s orbit around the Earth oscillates, gradually causing the moon to rise at different points on the horizon. A single oscillation, i.e., N to S to N, takes 18.6 years. The moon seems to pause for about three years at the end of each cycle, rising at more or less the same point on the horizon before beginning to move back in the opposite direction. This pause is the Standstill.

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Lorraine is a postdoctoral researcher at the Swedish Museum of Natural History in Stockholm. She completed a PhD at Lund University, Sweden and a MSc at Rennes 1 University, France. She has a general fascination for mountains, enjoys fieldwork and is thrilled by the sight of high-pressure rocks.

The first time I landed on Swedish bedrock was just a few days after I actually landed for the first time in Sweden. I had just completed a BSc – MSc project on beautiful, ostentatious blueschist outcrops in Greece. In comparison, the soupy, partially molten, complexly folded grey gneisses, hidden in the forest, seemed properly scary at first. My mission as a PhD student was to find out the history of pretty uncommon rocks that managed to remain incognito among these gneisses until they were recently described (Möller, 1998). These rocks, called eclogites, are the witnesses of the making of mountains, the Sveconorwegian orogen, which formed one billion years ago and resulted in a gorgeous succession of outcrops across the now peaceful, smooth and low- lying southern Scandinavia. Eclogites are particularly significant; they represent the deepest section of this Precambrian mountain belt exposed within the Fennoscandian Shield that, in a global framework, was a major part of the Rodinia supercontinent. For my PhD, I was interested in sorting out the sequence of tectonic events (how and why rocks got deformed) and the metamorphic evolution (how deep and how hot the conditions were) in these Sveconorwegian remnants.

Modern vs -nordic- Precambrian orogen. Most Precambrian orogens are deeply eroded, forming dismembered pieces on Earth, but represent a unique chance to visualize the heart of a mountain, unreachable in most Phanerozoic orogens. It is like lifting the lid of a mountain!

Me taking notes on a garnet-amphibolite outcrop.

I spent more than a dozen weeks in the field doing detailed mapping during the first two summer seasons of my PhD. I focused along a strongly deformed area that represents the basal shear zone of the high-pressure nappe. In this highly deformed zone, exhumation-related folds are ubiquitous and the first goal was to better understand by which mechanisms they were transformed. My daily routine was to locate outcrops in the woods (which was sometimes tricky as we can see on the next picture) without getting too distracted by the fascinating fauna or delightful, oversized mushrooms (pictures below).

When I was lucky enough to find a large outcrop with folds or good-looking rocks, a big part of the job was to sit down, draw and try to understand what had happened to cause these localized snapshots of rock-soup.

At first, I would call these outcrops “rock-soup snapshots”, but this one ended up being one of my favorites! Strimma, my PhD supervisor’s dog, for scale.

The local mega-fauna is shy, but you may be watched discreetly by a few moose and I later realized that no one could actually promise that wolves wouldn’t occasionally passively walk by. Anyway, your worst enemy is, by far, nasty-diseases-bearing-ticks who hang out pretty much everywhere so you have to watch out. I figured out relatively late that just sealing yourself with your socks on top of your trousers and your gloves wrapping the sleeves of your rain jacket is a simple, yet effective way to go.

A curious moose

examples of tasty mushrooms

examples of less-tasty colorful mush

Time to unwrap Nature’s gift

Yes, I said, “gloves” and “summer season” earlier. You may wear gloves either from the recalcitrant cold weather in May or for moss gardening purposes because most outcrops are covered with a thick layer of moss that you’ll have to gently peel off the outcrop (picture on the right). Sometimes, hours had to be dedicated to cleaning a new outcrop, although we try to limit our footprint on nature. Cleaning, therefore, has to be strategic, and unlike wild boar, we put back all the moss peels where they come from!

Examples of typical folds in SW Sweden – tight asymmetric folds.

Examples of typical folds in SW Sweden – melt escaping through fold hinges

Examples of typical folds in SW Sweden – extreme stretching in the E-W direction

Examples of typical folds in SW Sweden – just a good looking one 30km west of the study area -bottom right-).

Systematic mapping of small-scale structures is necessary for reconstruction of large-scale ones because they often are identical in style. Planar and linear deformation structures in shear zones can help to figure out the ratio of flattening versus elongation. The geometries and orientations of folds also carry information about kinematics and deformation. In the region, there are 4 main groups of folds, and they can be quite spectacular. At high temperatures, rocks will start to melt in proportions that are largely dependent on the rock’s composition and water content. The interplay between folding, shearing and partial melting lead to the formation of very tight folds, melt expulsion through fold hinges and extreme stretching (examples on the pictures above).

This sketch compiles the main features of the major folding event, with melt gathering expulsed where it could and the extreme east-west stretching. We interpret this fold as formed by intense general shear, with the folds that develop parallel to the main transport direction, because the whole domain was “flowing” and squeezed up towards shallower levels. It is only flowing on a geological time-scale though, in a similar way as hard glaciers are flowing.

It is pretty bold to dare to sample strongly deformed eclogites; here we had to –desperately– ask a former quarry worker, Thore Malmgren, to blow the outcrop (you can see on my face that this has been a long and pretty epic process). Photo credit: C. Möller.

Doing fieldwork always has its good and bad days, especially when you’ve spent too much time swimming in swamps on your own. There is a consensus among the locals and accustomed geologists that I was pretty unlucky with the weather though. I thought I missed a chance to bring colleagues from the ecology department, sure to have discovered a new rainforest. Yet, there is no greater feeling than the one you get when you slowly peel back 10 cm of moss and discover a new eclogite outcrop (pictures below). You then realize that you are probably the first one that has seen them in ages, and quite likely to be the first one to make happy jumps in front of them.

The first sight of a freshly uncovered eclogite outcrop

A pretty mossy outcrop in the forest

The quietness of the colorful Swedish countryside, with lakes, trees, and typical red farms, is very pleasant on sunny days. Outcrops are sparsely distributed within the eclogite-bearing area, but often of decent size and relatively accessible in “normal” weather conditions. Regardless, the sight of gorgeous kyanite eclogites would largely compensate for any effort (pictures below). They typically contain partially preserved large kyanite crystals together with garnet and omphacite and even locally some purple corundum (ruby)!

The classical beautiful kyanite-eclogite

The incredible garnet-floored little harbor near Varberg

We estimated that the eclogites in southern Sweden were buried at a pressure ~18kbar (that would roughly correspond to 60 km of depth), and temperatures of nearly 900 °C. They also record a partial exhumation through ~10 kbar at 850 °C. The pressure and temperature history recorded in the eclogites during their burial show a pretty “sudden” burial event before their exhumation. Because the rocks were not heated further during their travel from depth to near the surface either, we think that this journey – back and forth – was relatively quick. It is uncommon to be able to unravel both the burial and exhumation history of high-pressure rocks because processes get superimposed and tend to obscure rocks’ secrets even more. Besides, it is believed that quick mountain building processes are more common for recent orogens, and it is still unclear how and how differently these hotter mountains were formed 1 billion years ago. Eclogites in southern Sweden, therefore, helped in this perspective, by showing that the Sveconorwegian Orogen may not have been that different from the nowadays Himalayas.

If you are interested in reading more about our recent work on the Sweconorwegian eclogites:

Tual, L., Möller, C., Whitehouse, M., submitted. Tracking the prograde P–T path of Precambrian eclogite using Ti-in- quartz and Zr-in-rutile thermobarometry.

Möller, C. & Andersson, J., 2018. Metamorphic zoning and behaviour of an underthrusting continental plate. Journal of Metamorphic Geology.

Tual, L., Pitra, P. & Möller, C., 2017. P–T evolution of Precambrian eclogite in the Sveconorwegian orogen, SW Sweden. Journal of Metamorphic Geology.

Tual, L., Pinan-Llamas, A. & Möller, C., 2015. High-temperature deformation in the basal shear zone of an eclogite- bearing fold nappe, Sveconorwegian Orogen, Sweden. Precambrian Research, 265, 104-120

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Erin Martin is a PhD student studying at Curtin University in Perth with Professor Bill Collins and Professor Zheng-Xiang Li. Her work employs zircon geochronology and Lu-Hf isotope geochemistry to evaluate plate tectonic processes and paleogeography of the Neoproterozoic, with a focus on the orogens of Argentina and southern Brazil. Read more about her work here.

I recently had my first paper accepted for publication. I am halfway through my PhD and was delighted that one of the first big hurdles of my career had been crossed. As well as receiving congratulations and support from my colleagues and superiors, I was also confronted with a surprising comment. A male Professor saw it fit to impart some wisdom, telling me that “now you have been published as E. L. Martin, you have to keep that same name, otherwise your work will be lost”, following with “You know, so if you get married, your professional name will have to remain the same”.

Initially, I ignored the comment. I’m certain that it wasn’t meant to be controversial, perhaps simply advice of the way things are for a woman in Geology, which has for nearly two centuries been a boys club. However, as the days wore on, this innocuous comment festered in my mind. While the publication-name-change conundrum was something I had considered before, it was absolutely the last thing on my mind whilst I excitedly made the last few edits to my type-set manuscript.

The idea that I as a woman would have to choose between a married name and a professional name frustrated me. If I marry and have a family at some stage, should I risk my previous publications being overlooked or no longer linked to me? Or, should I choose to have a different surname to my possible future husband and children? Should I attempt to juggle two names and have separate home and work versions of myself? Should I attempt the double-barrel surname?

Women in Science face many hurdles. More here.

This is not just an issue faced by women in Geology but in all science disciplines and professional women in general. A good friend of mine was wrestling with the same problem before she got married a few years ago. She is a respected engineer working in the transport sector for state government (also in a male-dominated industry) and had established her name to be synonymous with a reliability and getting things done. She was concerned that the gravity of her name may be lost when people no longer recognised her familiar surname. Additionally, she found it a little awkward, if not unprofessional to add a disclaimer to each of her emails that she was now married and thus her name had changed.

It would be ignorant to suggest that only women are affected by name changes during their careers. But with Gen-X-ers and Millennials marrying later in life, and the number of women taking on careers in science also on the increase, I can’t help but think that the situation I have just encountered will become increasingly common.

So, as any good scientist should, I did some research.

A quick Google search reveals a couple of blog posts that have addressed the topic. One such post on Sciencewomen, from 2009 offers a list of options for an engaged PhD student considering whether she should publish under her married name before she weds. Suggestions include noting on the blogger’s resume and website that her name had changed once married, that it may only be a couple of papers that are published during her PhD before she marries and that the majority of papers that would impact her career would be probably published under her married name.

Commenters seemed to be advocates for hanging on to their maiden name, with or without taking the surname of their husbands. Some using their maiden name as a middle name, others hyphenating. Commenters that argued for not taking a married name often did so from personal experience – one woman had subsequently divorced and so was happy to have retained her maiden name, another mentioned a friend who had married twice, each time adopting the maiden-married name hyphenate and returning to her maiden name between marriages, the resulting chronology of her publications revealing the details of her personal life.

A paper published in the Journal of the American Society for Information Science and Technology in 2011, performed a study aimed at identifying how women who had published under multiple names were identified in indexes and citations (Pellack and Kappmeyer 2011). The literature review of the article highlighted, notably, that there was very little research on the effect of name change on citation rate stating “Even though women’s name changes have the potential to affect a large portion of the population, the way in which indexing services and citation methods deal with this is not well documented”. After investigating over 300 publications of women who had published with multiple names, the authors delivered several recommendations, including, that indexing databases (such as Google Scholar, Web of Science and Scopus) and citations use cross-references for multiple author names. Interestingly the work also recommended that authors should include their former name as part of their new name to allow researchers to find their earlier work, or use self-citations to promote authors previous work under a different name.

Indexing services such as Google Scholar have become significantly more powerful since these articles were written at the turn of the last decade. While I was unable to find Google Scholar policies explaining linking articles for authors with multiple names, I did find that it is extremely easy to change your profile name without your previous work being lost. Many women have taken to listing their profile names as First-name Married-name (maiden name: xxx) with publications from both names linked to their profile. Further, a Google Scholar search of an author with such a profile by either their married name or maiden name yields the same results. Another perk of having a Google Scholar account is that your h-index is automatically calculated based on the work linked to your profile. It should be noted, this is only the case if you have set up a Google Scholar profile.

A Google Scholar search reveals that work published under multiple names is linked the author and contributes to h-index.

Disappointingly, when I carried out the same married name/maiden name search using Scopus I did not get the same result. Instead, the search returned two separate author ID’s, two separate reference lists and two different calculated h-indexes. It seems that Scopus treats a person that has published under two different names as two different people.

Scopus does not group work published by a single author with multiple names. Note the author histories on the right.

Based on my investigations, I have come up with some recommendations to ensure that your body of research is as accessible as possible:

  1. Have an online presence – Create an account on an indexing service (such as Google Scholar or ResearcherID through Web of Science) and moderate your work. If you have a Google Scholar account, for example, you can search for your own work and link it to your profile. This minimizes name change issues and even problems with the various name formats adopted by various journals. A website is another great way to clearly show your work. Your homepage can also be listed on your profile of your preferred indexing service.
  1. Get an Open Researcher and Contributor ID (ORCID) – An ORCID is a unique code assigned to you, used to identify any work that you author without the worry of name ambiguity. This code can be added to your author details whilst submitting papers for publication. Alternatively, post-publication, you can go to the ORCID website and add your work to your ORCID. Scopus and Web of Science use ORCID’s as an additional author identifier, and RearcherID links directly with ORCID to ensure your author profile is up to date.
  1. Take whatever name you want – The more I read on this topic, the more I find that the concept of a ‘family name’ is evolving with time and varies with culture. In many nations, it is traditional for a family to take on the surname of the woman. Some families are happy with every one retaining their surname and giving the kids a hyphenated name. I have also read a fantastic article in The Guardian by a woman whose family adopted a completely new surname for their clan. The truth of the matter is, names change. Luckily we have the resources available for our work to never be lost, regardless of the name we choose to tag it with.

Further Reading and Resources:

Feature image: https://domesticsciences.wordpress.com/

Sciencewomen Blog: http://scienceblogs.com/sciencewoman/2009/06/12/ask-sciencewomen-what-name-sho/

If not my surname or my husband’s, could we call our child after a New Zealand volcano? https://www.theguardian.com/lifeandstyle/2017/may/20/if-not-my-surname-or-my-husbands-could-we-call-our-child-after-a-new-zealand-volcano?CMP=share_btn_tw

Pellack, L. J. and L. O. Kappmeyer (2011). “The ripple effect of women’s name changes in indexing, citation, and authority control.” Journal of the Association for Information Science and Technology 62(3): 440-448.

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Jesse Walters recently received a MS from Boise State University where he worked with Dr. Matthew Kohn on a NSF funded project studying Himalayan tectonics. He is currently a PhD student at the University of Maine, and studies sulfur isotope systematics during subduction.

We are all taught the scientific method at some point: a formulaic approach to inquiry we must follow. However, in practice, science is rarely straightforward. Sometimes investigation is required to develop a hypothesis, especially when boundaries are being pushed. Alternatively, well-formulated hypotheses may need to be abandoned because the methods to test it are insufficient. My project, a 3-year investigation of the tectonic evolution of the Himalaya in the Annapurna region of central Nepal, is a tale both of research in one of the most dynamic, beautiful places on Earth and of making life’s lemons into lemonade.

The 7,937-m peak of Annapurna II, the 16th highest in the world, photographed from the steps of a monastery in Pisang.

A fascinating feature of the Himalaya is the apparent lateral continuity of the major lithotectonic units and major structures. The Himalaya are largely comprised of metamorphosed sediments deposited along the northern margin of India. The Indo-Euasian collision 50–55 million years ago initiated cycles of burial and uplift that built the fascinating tectonic sandwich of mountains we see today: hot, deeply buried rocks in the central region of the mountains bounded to the north and south by cooler, more shallowly buried rocks.
The construction of the hot “crystalline core” of the Himalaya remains an area of intense debate. One scenario employs a tectonic meat slicer: as India is thrust beneath Eurasia, slices of India become attached to the overriding plate, and the bounding fault shifts to a lower position. Another scenario (called “channel flow”) suggests that the deep, partially molten rocks beneath the Himalaya, heated by radioactive decay, ooze to the surface to take the place of rocks removed by erosion. A channel of rock flowing to the surface requires the overlying rock to move in the opposite direction, which has been used to explain the presence of the large-scale, normal-sense shear zone that overlies the crystalline core. Rocks flow at an extremely slow rate, and for channel flow to work, this normal-sense shear zone must have been long-lived. However, the duration of this structure (referred to as the “South Tibetan Detachment”) remains poorly constrained.

Layers of calc-silicate (green) and psammitic (gray) gneisses cut by granite dikes. Titanite is a common accessory mineral in calc-silicates.

We hypothesized that the South Tibetan Detachment in the Marsyandi Valley was active over the same period as the thrust marks the lower bound of the crystalline rocks (a requirement of channel flow). The goal was to constrain the duration of movement on the structure by identifying the duration of high temperature (700-800 °C was expected for these rocks) metamorphism on either side of the shear zone. The technique employs chemical and isotopic analyses of the mineral titanite (CaTiSiO5). Titanite uniquely incorporates trace amounts of uranium and zirconium. The radioactive decay of uranium to lead at a specific rate allows the calculation of a mineral’s age, while the substitution of zirconium for titanium is indicative of temperature. Assuming new titanite was growing throughout metamorphism, we can analyze this mineral to track how temperature changes through time. For a normal-sense shear zone like the South Tibetan Detachment, we would expect that the overlying rocks are heated as the underlying rocks cool.

The road that leads up the Marsyandi Valley. Recently built, the locals say the road will eventually connect with the Kali Gandaki Valley, making the entire Annapurna circuit accessible to vehicles.

The plan was simple: drive up the newly built road in the Marsyandi Valley to the town of Chame, trek farther up the valley to sample above the detachment, and then drive up the Kali Gandaki Valley and do the same. I collected samples during April 2014, and the next 2 years involved processing samples, calculating ages, and determining metamorphic temperatures.

A view of the Marsyandi Valley upstream of the town of Chame. The South Tibetan Detachment is located somewhere in this image; however, we were unable to locate a clear shear zone in any of the accessible parts of the valley.

Despite not locating the shear zone in the field (a common problem in the Himalaya due to terrain), metamorphic temperatures were found to drop rapidly over just a few hundred meters in the region where the South Tibetan Detachment had previously been mapped. A large-scale structure is required to juxtapose rocks with such different histories. Unfortunately, the rocks above the main strand were too cold to form titanite. Thus, I could only determine the temperature-time histories for rocks beneath the shear zone.
My manuscript, published in the October 2017 issue of the Journal of Metamorphic Geology*, focused on a thrust-sense shear zone that the titanite data revealed a few kilometers structurally below the detachment. This shear zone was active from ~ 25 to 16–17 million years ago. Over the last 10 years, numerous thrust-sense shear zones have been found within the crystalline core of the Himalaya. They suggest that the crystalline rocks were not a single, large, high-grade tectonic unit but a series of two or more smaller slices. However, hope was not lost for the South Tibetan Detachment. The rocks immediately beneath the detachment only showed minor amounts of the cooling: there was no evidence of the large cooling event that would result from the juxtaposition of 530 °C rocks over ~ 800 °C rocks. Therefore, the vast majority of movement along the detachment did not occur until 16–17 million years ago or later.

Looking downriver from Pisang is a large glacially carved wall of banded biotite marbles that sit atop the high-temperature crystalline rocks.

My research took an unusual course, I was still able to tell a story. Yet only half the story was what I set out to find. In science, it is not uncommon that we stumble across new discoveries by happenstance. There is nothing you can do if you cannot find the outcrop you need because it is somewhere up a 1,000-m cliff. With a bit more digging, and perhaps some adjustments to your approach, there may still be something useful to be said. Finally, if there is one piece of advice I would give, it would be to never hold your hypotheses too closely.

Looking up river from near the town of Pisang; above this point the rocks are weakly metamorphosed to unmetamorphosed. It was clear that these rocks would not contain titanite, and this was the farthest point that any samples were collected.

* Walters, JB, Kohn, MJ, 2017. Protracted Thrusting and Late Rapid Cooling of the Greater Himalayan Sequence, Annapurna Himalaya, Central Nepal: Insights from Titanite Petrochronology. Journal of Metamorphic Geology, 35, 897-917.

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