Earth and Planetary Science
EPS Geophysics

Research Spotlights

An artist’s depiction of NASA’s James Webb Space Telescope, which will peer into the very early years of the universe and the atmospheres of nearby exoplanets. (Image courtesy of NASA’s Goddard Space Flight Center)

Robert Sanders, Media relations|January 25, 2022

NASA’s latest and snazziest mission, the James Webb Space Telescope (JWST), launched on Christmas Day, deployed its 21-foot-wide mirror a mere two weeks ago and reached its orbital destination earlier this week. With a flashy new telescope now nearly a reality, astronomers at the University of California, Berkeley, are chomping at the bit to start observing.

After months of anxiety about whether the $10 billion telescope — 25 years in the making and the successor to the highly successful Hubble Space Telescope — would even survive launch, let alone unfold from its chrysalis into a gold-blinged telescope, these astronomers feel confident enough to plan summertime observations of nearby galaxies and of some of our closest neighbors in the solar system.

“I’m so thankful that it launched and everything appears to be working. I think it’s going to be just incredible,” said Ned Molter, a UC Berkeley doctoral student working with campus astronomer Imke de Pater, who leads one of 13 teams given the chance to make early observations with the JWST. “I speak for many of us to say we’re over the moon about the launch.”

portrait of Dan Weisz
Dan Weisz and his team will observe local star clusters and galaxies using the superb sensitivity of the James Webb Space Telescope.

“What a beautiful Christmas present to have the James Webb Space Telescope launch on Christmas Day,” echoed Dan Weisz, a UC Berkeley associate professor of astronomy who leads another team awarded observing time as part of the “early release science” program. “The whole of 2022 is going to be a Webb extravaganza. The first part of the year we’ll get the telescope up to speed and commissioned, and in early summer and fall we’ll start observing and then publishing a slew of papers about the first results. It is going to be the year of Webb. It’s fantastic.”

After its launch exactly one month ago, on Dec. 25, the JWST began coasting through space to its final destination, a point referred to as L2: a special place in the solar system — a Lagrange point — where the gravitational pull on the telescope by Earth is exactly balanced by the gravitational pull of the sun. The JWST settled into orbit around L2 on Monday, Jan. 24, where it will remain forever, looking outward into the cosmos from the side of Earth that is opposite the sun.

Six-month commissioning

As the telescope transited to that point — 945,000 miles from Earth and four times farther from Earth than the moon — scientists began aligning the primary mirror, which is a cluster of 18 smaller, gold-plated hexagonal mirrors, with the secondary mirror to get the sharpest images possible. Other scientists tested the many instruments onboard to make sure they work properly to record infrared light from objects in space.

This video, issued by NASA on Jan. 24, explains how the James Webb Space Telescope will observe the heavens from its orbit around L2, a point on the side of Earth opposite the sun. (Video courtesy of NASA’s Goddard Space Flight Center)

Following the six-month-long commissioning phase, 13 teams chosen by NASA will take the new telescope for a spin, putting its instruments through their paces by targeting astronomical objects that will be the major focus of scientists during the telescope’s planned 10 years of operation, and probably much longer.

“To have two of the 13 led by people at Berkeley was pretty exceptional,” said de Pater, a Professor of the Graduate School who wrote her proposal in 2017 before her retirement from teaching last year.

Given the JWST’s primary mission to study dim, distant galaxies and faint exoplanets, the observations planned by de Pater and her team of about 50 astronomers may seem out of character: They will turn the telescope on one of the brightest objects in the sky, Jupiter.

portrait of Imke de Pater
Imke de Pater will use the mid-infrared sensitivity of the space telescope to study cloud layers in Jupiter’s atmosphere.

“They (NASA) wanted to get involvement from the astronomy community to see what is feasible, what Webb can do, and really pushing it to the limits,” de Pater said. “We came up with the idea to look at the Jovian system, because Jupiter is extremely bright, but next to Jupiter, you have these really faint rings and some really faint satellites. Moreover, we will look at faint spectral features on Io and Ganymede while they are eclipsed in Jupiter’s shadow, a quite challenging experiment since the two bodies will be very close to Jupiter and invisible at visible wavelengths. We thought it would make a really nice proposal to look at these large differences in brightness.”

During her decades-long career, de Pater has used radio telescopes and optical and infrared telescopes, such as the pair at the W. M. Keck Observatory in Hawai’i and the Hubble Space Telescope, to study the atmospheres of our solar system’s large planets, with particular attention to Jupiter’s large storm, the Great Red Spot; the volcanoes of Jupiter’s moon, Io; the icy surface of another Jovian moon, Ganymede; and Jupiter’s rings. She is particularly eager to take advantage of the JWST’s ability to detect mid-infrared light, which will give her access to different layers of Jupiter’s atmosphere, ones she has not been able to explore using earthbound telescopes.

“We hope to find out more about the dynamics in the Great Red Spot and the aurora over the South Pole, and the chemistry and physics of the troposphere and into the stratosphere,” she said.

portrait of Ned Molter
Doctoral student Ned Molter hopes to observe Jupiter’s moon Io this summer, among the first science observations with the Webb telescope.

Molter, who expects to graduate in August and remain with de Pater as a postdoctoral fellow to work with the JWST, plans to use the telescope’s Aperture Masking Interferometer to study the individual volcanoes on Io. With new mid-infrared data, he hopes to accurately measure the temperatures of the volcanoes, which will allow comparison with volcanoes on Earth.

As a new graduate student back in 2017, he had hoped to write his thesis using JWST observations of Io’s volcanoes, but as the launch date was pushed further and further out, he elected to study the atmospheres of Uranus and Neptune instead.

“We sort of pivoted away from the Io science when Webb was being delayed so much,” Molter laughed. “I had to graduate in a certain amount of time, so I found other projects.”

Galaxy formation and dark matter

Weisz, an associate professor of astronomy, and his team will use their allotted time with the JWST to observe the Milky Way Galaxy and its nearby satellite galaxies. Weisz’s main interest is galaxy formation, and in particular, the role of dark matter — the still mysterious stuff that makes up 85% of the matter in the universe — in galaxy formation.

The Hubble Space Telescope has taken many images of M-92, including this closeup in 2017. A ball of stars called a globular cluster, it orbits our galaxy’s core like a satellite and is one of the brightest globular clusters in the Milky Way. UC Berkeley’s Dan Weisz and his team will track the movement of faint stars in this cluster using the new James Webb Space Telescope. (Image by ESA/Hubble & NASA; Gilles Chapdelaine)

He and his team of about 50 astronomers are focused on three different targets. One is M-92, one of the oldest globular clusters in the Milky Way and one of the most photographed by Hubble. The hope is that the JWST can detect the oldest and faintest stars and thus provide a more precise age for the cluster — previewing what the JWST could do for all of the 100 or so globular clusters in the Milky Way.

Another target is an ultrafaint dwarf galaxy — a satellite of the Milky Way 98,000 light years from Earth — that has surprisingly little normal, visible matter, but instead appears to be mostly dark matter. The JWST should be able to detect the galaxy’s very faint stars and, with data from Hubble, map their motions in 3D, allowing astronomers to precisely weigh the dark matter and plot its distribution, constraining some of the theories of what dark matter may actually be.

Even farther away — 3.26 million light years — is a star-forming galaxy that Weisz hopes will test the resolution of the JWST, and perhaps improve the cosmic distance ladder used to measure the expansion of the universe. All three targets will require exploring the capabilities not only of the telescope, but of the detectors that produce the data.

Jupiter and Great Red Spot
A Hubble Space Telescope image of sunlight (visible wavelengths) reflecting off clouds in Jupiter’s atmosphere. With the Webb telescope’s mid-infrared detectors, Imke de Pater and her team hope to see deeper into the Great Red Spot. (Image courtesy of NASA, ESA, and Mike Wong of UC Berkeley)

“We’re building the software needed to basically take the JWST images and turn them into scientifically useful data products, like radiation fluxes, luminosities of individual stars, and galaxies and star clusters in our Milky Way and nearby universe,” he said. “And then, we’re releasing all the analysis software, the pipelines used to reduce it, the catalogs we’re making — all of that stuff is just going to be made public as soon as we’re done, so the community can immediately take it and apply it to their use observing or use it to plan future proposals.”

While Weisz expects the JWST to help advance his field of galaxy formation in the local universe and refine distance measurements in the cosmos, he predicts the greatest discoveries will be about the very early universe and the conditions on planets around other stars, which were NASA’s primary goals for the JWST. Some key questions about the history of the universe and of life in the universe could be answered in the next few years — all potentially worth the price of the JWST.

“I think Webb has gotten a lot of negative attention because of its $10 billion price tag when it was only supposed to be a couple billion,” Weisz said. “But at the end of the day, you look at this and you say, ‘Boy, if this is now going to last 10, 15 years, and it’s going to open windows onto planets and ancient stars in the early universe and tell us about how we got here, it really is just kind of in line with all the other amazing things that NASA has done.’ You look at it in terms of its discovery potential, and I really think it’s a great value.”


William Boos stands on rocky peak on a sunny day with panoramic views of the Arizona natural landscape stretching out for miles.

William Boos in the mountains of Arizona shortly before the start of the monsoon.
(Photo by Stefan Kraus)

Summer rains in American Southwest are not your typical monsoon

Robert Sanders, Media relations|November 30, 2021

The core of the annual North American monsoon is centered over western Mexico (blue oval) and transports water vapor northward into the southwestern U.S., as illustrated by the arrows. Colors represent average summer rainfall in centimeters/day. (UC Berkeley graphic by William Boos)

The months-long rainy season, or monsoon, that drenches northwestern Mexico each summer, reaching into Arizona and New Mexico and often as far north as Colorado and Northern California, is unlike any monsoon in the world, according to a new analysis by an earth scientist from the University of California, Berkeley.

The so-called North American monsoon is important for delivering water to semi-arid areas of the American Southwest — 50% of Arizona’s and New Mexico’s precipitation comes from monsoon rains between July and September — but in recent years has also fueled wildfires around the West. The northern tail of the monsoon sometimes brings thunderstorms and thousands of lightning strikes to California, igniting wildfires.

The word monsoon conjures images of the monsoons of South Asia, where for several months each summer repeated downpours flood India and Bangladesh. These and other monsoons, such as those in Brazil and across Africa, are generated when intense summer sunlight causes the atmosphere to be heated over the continent more than over the nearby ocean, which draws humid air from the sea and dumps the moisture on land during intense storms.

But detailed supercomputer simulations of North American weather patterns show that the North American monsoon occurs when Mexico’s Sierra Madre Occidental mountains divert the eastward-trending jet stream toward the equator and then upward over the mountain slopes, cooling the moist tropical air from the eastern Pacific until it condenses and falls as rain.

This new understanding of the causes of the North American monsoon will have a major impact on forecasts in the region, said William Boos, UC Berkeley associate professor of earth and planetary science and first author of a paper detailing the findings that appeared last week in the journal Nature. The path of the mid-latitude jet stream, which is predicted to change as a result of global warming, and the warmth of the tropical eastern Pacific Ocean are now seen as more important in determining the monsoon than the temperature difference between land and ocean bordering western Mexico.

“What we’re arguing is that the North American monsoon is not a classic monsoon in terms of its central physics, and so we need to look at a whole different set of scientific processes to predict it, both in short-term weather forecasts and long-term climate projections,” said Boos, who collaborated with Salvatore Pascale of the University of Bologna in Italy.

“The previous thinking was that you need to look at how hot the land is compared to the ocean and the future of the ocean: Is the Pacific going to warm more than the land? If it does, then the monsoon might weaken in coming decades,” he added. “Now, we’re saying, ‘No. Instead, you need to worry about whether the jet stream is going to shift.’ If the ocean does warm more than land, that might give you more water content in the atmosphere to condense as it goes over the mountain, and that might strengthen the monsoon, instead of weaken it.”

This is the only monsoon known to be caused mechanically — by the southward and upward deflection of a jet of air by an obstacle — as opposed to thermally, where less dense air becomes buoyant, rises and draws in air from surrounding areas.

A continent-wide weather pattern

Monsoons, Boos said, are continent-size atmospheric wind patterns that control the climate of large swaths of Earth’s surface and supply water to billions of people. The North American monsoon, for example, is crucial for the hydrology of western Mexico and the southwestern U.S.

Deflection of the eastward jet stream (orange contours) from the midlatitudes toward the equator, where it produces precipitation (blue shading, in units of millimeters/day) as it then ascends over the Sierra Madre mountain range (outlined by magenta contour). All quantities are from observational datasets. This new study used theoretical calculations and atmospheric simulations to test the effect of the Sierra Madre mountains on the monsoon. (UC Berkeley image by William Boos)

But while the North American monsoon has been examined by scientists for over a century, its cause has been presumed similar to that of other monsoons, which have been more thoroughly studied. A typical monsoon results from differential heating of land and water during summer months. While the sea is able to mix below the surface the energy it absorbs from summer sunlight, the land cannot. As a result, the land quickly transfers this energy back to the atmosphere, heating the air and making it rise. As it rises, the pressure drops, the air cools, and the moisture it contains condenses into rain.

Boos wanted to test that scenario, using a global climate computer model that incorporates North American weather patterns, as well as the underlying land topography, with a resolution of about 25 kilometers, a big increase over earlier models that, because of computational limitations, were limited to a resolution of about 100 kilometers. With a 100-kilometer grid pattern, land and weather patterns are averaged over 10,000 square kilometers, smearing out the effects of small mountain ranges like the Sierra Madre.

“The mountains on the west coast of Mexico may seem enormous when you stand next to them as a human being, but on a global scale, they are tiny,” he said. “Computer simulations of Earth’s atmosphere and ocean have historically barely been able to represent these mountains — it’s like trying to look at the details of an actor’s teeth on 1970s television. But our observations of wind and rain patterns have gotten much more high-resolution than in the past. We were able to use similarly high-resolution computer models to examine the detailed structure and dynamics of this monsoon and figure out how it works.”

Boos’ model — which he ran at the National Energy Research Scientific Computing Center at Lawrence Berkeley National Laboratory and was so computationally intensive that it took the equivalent of a laptop running for 1 million hours — is the first to study the effect of the Sierra Madre. He found that if the Sierra Madre were missing, the monsoon would basically evaporate.

William Boos in the mountains of Arizona. (Photo by Stefan Kraus)

“When we got rid of the Sierra Madre, the main part of the intense precipitation maximum that runs about a thousand kilometers up and down the west coast of Mexico and extends into the southwest U.S. just vanished,” he said.

He and Pascale also did a theoretical calculation to quantitatively predict how jet stream winds would change if mountain ranges were put in their path, without applying any sort of heating, and found that the mountains produce stationary waves identical to those observed to occur in the jet stream as it interacts with the Sierra Madre Occidental.

“That helped us isolate the cause. You can do modeling experiments with the supercomputer, but there’s so much going on in the supercomputer simulation you don’t know what the fundamental cause is,” Boos said. “But with this theoretical solution, we could say, ‘Ah, the cause is definitely the mountain blocking the winds, instead of anything to do with water condensation or radiative transfer, et cetera.'”

Boos is exploring in more detail the impact on the monsoon of the Sierra Madre, as well as the Sierra Nevada range in California and the Rocky Mountains, focusing more closely on the effects in Arizona and New Mexico.

“This is really just the first study suggesting that the North American monsoon is so fundamentally linked to the blocking of winds by mountain ranges,” he said. “We certainly need to explore this more observationally, theoretically, and with even higher-resolution models.”

The work was funded by the U.S. Department of Energy (DE-SC0019367).






Flyer text, white on blue and gold background, Basic Science Lights the Way, Conversations on Current Research, When the Earth Shakes


A leading research university atop a seismic fault, Berkeley excels at studying earthquakes and creating early warning tools. What you should know to be informed and prepared.

Watch a recording of the talk given Wednesday, October 13, 2021:

Roland Bürgmann, Garniss H. Curtis Chair of Earth and Planetary Science
Qingkai Kong, Research Scientist, Lawrence Livermore National Laboratory
Sarina Patel, doctoral candidate, Department of Earth and Planetary Science
Moderated by Richard Allen, Interim Dean of Mathematical & Physical Sciences
Full listing of talk series Basic Science Lights the Way, Conversations on Current Research:

west Texas earthquake USGS screenshot

Berkeley Seismological Lab (BSL) and EPS Postdoctoral Researcher Guang Zhai, ASU Professor Manoochehr Shirzaei, and EPS Professor Michael Manga publish a research article which demonstrates the deep seismic effects of shallow wastewater injection from industrial activity in western Texas in the journal Proceedings of the National Academy of Sciences (PNAS): Widespread deep seismicity in the Delaware Basin, Texas, is mainly driven by shallow wastewater injection

photo of collected ostrich shell fragments with handwrittem notation of an alpha numeric code in permanent marker on the shells

Robert Sanders, UC Berkeley Media relations| April 30, 2021

Fragments of ostrich eggshells from the Ysterfontein 1 site near Cape Town, South Africa. Researchers have determined that these eggshells are about 120,000 years old, discarded by early Homo sapiens who lived along the coast and exploiting marine food resources as well as ostrich eggs. The scale bar at lower right is 1 centimeter (0.4 inches). (Photo Elizabeth Niespolo)

Archeologists have learned a lot about our ancestors by rummaging through their garbage piles, which contain evidence of their diet and population levels as the local flora and fauna changed over time.

One common kitchen scrap in Africa — shells of ostrich eggs — is now helping unscramble the mystery of when these changes took place, providing a timeline for some of the earliest Homo sapiens who settled down to utilize marine food resources along the South African coast more than 100,000 years ago.

Geochronologists at the University of California, Berkeley, and the Berkeley Geochronology Center (BGC) have developed a technique that uses these ubiquitous discards to precisely date garbage dumps — politely called middens — that are too old to be dated by radiocarbon or carbon-14 techniques, the standard for materials like bone and wood that are younger than about 50,000 years.

In a paper published this month in the journal Proceedings of the National Academy of Sciences, former UC Berkeley doctoral student Elizabeth Niespolo and geochronologist and BGC and associate director Warren Sharp reported using uranium-thorium dating of ostrich eggshells to establish that a midden outside Cape Town, South Africa, was deposited between 119,900 and 113,100 years ago.

That makes the site, called Ysterfontein 1, the oldest known seashell midden in the world, and implies that early humans were fully adapted to coastal living by about 120,000 years ago. This also establishes that three hominid teeth found at the site are among the oldest Homo sapiens fossils recovered in southern Africa.

The technique is precise enough for the researchers to state convincingly that the 12.5-foot-deep pile of mostly marine shells — mussels, mollusks and limpets — intermixed with animal bones and eggshells may have been deposited over a period of as little as 2,300 years.

The new ages are already revising some of the assumptions archeologists had made about the early Homo sapiens who deposited their garbage at the site, including how their population and foraging strategies changed with changing climate and sea level.

“The reason why this is exciting is that this site wouldn’t have been datable by radiocarbon because it is too old,” Niespolo said, noting that there are a lot more such sites around Africa, in particular the coastal areas of South Africa.

map of coast around Cape Town, South Africa
Ysterfontein 1 (YFT1) is one of many middens along the Cape coast, some from the Middle Stone Age (white dots) and some from the more recent Later Stone Age (orange dots). The new dates for Ysterfontein 1 make it the oldest known midden in the world and helps put it in the context of the other sites as archeologists try to understand how early Homo sapiens lived and changed over the last 120,000 years. (Graphic courtesy of Elizabeth Niespolo)

“Almost all of this sort of site have ostrich eggshells, so now that we have this technique, there is this potential to go and revisit these sites and use this approach to date them more precisely and more accurately, and more importantly, find out if they are the same age as Ysterfontein or older or younger, and what that tells us about foraging and human behavior in the past,” she added.

Because ostrich eggshells are ubiquitous in African middens — the eggs are a rich source of protein, equivalent to about 20 chicken eggs — they have been an attractive target for geochronologists. But applying uranium-thorium dating — also called uranium series — to ostrich shells has been beset by many uncertainties.

“The previous work to date eggshells with uranium series has been really hit and miss, and mostly miss,” Niespolo said.

Precision dating pushed back to 500,000 years ago

Other methods applicable to sites older than 50,000 years, such as luminescence dating, are less precise — often by a factor of 3 or more — and cannot be performed on archival materials available in museums, Sharp said.

Middle Stone Age artifacts from Ysterfontein 1
Middle Stone Age artifacts recovered from the Ysterfontein 1 midden include denticulates, points and red ochre (lower right). (Images courtesy of Richard Klein)

The researchers believe that uranium-thorium dating can provide ages for ostrich eggshells as old as 500,000 years, extending precise dating of middens and other archeological sites approximately 10 times further into the past.

“This is the first published body of data that shows that we can get really coherent results for things well out of radiocarbon range, around 120,000 years ago in this case,” said Sharp, who specializes in using uranium-thorium dating to solve problems in paleoclimate and tectonics as well as archeology. “It is showing that these eggshells maintain their intact uranium-series systems and give reliable ages farther back in time than had been demonstrated before.”

“The new dates on ostrich eggshell and excellent faunal preservation make Ysterfontein 1 the as-yet best dated multi-stratified Middle Stone Age shell midden on the South African west coast,” said co-author Graham Avery, an archeozoologist and retired researcher with the Iziko South African Museum. “Further application of the novel dating method, where ostrich eggshell fragments are available, will strengthen chronological control in nearby Middle Stone Age sites, such as Hoedjiespunt and Sea Harvest, which have similar faunal and lithic assemblages, and others on the southern Cape coast.”

The first human settlements?

Ysterfontein 1 is one of about a dozen shell middens scattered along the western and eastern coasts of Western Cape Province, near Cape Town. Excavated in the early 2000s, it is considered a Middle Stone Age site established around the time that Homo sapiens were developing complex behaviors such as territoriality and intergroup competition, as well as cooperation among non-kin groups. These changes may be due to the fact that these groups were transitioning from hunter-gatherers to settled populations, thanks to stable sources of high-quality protein — shellfish and marine mammals — from the sea.

black and white cross section of the middens, and photos of the pile of marine shells
Photographs of marine shells and a schematic stratigraphy for the Ysterfontein 1 shell midden. The positions of ostrich eggshells used for dating and paleoenvironmental reconstruction are shown as egg symbols in the stratigraphic section. (Graphic courtesy of Elizabeth Niespolo)

Until now, the ages of Middle Stone Age sites like Ysterfontein 1 have been uncertain by about 10%, making comparison among Middle Stone Age sites and with Later Stone Age sites difficult. The new dates, with a precision of about 2% to 3%, place the site in the context of well-documented changes in global climate: it was occupied immediately after the last interglacial period, when sea level was at a high, perhaps 8 meters (26 feet) higher than today. Sea level dropped rapidly during the occupation of the site — the shoreline retreated up to 2 miles during this period — but the accumulation of shells continued steadily, implying that the inhabitants found ways to accommodate the changing distribution of marine food resources to maintain their preferred diet.

The study also shows that the Ysterfontein 1 shell midden accumulated rapidly — perhaps about 1 meter (3 feet) every 1,000 years -— implying that Middle Stone Age people along the southern African coast made extensive use of marine resources, much like people did during the Later Stone Age, and suggesting that effective marine foraging strategies developed early.

For dating, eggshells are better

Ages can be attached to some archeological sites older than 50,000 years through argon-argon (40Ar/39Ar) dating of volcanic ash. But ash isn’t always present. In Africa, however — and before the Holocene, throughout the Middle East and Asia — ostrich eggshells are common. Some sites even contain ostrich eggshell ornaments made by early Homo sapiens.

Elizabeth Niespolo in white lab coat and goggles pipetting under a fume hood
Elizabeth Niespolo, at the time a graduate student in UC Berkeley’s Department of Earth and Planetary Science, separating uranium from thorium in a lab at the Berkeley Geochronology Center. (Photo by Warren Sharp, BGC)

Over the last four years, Sharp and Niespolo, at the time a graduate student in UC Berkeley’s Department of Earth and Planetary Science, conducted a thorough study of ostrich eggshells, including analysis of modern eggshells obtained from an ostrich farm in Solvang, California, and developed a systematic way to avoid the uncertainties of earlier analyses. One key observation was that animals, including ostriches, do not take up and store uranium, even though it is common at parts-per-billion levels in most water. They demonstrated that newly laid ostrich shells contain no uranium, but that it is absorbed after burial in the ground.

The same is true of seashells, but their calcium carbonate structure — a mineral called aragonite — is not as stable when buried in soil as the calcite form of calcium carbonate found in eggshell. Because of this, eggshells retain better the uranium taken up during the first hundred years or so that that they are buried. Bone, consisting mostly of calcium phosphate, has a mineral structure that also does not remain stable in most soil environments nor reliably retains absorbed uranium.

Uranium is ideal for dating because it decays at a constant rate over time to an isotope of thorium that can be measured in minute amounts by mass spectrometry. The ratio of this thorium isotope to the uranium still present tells geochronologists how long the uranium has been sitting in the eggshell.

Uranium-series dating relies on uranium-238, the dominant uranium isotope in nature, which decays to thorium-230. In the protocol developed by Sharp and Niespolo, they used a laser to aerosolize small patches along a cross-section of the shell, and ran the aerosol through a mass spectrometer to determine its composition. They looked for spots high in uranium and not contaminated by a second isotope of thorium, thorium-232, which also invades eggshells after burial, though not as deeply. They collected more material from those areas, dissolved it in acid, and then analyzed it more precisely for uranium-238 and thorium-230 with “solution” mass spectrometry.

cross section through 118,00-year-old eggshell
A cross-section of a fragment of an ancient eggshell from Ysterfontein 1 shows that the eggshell structures are well preserved, even though it was buried about 118,000 years ago. At the center is a pore that served as a pathway for oxygen for the incubating chick. Pitted lines are where the researchers used a laser to ablate portions of the eggshell to track concentrations of uranium and thorium and establish the age. (Image courtesy of Elizabeth Niespolo)

These procedures avoid some of the previous limitations of the technique, giving about the same precision as carbon-14, but over a time range that is 10 times larger.

“The key to this dating technique that we have developed that differs from previous attempts to date ostrich egg shells is the fact that we are explicitly accounting for the fact that ostrich eggshells have no primary uranium in them, so the uranium that we are using to date the eggshells actually comes from the soil pore water and the uranium is being taken up by the eggshells upon deposition,” Niespolo said.

Working with UC Berkeley professor of integrative biology Todd Dawson, Niespolo also analyzed other isotopes in eggshells — stable isotopes of carbon, nitrogen and oxygen — to establish that the climate rapidly became drier and cooler over the period of occupation, consistent with known climate changes at that time.

Niespolo, now a postdoctoral fellow at the California Institute of Technology but soon to be an assistant professor at Princeton University, is working with Sharp to date middens at other sites near Ysterfontein. She also is developing the uranium-series technique to use with other types of eggs, such as those of emus in Australia and rheas in South America, as well as the eggs of now extinct flightless birds, such as the two-meter (6.6-foot) tall Genyornis, which died out some 50,000 years ago in Australia.

The work was supported by the Leakey Foundation, Ann and Gordon Getty Foundation and National Science Foundation (BCS-1727085).


From the search for Earth-like planets to seeking knowledge of past climates on Earth, Berkeley’s early-career faculty in the physical sciences push the boundaries of basic research and teaching in their fields. Join us tomorrow to hear from professors in four MPS departments about how their work lights the way.

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Rising Stars of Berkeley Mathematical and Physical Sciences
Courtney Dressing, Alexander Paulin, Daniel Stolper, Norman Yao, and moderator Frances Hellman
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Robert Sanders, UC Berkeley Media relations| January 4, 2021
A 2019 eruption of Steamboat Geyser in the Norris Geyser Basin of Yellowstone National Park. The geyser’s first documented activity was in 1878, and it has turned off and on sporadically since, once going for 50 years without erupting. In 2018 it reactivated after a three-and-a-half-year hiatus, for reasons that are still unclear. (UC Berkeley photo by Mara Reed)

When Yellowstone National Park’s Steamboat Geyser — which shoots water higher than any active geyser in the world — reawakened in 2018 after three and a half years of dormancy, some speculated that it was a harbinger of possible explosive volcanic eruptions within the surrounding geyser basin. These so-called hydrothermal explosions can hurl mud, sand and rocks into the air and release hot steam, endangering lives; such an explosion on White Island in New Zealand in December 2019 killed 22 people.

A new study by geoscientists who study geysers throws cold water on that idea, finding few indications of underground magma movement that would be a prerequisite to an eruption. The geysers sit just outside the nation’s largest and most dynamic volcanic caldera, but no major eruptions have occurred in the past 70,000 years.

“Hydrothermal explosions — basically hot water exploding because it comes into contact with hot rock — are one of the biggest hazards in Yellowstone,” said Michael Manga, professor of earth and planetary sciences at the University of California, Berkeley, and the study’s senior author. “The reason that they are problematic is that they are very hard to predict; it is not clear if there are any precursors that would allow you to provide warning.”

He and his team found that, while the ground around the geyser rose and seismicity increased somewhat before the geyser reactivated, and the area currently is radiating slightly more heat into the atmosphere, no other dormant geysers in the basin have restarted. The temperature of the groundwater propelling Steamboat’s eruptions has also not increased, and no sequence of Steamboat eruptions, other than the one that started in 2018, occurred after periods of high seismic activity.

“We don’t find any evidence that there is a big eruption coming. I think that is an important takeaway,” he said.

The study will be published this week in the journal Proceedings of the National Academy of Sciences.

Three simple questions

Manga, who has studied geysers around the world and created some in his own laboratory, set out with his colleagues to answer three main questions about Steamboat Geyser: Why did it reawaken? Why is its period so variable, ranging from three to 17 days? And, why does it spurt so high?

6 members of the Steamboat Geyser team arrayed around a table with their computers
Six members of the science team assembled around a table in McCone Hall at UC Berkeley in the summer of 2019, at work on the Steamboat Geyser project. Clockwise from lower left, Carolina Munoz-Saez, Anna Barth, Sahand Hajimirza, Tarsilo Girona, Sin-Mei Wu and Majid Rasht-Behesht. The three questions and hypotheses the team analyzed are on the greenboard, while the fluid dynamics equations that describe a geyser eruption are on the whiteboard. (UC Berkeley photo by Michael Manga)

The team found answers to two of those questions. By comparing the column heights of 11 different geysers in the United States, Russia, Iceland and Chile with the estimated depth of the reservoir of water from which their eruptions come, they found that the deeper the reservoir, the higher the eruption jet. Steamboat Geyser, with a reservoir about 25 meters (82 feet) below ground, has the highest column — up to 115 meters, or 377 feet — while two geysers that Manga measured in Chile were among the lowest — eruptions about 1 meter (3 feet) high from reservoirs 2 and 5 meters below ground.

“What you are really doing is you are filling a container, it reaches a critical point, you empty it and then you run out of fluid that can erupt until it refills again,” he said. “The deeper you go, the higher the pressure. The higher the pressure, the higher the boiling temperature. And the hotter the water is, the more energy it has and the higher the geyser.”

To explore the reasons for Steamboat Geyser’s variability, the team assembled records related to 109 eruptions going back to its reactivation in 2018. The records included weather and stream flow data, seismometer and ground deformation readings, and observations by geyser enthusiasts ( The researchers also looked at Steamboat’s previous active and dormant periods and those of nine other Yellowstone geysers, and at ground surface thermal emission data from the Norris Geyser Basin.

They concluded that variations in rainfall and snow melt were probably responsible for part of the variable period, and possibly for the variable period of other geysers as well. In the spring and early summer, with melting snow and rain, the underground water pressure pushes more water into the underground reservoir, providing more hot water to erupt more frequently. During winter, with less water, lower groundwater pressure refills the reservoir more slowly, leading to longer periods between eruptions. Because the water pushed into the reservoir comes from places even deeper than the reservoir, the water is decades or centuries old before it erupts back to the surface, he said.

In October, Manga’s team members demonstrated the extreme impact that water shortages and drought can have on geysers. They showed that Yellowstone’s iconic Old Faithful Geyser stopped erupting entirely for about 100 years in the 13th and 14th centuries, based on radiocarbon dating of mineralized lodgepole pine trees that grew around the geyser during its dormancy. Normally the water is too alkaline and the temperature too high for trees to grow near active geysers. The dormancy period coincided with a lengthy warm, dry spell across the Western U.S. called the Medieval Climate Anomaly, which may have caused the disappearance of several Native American civilizations in the West.

“Climate change is going to affect geysers in the future,” Manga said.

Geysers could help understand volcanic eruptions

Manga and his team were unable to determine why Steamboat Geyser started up again on March 15, 2018, after three years and 193 days of inactivity, though the geyser is known for being far more variable than Old Faithful, which usually goes off about every 90 minutes. They could find no definitive evidence that new magma rising below the geyser caused its reactivation.

In this 2015 video, volcanologist Michael Manga and student Esther Adelstein describe a laboratory experiment that helps to explain how geysers like Old Faithful work. (Video by Roxanne Makasdjian and Phil Ebiner, with geyser footage by Eric King and Kristen Fauria)

The reactivation may have to do with changes in the internal plumbing, he said. Geysers seem to require three ingredients: heat, water and rocks made of silica — silicon dioxide. Because the hot water in geysers continually dissolves and redeposits silica, every time Steamboat Geyser erupts, it brings up about 200 kilograms, or 440 pounds of dissolved silica. Some of this silica is deposited underground and may change the plumbing system underneath the geyser. Such changes could temporarily halt or reactivate eruptions if the pipe gets rerouted, he said.

Manga has experimented with geysers in his lab to understand why they erupt periodically. In these experiments, periodic eruptions appear to be caused by loops or side chambers in the pipe that trap bubbles of steam that slowly dribble out, heating the water column above until all the water boils from the top down, explosively erupting in a column of water and steam.

Studies of water eruptions from geysers could give insight into the eruptions of hot rock from volcanoes, he said.

“What we asked are very simple questions and it is a little bit embarrassing that we can’t answer them, because it means there are fundamental processes on Earth that we don’t quite understand,” Manga said. “One of the reasons (that) we argue we need to study geysers is that if we can’t understand and explain how a geyser erupts, our hope for doing the same thing for magma is much lower.”

The research, led by UC Berkeley graduate student and first author Mara Reed, resulted from a collaboration that started in one of the annual summer workshops put on by the Cooperative Institute for Dynamic Earth Research, or CIDER. Other co-authors are Carolina Munoz-Saez of the University of Chile and Columbia University in New York, Sahand Hajimirza of Rice University in Texas, Sin-Mei Wu of the University of Utah, Anna Barth of Columbia University, Társilo Girona of the University of Alaska, Majid Rasht-Behesht of Brown University in Rhode Island, Erin White of Yellowstone National Park in Wyoming, Marianne Karplus of the University of Texas at El Paso and Shaul Hurwitz of the U.S. Geological Survey in California. The work was supported by the National Science Foundation.


photo: Shaul Hurwitz/USGS

Climate change could affect famous Yellowstone geyser, Old Faithful, as paper co-authoured by EPS Chair Michael Manga shows severe drought ~800 years ago dried it up.

For more coverage:

Read article by Inside Science, Around 800 Years Ago, Yellowstone's Old Faithful Stopped Erupting

Read article by Science, Drought once shut down Old Faithful—and might again

Read article by Nature, Famed geyser Old Faithful went quiet in drought’s grip

Watch video by Weather Channel, Could Yellowstone’s Old Faithful Dry Up? Say It Isn’t So

Richard Allen and Qingkai Kong in front of the green Android character at Google headquarters. (Photo courtesy of Richard Allen)

A UC Berkeley idea to crowdsource every cellphone on the planet to create a global seismic network has been adapted by Google and incorporated into the Android operating system, kicking off an effort to build the world’s largest network of earthquake detectors.

Google announced today (Tuesday, Aug. 11) that Android cellphones — potentially billions of mobile phones around the planet — will automatically record shaking during an earthquake and feed the data into Google’s network. Google will analyze the data in real time and, for now, share online the magnitude, location and estimated area of shaking with anyone searching for “earthquake” or “earthquake near me.”

The technology company’s ultimate goal, like that of UC Berkeley, with its MyShake app, is to provide early warning of impending shaking from a quake to those in areas of the world without seismic or early warning networks, but with lots of personal cellphones that can serve as mini-seismometers.

“Google is building on what we have done with MyShake,” said Richard Allen, director of the Berkeley Seismological Laboratory and professor of earth and planetary science, who led the development of MyShake, which was released to the public last October.

MyShake provides Californians with early warning of ground shaking through the ShakeAlert system, which was rolled out last year by the governor’s Office of Emergency Services in conjunction with the U.S. Geological Survey, UC Berkeley and the California Institute of Technology. But the app also collects shaking data from cellphones and feeds it to UC Berkeley for analysis and research. Currently, MyShake has been downloaded by more than 1 million users around the world.

animation of characters dropping, covering and holding on

Earthquake early warning gives people time to drop, cover and hold on until the shaking stops, preventing injuries. (Animation courtesy of Google)

Google’s new Android OS will also provide Californians with early alerts through the ShakeAlert system, duplicating what MyShake does for iPhones, as well as Android phones.

Earthquake early warnings can come seconds to minutes before the ground begins to shake, giving MyShake users — and now Android users — time to duck, cover and hold on. The ShakeAlert system more broadly gives the state’s businesses, utilities, first responders and others time to secure equipment, pause activities or shut off equipment that could be damaged or incapacitated in a quake — or that could cause injuries.

Allen and UC Berkeley researcher Qingkai Kong consulted with Google over the past year to help the company develop and implement the Android Earthquake Alerts System.

“It’s a great project that allowed academic researchers to participate and help Google build the system,” Kong said. “It’s goal is to make an earthquake early warning system available globally that can benefit a lot of people and reduce a lot of casualties in the future. That is always the ultimate goal, to serve society and reduce earthquake hazards.”

Android’s built-in system works similarly to MyShake: Accelerometers in every phone detect shaking and send the data to Google, which uses massive processing to determine the pattern and estimate the spread of shaking.

In a blog post today, Marc Stogaitis, a principal software engineer with Android at Google, noted, “We’re essentially racing the speed of light (which is roughly the speed at which signals from a phone travel) against the speed of an earthquake. And lucky for us, the speed of light is much faster!”

UC Berkeley seismologists – this guy looks a lot like seismology lab director Richard Allen, complete with a Golden Bear cup – were among the earthquake experts consulted by Google before they incorporated ShakeAlert warnings into the Android operating system. (Video courtesy of Google)

According to Kong, Android will only source ground-shaking data from phones that are plugged in and charging and have not moved for a fixed period of time, in order to weed out shaking due to normal movement or to being carried in a pocket or bag.

Allen is hopeful that what Google learns from its crowdsourced earthquake detection network will be applicable to the MyShake experiment, even if outsiders cannot access the data because of privacy concerns.

“Google has great resources, but they are behind a wall,” he said. “I hope we can continue our partnership, so that we can continue to make advances, some inside Google, from which we can learn and apply these lessons outside Google to improve early warning and also better understand earthquake processes.”


Robert Sanders, UC Berkeley Media relations

In this video, doctoral student Basem Al-Shayeb (right) discusses a new gene-editing protein, CasΦ, which he and postdoc Patrick Pausch (left) discovered in a virus that attacks bacteria. Because it is very small and compact, the novel Cas protein should be easier to deliver to cells by a viral vector to alter plants or cure disease. (UC Berkeley video by Roxanne Makasdjian)

The DNA-cutting proteins central to CRISPR-Cas9 and related gene-editing tools originally came from bacteria, but a newfound variety of Cas proteins apparently evolved in viruses that infect bacteria.

The new Cas proteins were found in the largest known bacteria-infecting viruses, called bacteriophages, and are the most compact working Cas variants yet discovered — half the size of today’s workhorse, Cas9.

Smaller and more compact Cas proteins are easier to ferry into cells to do genome editing, since they can be packed into small delivery vehicles, including one of the most popular: a deactivated virus called adeno-associated virus (AAV). Hypercompact Cas proteins also leave space inside AAV for additional cargo.

As one of the smallest Cas proteins known to date, the newly discovered CasΦ (Cas-phi) has advantages over current genome-editing tools when they must be delivered into cells to manipulate crop genes or cure human disease.

“Adenoviruses are the perfect Trojan horse for delivering gene editors: You can easily program the viruses to reach almost any part in the body,” said Patrick Pausch, a postdoctoral fellow at the University of California, Berkeley, and in UC Berkeley’s Innovative Genomics Institute (IGI), a joint UC Berkeley/UCSF research group devoted to discovering and studying novel tools for gene editing in agriculture and human diseases. “But you can only pack a really small Cas9 into such a virus to deliver it. If you would have other CRISPR-Cas systems that are really compact, compared to Cas9, that gives you enough space for additional elements: different proteins fused to the Cas protein, DNA repair templates or other factors that regulate the Cas protein and control the gene editing outcome.”

Apparently these “megaphages” use the CasΦ protein  — the Greek letter Φ, or phi, is used as shorthand for bacteriophages — to trick bacteria into fighting off rival viruses, instead of itself.

“The thing that actually made me interested in studying this protein specifically is that all the known CRISPR-Cas systems were originally discovered in bacteria and Archaea to fend off viruses, but this was the only time where a completely new type of CRISPR-Cas system was first found, and so far only found, in viral genomes,” said Basem Al-Shayeb, a doctoral student in the IGI. “That made us think about what could be different about this protein, and with that came a lot of interesting properties that we then found in the lab.”

Among these properties: CasΦ evolved to be streamlined, combining several functions in one protein, so that it can dispense with half the protein segments of Cas9. It is as selective in targeting specific regions of DNA as the original Cas9 enzyme from bacteria, and just as efficient, and it works in bacteria, animal and plants cells, making it a promising, broadly applicable gene editor.

“This study shows that this virus-encoded CRISPR-Cas protein is actually very good at what it does, but it is a lot smaller, about half the size of Cas9,” said IGI executive director Jennifer Doudna, a UC Berkeley professor of molecular and cell biology and of chemistry and a Howard Hughes Medical Institute investigator. “That matters, because it might make it a lot easier to deliver it into cells than what we are finding with Cas9. When we think about how CRISPR will be applied in the future, that is really one of the most important bottlenecks to the field right now: delivery. We think this very tiny virus-encoded CRISPR-Cas system may be one way to break through that barrier.”

Pausch and Al-Shayeb are first authors of a paper describing CasΦ that will appear this week in the journal Science.

Biggiephages carry their own Cas proteins

The CasΦ protein was first discovered last year by Al-Shayeb in the laboratory of Jill Banfield, a a UC Berkeley professor of earth and planetary science and environment science, policy and management. The megaphages containing CasΦ were part of a group they dubbed Biggiephage and were found in a variety of environments, from vernal pools and water-saturated forest floors to cow manure lagoons.

graphic showing how a megaphage injects a Cas gene into a bacterium, turning on the bacteria's defenses against competing viruses

A megaphage (left), a member of a bacteriophage family Biggiephage, injects its DNA — including genes for CasΦ (red) — into bacterial cells to turn the bacteria against the phage’s competitor (top). The reddish Pac-Man-like figures are CasΦ proteins, enzymes that cut up viral DNA. The genome of the bacterium is shown in purple. (UC Berkeley image by Basem Al-Shayeb and Patrick Pausch)

“We use metagenomic sequencing to discover the Bacteria, Archaea and viruses in many different environments and then explore their gene inventories to understand how the organisms function independently and in combination within their communities,” Banfield said. “CRISPR-Cas systems on phage are a particularly interesting aspect of the interplay between viruses and their hosts.”

While metagenomics allowed the researchers to isolate the gene coding for CasΦ, its sequence told them only that it was a Cas protein in the Type V family, though evolutionarily distant from other Type V Cas proteins, such as Cas12a, CasX (Cas12e) and Cas14. They had no idea whether it was functional as an immune system against foreign DNA. The current study showed that, similar to Cas9, CasΦ targets and cleaves foreign genomes in bacterial cells, as well as double-stranded DNA in human embryonic kidney cells and cells of the plant Arabidopsis thaliana. It also can target a broader range of DNA sequences than can Cas9.

The ability of CasΦ to cut double-stranded DNA is a big plus. All other compact Cas proteins preferentially cut single-stranded DNA. So, while they may fit neatly into compact delivery systems like AAV, they are much less useful when editing DNA, which is double-stranded, inside cells.

As was the case after Cas9’s gene-editing prowess was first recognized in 2012, there is a lot of room for optimizing CasΦ for gene editing and discovering the best rules for designing guide RNAs to target specific genes, Pausch said.

Other co-authors of the paper are Ezra Bisom-Rapp, Connor Tsuchida, Brady Cress and Gavin Knott of UC Berkeley and Zheng Li and Steven E. Jacobsen of UCLA. The researchers were funded, in part, by the Paul G. Allen Frontiers Group, National Institutes of Health Somatic Cell Genome Editing consortium (U01AI142817-02) and National Science Foundation (DGE 1752814).