Utah’s Bonneville Salt Flats Has Long Been in Flux

Utah’s Bonneville Salt Flats has long been in flux

February 21, 2024

Salt crusts began forming long after Lake Bonneville disappeared, according to new U research that relied on pollen to date playa in western Utah.


Jeremiah Berneau. Credit: Chevron

It has been long assumed that Utah’s Bonneville Salt Flats was formed as its ancient namesake lake dried up 13,000 years ago. But new research from the University of Utah has gutted that narrative, determining these crusts did not form until several thousand years after Lake Bonneville disappeared, which could have important implications for managing this feature that has been shrinking for decades to the dismay of the racing community and others who revere the saline pan 100 miles west of Salt Lake City.

This salt playa, spreading across 40 square miles of the Great Basin Desert, perfectly level and white, has served as a stage for land-speed records and a backdrop for memorable scenes in numerous films, including “Buckaroo Banzai” and “Pirates of the Caribbean.”

Relying on radiocarbon analysis of pollen found in salt cores, the study, published Friday in the journal Quaternary Research, concludes the salt began accumulating between 5,400 and 3,500 years ago, demonstrating how this geological feature is not a permanent fixture on the landscape.

“This now gives us a record of how the Bonneville Salt Flats landscape responds to environmental change. Originally, we thought this salt had formed here right after Lake Bonneville and it was a static landscape in the past 10,000 years,” said the study’s lead author, Jeremiah Bernau, a former U graduate student in geology. “This data shows us that that’s not the case, that during a very dry period in the past 10,000 years, we actually saw a lot of erosion and then the accumulation of gypsum sand. And as the climate was becoming cooler and wetter, then the salt began to accumulate.”

Read the full story by Brian Maffly in @The U

ACCESS Story: Sarah Lambart

'ACCESS'ing Geology & Geophysics

ACCESS Scholars faculty liaison, Sarah Lambart, initially got involved in the program because she wanted to host students in her lab. An Assistant Professor in Geology & Geophysics at the University of Utah, Lambart wanted to offer hands-on activity in small research projects that students could actually work on during the semester. "I really liked working with ACCESS students. [They are] very smart ... very enthusiastic, very curious about learning new things, and so when they created this faculty liaison position, it's something I knew I would be interested [in].”

As principal investigator (PI) of the MagMaX Lab, recent projects have included working of the cause of excess magmatism during the Northeast Atlantic breakup (IDOP Expedition 396), magma genesis and transport, quantifying the mantle heterogeneity and the implications for the Earth dynamics, and, more recently, better understand the formation of critical minerals and ore deposits. If this sounds like an intense program focused on the chemistry of Earth and planetary interiors, it clearly is, especially with her emphasis on the role of magmatic processes during the differentiation and chemical evolution of terrestrial planets. "I use experimental devices such as piston-cylinders and one atmosphere furnaces to simulate high pressure-temperature conditions relevant for planetary interiors as well as various analytical techniques. Those highly-specialized techniques are designed to characterize synthesized and natural samples. "Because one limiting aspect of solid-media apparatus is that all experiments are performed in closed-systems," she writes in her research statement, "I also use innovative experimental strategies to investigate new topics." Those strategies include simulation of magma circulation and magma-rock interaction or melt segregation. The lab team also uses thermodynamic modeling to extrapolate the data they collect and/or as support for semi-empirical models.

It's exactly the kind of rigor that an ACCESS Scholar interested in earth sciences can sink their proverbial shovel into or their underwater collection implements from the bottom of the sea. (More on that later.)

But Lambart's mentoring and department-based liaisoning with ACCESS has a very human side as well. “So first, I am a woman," she says about a STEM discipline that historically has been male-centric. "But I was also a first-generation student.." Currently, most of the students in her team are also "first-gen." "I understand what challenges you might have when you don't necessarily know how the system works. I'm also from France, and so when I arrived in the US, I didn't know how the system worked. I think providing this opportunity very early on in ... [a student's] career, in their degree, can actually really make a difference at the end. So that's why I was very happy to contribute to this program.”

As a faculty liaison, Lambart coordinates the summer activities that take place in Geology & Geophysics, meets with a group of students on a monthly basis for mentorship, and serves on the selection committee. She has hosted three ACCESS scholars in her lab to date.

Expedition 396 women scientific team. From left: Sarah Lambart (Petrologist, University of Utah, USA), Weimu Xu (Sedimentologist, University College Dublin, Ireland), Stacy Yaeger (Micropaleontologist, Ball State University, USA), Sayantani Chatterjee (Inorganic Geochemist, Niigata University, Japan), Marialena Christopoulou (Sedimentologist, Northern Illinois University, USA), Natalia Varela (Paleomagnetist, Virginia Tech, USA), and Irina Filina (Physical Properties Specialist, University of Nebraska, USA). (Credit: Sandra Herrmann, IODP JRSO) [Photo ID: exp396_254]. ^^ banner photo above: courtesy of Sarah Lambart.

A native of Rennes, France, Lambart earned her doctorate from Clermont Auvergne University in 2010 followed by work as a postdoctoral research fellow at first Caltech (2010-2013) and Columbia University (2013-2015). She then took an appointment as a visiting assistant professor at UC Davis (2015-2016. In 2017, she became a Marie Skłodowska-Curie Research Fellow at Cardiff University in Wales, before landing at the U in 2018. She first got interested in her current research as a child; she had a picture of a volcano in Costa Rica in her bedroom that she had cut out of a National Geographic magazine. In high school she decided she wanted to pursue her passion for volcanoes through research.

"From our observations of the beauty of the Hawaiian Islands," says Lambart, "to the discovery of submarine volcanic chains (i.e., mid-ocean ridges) by Marie Tharp more than seventy years ago, we know that our planet is shaped by plate tectonics and magmatism. Combining geochemistry, experimental petrology and thermodynamic modeling, my lab produces innovative tools to constrain the role of crustal recycling, one of the motor of plate tectonics, on the nature of the mantle source of magmas." She remarks that, because of familiar models, most people do not know that the interior of the Earth is actually the color green, not red. "Most representations of the interior of the Earth in textbooks show it red to express the high temperature environment. However, the mantle is dominated by a rock called peridotite that is mostly made of olivine and pyroxenes, two green minerals," she says. (Click here for a 3D picture of a peridotite, as part of the U's Geo 3D rock collection.)

Recent research from Lambart's MagMaX lab includes an article by former student Otto Lang MS'21 on a new approach to constrainthe mineralogy of the magma sources. "I was [also] lucky to be involved in a recent publication on recommendation for sharing F.A.I.R (Findable, Accessible, Interoperable and Reusable) geochemical data," she says. Her work has taken Lambart to, literally, the far ends of the planet. Insights from results obtained during IODP Expedition 396, on which Lambart has sailed on, were published in 2023. (IODP is an  international marine research collaboration that explores Earth's history and dynamics using ocean-going research platforms to recover data recorded in seafloor sediments and rocks and to monitor sub seafloor environments.) Finally, a highly anticipated paper is expected soon by Ashley Morris, a doctorate student in Lambart's group who worked on an early Eocene dacitic unit collected during the same expedition.

ACCESS Scholars is about the whole being greater than the some of its research parts. The program's signature is to meld academic work with networking, mentoring and work/life balance, a unique undergraduate amalgam in which creativity is paired with analytical inquiry and where experiential learning, in all its forms, is at a premium. As an ACCESS faculty liaison in Geology and Geophysics, Sarah Lambart is no exception. "I love hiking and visiting national parks," she says of her life outside the lab. "During my professional training, I had to cross the country twice. My husband and I used this opportunity to visit as many national parks we could. So far, we visited 32, many multiple times! And I’m sure we will continue to explore new parks in the future."

Sporting an adventurous ethic—from the Atlantic seafloor to 32 of the likes of Yosemite National Park—Sarah Lambart is poised to mentor future Earth scientists at the U.

By David Pace and Seth Harper

New Tyrannosaurus Species

Scientists Conclude New Mexico Fossil Is New Tyrannosaurus Species



Scientists reassessing a partial skull first unearthed in 1983 in southeastern New Mexico have concluded that the fossil represents a new species of Tyrannosaurus - the fearsome apex predator from western North America at the twilight of the dinosaur age - that predated the fabulously famous T. rex.

^ Mark Loewen. ^^ Banner image above: An artist's reconstruction of the newly identified dinosaur species Tyrannosaurus mcraeensis, based on a partial skull fossil collected in New Mexico, U.S. Sergei Krasinski/Handout via REUTERS

Subtle differences from Tyrannosaurus rex observed in the skull merit recognizing the dinosaur as a separate species called Tyrannosaurus mcraeensis that lived several million years before T. rex and was comparable in size, the researchers said on Thursday. The skull previously was identified as a T. rex.

Other researchers expressed doubt that it represents a new Tyrannosaurus species, saying differences between it and other T. rex skulls were unremarkable and the study's conclusion that the fossil dated to 71-73 million years ago was problematic.

T. rex has been the sole species of the genus Tyrannosaurus recognized since the dinosaur was first described in 1905. A genus is a broader grouping of related organisms than a species. T. rex fossils date to the couple million years before an asteroid struck Earth 66 million years ago, dooming the dinosaurs.

The first parts of the New Mexico skull were found near the base of Kettle Top Butte in 1983, with more later discovered.

Paleontologist Anthony Fiorillo, executive director of the New Mexico Museum of Natural History & Science and one of the authors of the study published in the journal Scientific Reports, said about 25% of the skull has been collected. Most of the braincase and the upper jaws are missing.

"Compared to T. rex, the lower jaw is shallower and more curved towards the back. The blunt hornlets above the eyes are lower than in T. rex," said paleontologist Nick Longrich of the University of Bath in England, another of the researchers.

"It's the nature of species that the differences tend to be subtle. The key thing is they're consistent. We looked at lots of different T. rex, and our animal was consistently different from every known T. rex, in every bone," Longrich added.

Vertebrate paleontologist Mark Loewen, associate professor lecturer, Department of Geology and Geophysics, University of Utah is a co-author of the paper and Resident Research Associate at the Natural History Museum of Utah.

Read the entire story by Will Dunham (Reuters) in USA Today.

Kona Coffee Lawsuit

Kona Coffee Claims GET Litigated

On the volcanic slopes of Hawaii’s Big Island, hundreds of farmers in the Kona region produce one of the most expensive coffees in the world.

James Ehleringer

Those farmers recently won a series of settlements — totaling more than $41 million — after a nearly five-year legal battle with distributors and retailers that were accused of using the Kona name in a misleading way.

In 2019, Bruce Corker, who owns the Rancho Aloha coffee farm in the Kona district, filed a lawsuit on behalf of Kona farmers against more than 20 companies. At the center of the complaint was a chemical analysis performed at a private lab in Salt Lake City by James Ehleringer, Distinguished Professor in the School of Biological Sciences at the University of Utah who ran the analysis and who said that standard tests depended on the amount of water in each sample. That wouldn’t have worked on the variety of Kona products at issue.

“As you go from green beans to roasted beans, you’re changing the water content,” says Ehleringer. So he borrowed an approach from geology that instead looked at the relative concentrations of rare, inorganic minerals in the beans. These ratios, he said, stay constant even at roasting temperatures.

After testing coffee samples from around the world as well as more than 150 samples from Kona farms, Dr. Ehleringer’s team identified several element ratios — strontium to zinc, for example, and barium to nickel — that distinguished Kona from non-Kona samples. “We were able to establish a fingerprint for Kona,” said Dr. Ehleringer, who described the general method in a 2020 study. “It’s the characteristics of the volcanic rock.”

Those chemical signatures, he found, were largely absent from samples of coffee labeled “Kona” sold by the defendants.



Read the full article in the New York Times by Virgina Hughes here.

Remembering Geologist Hellmut Doelling

Geology alumnus and generous donor, Hellmut Hans Doelling, worked as a core laboratory curator, draftsman, and assistant geologist with the Utah Geological and Mineral Survey (UGMS) before returning to the U to earn his PhD in geology. 

He was born on 25 July 1930 in Richmond Hill, Queensborough, New York City, the only son of Otto Johannes Doelling and Emma Camilla Hartmann.  The family moved to Salt Lake City in 1943 and crossed “the plains” on a Greyhound bus in 5 days due to a 35 mph speed limit during WWII.

Doelling graduated from West High School in 1948, lettering in track and field. He attended the U from 1948 to 1950, then received a letter from Harry Truman and served in the U.S. Army from 1951 to 1953 during the Korean War, returning to the U in 1953 where he graduated with a B.S. in Geology. He was then called on a mission for the Church of Jesus Christ of Latter-day Saint to the East German Mission, where he served in Neumünster, Brake/Weser, Uelzen, and Berlin, under Presidents Gregory and Robbins. Work experiences up to this time included fruit picker, farmhand, paper delivery boy, newspaper inserter, copy boy, and photo lab assistant (Salt Lake Telegram and Tribune).

After earning his PhD, Doelling first taught at Midwestern University in Wichita Falls, Texas, 1964 to 1966, keeping ties with the UGMS in the summertime and was later recruited as the first chief of the Energy and Minerals Section. In 1983 he became the first chief of the Geologic Mapping program, a position he held until 1995. He then continued as a senior geologist until his formal retirement in 2003. 

Highlights of his profession include the publication of more than 200 books, maps, and articles about the geology of Utah. He also served as president of the Utah Geological Association in 1990 and received the Governors Medal for Science and Technology in 1993.  He also did consulting work, mostly in the western states: in Colorado, Nevada, Arizona, Oregon, California, and New Mexico. He also worked in Arkansas, Mexico, and Canada. 

Doelling also did consulting work, mostly in the West. He also worked in Arkansas, Mexico, and Canada. A gifted musician on the accordion, piano, harmonium, and organ, he died 29 November 2023 in Centerville, Utah at the age of 93. He was born  survived by his wife, Gerda and their seven children.

The Doelling Endowed Scholarship  in the U’s Department of Geology & Geophysics, is named in his honor. 

Read Dr. Doelling’s obituary here

Revisiting the Coast Salish Woolly Dog

Revisiting the Coast Salish Woolly Dog

Researchers and Coast Salish people are analyzing a 160-year-old Indigenous dog pelt in the Smithsonian’s collection to pinpoint the origin and sudden disappearance of the culturally significant Coast Salish Woolly Dog.


Chris Stantis. Banner photo above: The reconstructed woolly dog shown at scale with Arctic dogs and spitz breeds in the background to compare scale and appearance; the portrayal does not imply a genetic relationship. Credit: Karen Carr.

Researchers from the Smithsonian’s National Museum of Natural History led a new analysis that sheds light on the ancestry and genetics of woolly dogs, a now extinct breed of dog that was a fixture of Indigenous Coast Salishcommunities in the Pacific Northwest for millennia. A team of researchers analyzed genetic clues preserved in the pelt of “Mutton,” the only known woolly dog fleece in the world, to pinpoint the genes responsible for their highly sought-after woolly fur.

The study’s findings, published Dec. 14, in the journal Science, include interviews contributed by several Coast Salish co-authors, including Elders, Knowledge Keepers and Master Weavers, who provided crucial context about the role woolly dogs played in Coast Salish society.

“This was one of the most exciting projects in my career as an archeologist and an isotopes expert because of the way that we were able to weave together these different types of knowledge,” said Chris Stantis, postdoctoral researcher in the Department of Geology & Geophysics at the University of Utah and co-author of the study.  “To work with geneticists, historians, and Indigenous Knowledge Keepers just makes better research to bring it all together.”

Read the full article by Lisa Potter in @TheU. 

CO2 changes over past 66 M years

CO2 Atmospheric changes

Carbon dioxide has not been as high as today's concentrations in 14 million years thanks to fossil fuel emissions now warming the planet.


Gabriel Bowen

Today atmospheric carbon dioxide is at its highest level in at least several million years thanks to widespread combustion of fossil fuels by humans over the past couple centuries.

But where does 419 parts per million (ppm) — the current concentration of the greenhouse gas in the atmosphere—fit in Earth’s history?

That’s a question an international community of scientists, featuring key contributions by University of Utah geologists, is sorting out by examining a plethora of markers in the geologic record that offer clues about the contents of ancient atmospheres. Their initial study was published this week in the journal Science, reconstructing CO2 concentrations going back through the Cenozoic, the era that began with the demise dinosaurs and rise of mammals 66 million years ago.

Glaciers contain air bubbles, providing scientists direct evidence of CO2 levels going back 800,000 years, according to U geology professor Gabe Bowen, one of the study’s corresponding authors. But this record does not extend very deep into the geological past.

“Once you lose the ice cores, you lose direct evidence. You no longer have samples of atmospheric gas that you can analyze,” Bowen said. “So you have to rely on indirect evidence, what we call proxies. And those proxies are tough to work with because they are indirect.”

Read the full article by Brian Maffly in @TheU.
Read more about Gabe Bowen, recipient of the College of Science's Excellence in Research award,  and his work with isotopes here.

Read related article "'Call to Action': CO2 Now at Levels Not Seen in 14 Million Years" in Common Dreams.

Remembering Marta Weeks

Remembering Marta Weeks


With husband Karelton Wulf.

A longtime Associate Trustee of the Association of American Petroleum Engineers Foundation she embodied legendary civic promotion as well as historic philanthropic support to the Foundation as well as to the Department of Geology & Geophysics and the College of Mines & Earth Sciences at the University of Utah which honored her in 2010 with the Founder's Day Distinguished Alumna Award.

The daughter of a petroleum geologist and the wife and daughter-in-law of world-renowned petroleum geologists, Weeks generously and continuously supported the AAPG Foundation as well as a host of other cultural and humanitarian causes around the world.

Weeks had many careers (often publicly praised as a “Renaissance Woman”) and remained active and passionate about her roles well after the usual retirement age – she was ordained an Episcopal priest in 1992 – directly impacting thousands of lives through her involvement with a host of groups and organizations.

The world knew of her great and lasting work; friends and those close knew that she was, in the words of past Foundation Trustee Chairman William L. Fisher, “as modest as she is generous.”

With AAPG, she had been a Foundation Trustee Associate since 1976. For her, philanthropic engagement with AAPG was her opportunity of “giving back,” she said, and it was a lifetime pleasure.

“I give to AAPG to honor my father, my husband and my father-in-law,’ she said, “all of whom were involved in petroleum geology.”

For Weeks, advancing opportunities in education for new generations of geoscientists was an especially significant part of her life.

Her most recent gift to the Foundation was bequeathed just last year – a $5 million annuity that will be distributed through 2029, impacting geoscientists for decades to come.

Indeed, she and her family made many donations to the AAPG Foundation throughout its history, including a $10 million bequest in 2006, the largest gift ever received by AAPG.

A Life of Excellence

Marta Weeks receives AAPG Foundation's inaugural highest honor, the L. Austin Weeks Memorial Medal, at the 2008 Annual Convention & Exhibition in San Antonio, Texas.

Marta Joan Sutton Weeks was born in Buenos Aires, Argentina, where her father Fredrick Sutton worked as a petroleum geologist. She was raised in both North and South America, and petroleum geology was a constant in her life.

Her first job – at age 13, while residing with her family in Maracaibo, Venezuela – came as she started a small popcorn business for the outdoor oil camp moviegoers.

She attended high school in Salt Lake City, Utah before attending Beloit College in Wisconsin, then graduated with a degree in political science from Stanford University.

Her career then started with summers spent teaching English for the Mene Grande Oil Co. and the Centro-Venezolano Americano in Caracas, Venezuela. Again, the oil business was a regular part of her life.

She then married petroleum geologist Lewis Austin Weeks in 1951, who was the son of famed petroleum geologist Lewis Weeks, and subsequently resided with him in Utah, Colorado, California and Maryland before moving to Miami, Fla., in 1967.

In 1988 she returned to graduate school in Austin, Texas, earned a master’s degree in theology and in 1992 was ordained an Episcopal priest. Her ministry included chaplaincies at Jackson Memorial Hospital in Panama, the Bahamas, the American Cathedral in Paris, France, and ultimately the Diocese of Southern Florida.

In 2008 she was the first recipient of the L. Austin Weeks Memorial Medal, intended to recognize “extraordinary philanthropy and service directed to advance the mission of the AAPG Foundation.”

In addition to the geosciences, she was passionate in her support of the University of Miami, where she was an advocate for academics, the arts, health care and research.

A complete listing of all her connections, honors and activities would be exhaustive, but a partial listing includes:

  • Director of Weeks Petroleum Ltd., Omni-Lift Corp. and the Weeks Air Museum
  • University of Miami Board of Trustees (their first woman chairperson, 2007-09)
  • Founding member and president of the Stanford Club of Florida
  • A member of St. Andrew’s Episcopal Church Foundation, board member of the SE Episcopal Foundation and a trustee of Beloit College and Bishop Gray Inns
  • A member of the National Advisory Council-University of Utah and the Order of St. John of Jerusalem (both as a chaplain and a Dame)
  • Supporter of the Center for Sexuality and Religion
  • Her name graces the YMCA building in Miami, a music school building at the University of Miami and the center at the Episcopal Theological Seminary of the Southwest
  • Chairs and scholarships are named for her and exist because of her generosity at numerous schools

And Foundation TAs know very well of her passion for golf and active participation at TA annual meetings – a plethora of stories of her exploits on the links will keep that part of her legacy alive for years to come. In addition to being a legendary philanthropist and woman of vision, she was a friend.

After Lewis Austin Weeks passed in 2005, Marta married Karleton Wulf in 2009. Wulf passed in 2020, and Marta spent her final years residing with her daughter, Leslie Anne Davies, on Jupiter Island.

In addition to her daughter, Marta Weeks is survived by her son, Kermit Austin Weeks; granddaughter, Katie Weeks; and grandsons, Bryce and Cole Davies.

A version of this memorial was first published in American Association of Petroleum Geologists (AAPG)'s Explorer where you can read more about Weeks and her impact on the industry. Watch a video of Week's receiving the AAPG's top honor, the inaugural 2008 L. Austin Weeks Medal.


‘UteQuake’ seismic exhibit goes live


“Although a seismometer’s primary role is to record earthquakes, these very sensitive instruments will detect any ground shaking, regardless of the source, including from rowdy Utes fans in Rice-Eccles Stadium.”

This is how the new webpage of UteQuake introduces itsself as it returns to Rice-Eccles Stadium Saturday when the University of Utah faces No. 22-ranked UCLA for the football teams’ Pac 12 conference opener Saturday, Sept. 22.

During the game, which kicks off at 1:30 p.m., the University of Utah Seismograph Stations’ (UUSS) geoscientists from the Department of Geology & Geophysics will monitor amplitude signals recorded by a seismometer they installed Aug. 30 on the west side of the stadium, then tweet interesting observations during the game.

The idea is to help pump up No. 11-ranked Utes’ game-day excitement, while also promoting the Seismograph Stations’ vital public safety mission to “reduce the risk from earthquakes in Utah through research, education, and public service.” The UUSS operates a regional network of 200 seismographs stretching from the Grand Canyon in Arizona to Yellowstone National Park in Montana.

Tested during the Utes’ season opener against the Florida Gators when record attendance exceeded 53,000, the experiment proved a roaring success. So UteQuake will run for the remainder of the season, according to Jamie Farrell, a research associate professor of geology and geophysics.

During Saturday’s game, Mark Hale, one of the seismic analysts at the UUSS, will be tracking the seismic waveforms in real time, then tweeting analysis of readings at key moments, starting with the Ute players emerging onto the field.

Read the full article by Brian Maffly in @TheU.
Go Utes! 

Photo credit: Utah Athletics


Thumping Thermometer

Thumping Thermometer

Old Faithful

While the crowds swarm around Old Faithful to wait for its next eruption, a little pool just north of Yellowstone National Park’s most famous geyser is quietly showing off its own unique activity, also at more-or-less regular showtimes. Instead of erupting in a towering geyser, though, Doublet Pool cranks up the bass every 20 to 30 minutes by thumping. The water vibrates and the ground shakes.

Doublet Pool’s regular thumping is more than just an interesting tourist attraction. A new study led by University of Utah researchers shows that the interval between episodes of thumping reflects the amount of energy heating the pool at the bottom, as well as in indication of how much heat is being lost through the surface. Doublet Pool, the authors found, is Yellowstone’s thumping thermometer.

“By studying Doublet Pool, we are hoping to gain knowledge on the dynamic hydrothermal processes that can potentially be applied to understand what controls geyser eruptions,” said Fan-Chi Lin, an associate professor in the department of geology and geophysics at the U and a study co-author, “and also less predictable and more hazardous hydrothermal explosions.”

The study is published in Geophysical Research Letters.

Not exactly like a geyser
Doublet Pool is, as the name implies, a pair of hydrothermal pools connected by a small neck. It would fit comfortably in one half of a tennis court. It’s situated on Geyser Hill in Yellowstone National Park, across the Firehole River from the hotels, visitor centers and parking lots that surround Old Faithful.

Fan-Chi Lin

“We knew Doublet Pool thumps every 20-30 minutes,” Lin said, “but there was not much previous knowledge on what controls the variation. In fact, I don’t think many people actually realize the thumping interval varies. People pay more attention to geysers.”

The thumping, Lin said, which lasts about 10 minutes, is caused by bubbles in the plumbing system that feeds water, heated by a magma system beneath Yellowstone, to Doublet Pool. When those bubbles of water vapor reach the cool upper reaches of the hydrothermal conduit, they collapse suddenly. Thump.

A similar process happens in geysers and excites “hydrothermal tremor,” Lin said, but occurs deeper in the hydrothermal system, at depths of about 30-60 ft and ends with the geyser releasing pressure through a narrow opening as an eruption. Doublet Pool does not have a plumbing structure that enables pressure accumulation and hence no eruption occurs. Also, scientific instruments placed in and around the pool aren’t at any risk for being regularly blown out.

So, to better understand how hydrothermal systems work, Lin and his colleagues, including Cheng-Nan Liu, Jamie Farrell and Sin-Mei Wu from the U and collaborators from the University of California, Berkeley and Yellowstone National Park, set up instruments called geophones around Doublet Pool in seven deployments between 2015 and 2021. In winter 2021 and spring 2022, with the permission of the National Park Service, they lowered temperature and water-level sensors into the pool itself. Then they watched, waited and listened.

Like blowing on a pot of pasta
The researchers focused on the silence interval, or the time between periods of thumping. They found that the silence interval varied both year-to-year and also hour-to-hour or day-to-day. Their results suggest that different processes of adding or removing heat to the hydrothermal system are behind the variation.

In November 2016, the silence interval was around 30 minutes. But by September 2018, that interval had been cut in half to around 13 minutes, and by November 2021, the interval was back up to around 20 minutes.

What else was happening on Geyser Hill during those same times? On September 15, 2018, Ear Spring, which is 200 feet (60 m) northwest of Doublet Pool, erupted for the first time since 1957. After the eruption, the water in Doublet Pool boiled.

Yellowstone’s hydrothermal system is like an Instant Pot, building up heat and pressure leading up to eruptions of geysers and other features. The unusual behavior of Ear Spring, Doublet Pool and other features suggests that in 2018 the heat under Geyser Hill may have been turned up more than usual. By 2021, like an Instant Pot on Natural Release, that heat and pressure had subsided and the silence interval at Doublet Pool had recovered.

Thermal "thumping" at Doublet Pool.

The researchers also noticed that silence intervals varied from day to day, and even hour to hour. When they compared the weather conditions with the silence intervals, they found that wind speed over the pools was correlated with the silence interval. When wind speed was higher, the interval was longer. Nature was blowing over the top of Doublet Pool, cooling it off.

The team is still working to understand how the blowing wind at the surface of the pool impacts the heat at the bottom, but it’s clear that the wind removes heat energy from the water, just like blowing over a hot drink–or a pot of pasta about to boil over—cools it off.

Doublet Pool

“Right now, we are treating the pool as one whole system, which means energy taken away from the surface makes it harder for the system to accumulate enough energy to thump,” Lin said. “One possibility is that the pool is actively convecting so the cooling near the surface can affect the bottom of the pool in a relatively short time scale.”

Heat inputs and outputs
Using principles of heat transfer, the authors calculated the amount of heat and the heating rate needed to initiate thumping at Doublet Pool. Think again about blowing on a pot of pasta. You can prevent boiling over if you are removing heat (through blowing) at the same rate the heat is entering the pot.

“And as we know how to calculate the heat being removed from the wind,” Lin said, “we can estimate the heating rate at the base.”

The heating rate for Doublet Pool works out to around 3-7 megawatts of energy. For comparison, Lin said, it would take about 100 household furnaces burning at the same time to heat up Doublet Pool enough to thump. (This is also equivalent to more than $5,000 worth of energy daily, which highlights the potential of geothermal energy.)

Knowing that heating rate, scientists can use the silence interval as a measurement of how much heat is coming into the pool, since more heat means a shorter interval.

“A better understanding of the energy budget,” Lin said, “will also improve our understanding of how much energy from the Yellowstone volcano is released through these hydrothermal features.”

By Paul Gabrielsen, originally published @theU.

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