Geologist Thomas Dibblee Jr. and the Theory Behind Pinnacles National Park’s 200-Mile Tectonic Journey

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Pinnacles National Park’s open landscape of dramatic rock formations and craggy spires looks otherworldly, especially in golden hour light. But few people who visit the park, located in Central California, southeast of the San Francisco Bay Area, are aware that the rock formations were once at the center of a fierce debate in the history of California geology.

And at the center of the controversy was a young geologist named Thomas Dibblee Jr.

Pinnacles National Park, formerly Pinnacles National Monument, tells the story of ancient volcanic activity and the relentless geologic forces of the San Andreas Fault. This fault, a major boundary between the Pacific and North American tectonic plates, is the platform for the dramatic northward journey of the park’s volcanic remnants. Dibblee’s research illuminated how, over millions of years, the landscapes we see today were sculpted by the movements of these tectonic plates and how the shape of California as a state has changed dramatically as a result.

The crux of Dibblee’s discovery lies in the relationship between Pinnacles National Park and a volcanic source located near present-day Neenach, close to Palmdale in Southern California. The geological narrative that Dibblee pieced together revealed that the rock formations at Pinnacles originated from volcanic eruptions that occurred approximately 23 million years ago, near what is now Neenach. Over millions of years, the relentless movement along the San Andreas Fault has transported these formations over 195 miles (314 kilometers) to their current location. At the time, very few people, geologists included, believed that was possible.

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Dibblee had to be wrong. But it turned out, he was not, and his measurements and discovery launched a passionate debate about the speed of geologic forces.

Dibblee’s findings not only shed light on the significant distances that landscapes can travel over geological timeframes but also provided a tangible connection between the theory of plate tectonics and observable geological features. The juxtaposition of Pinnacles National Park and the Neenach volcanic formation serves as a clear indicator of the San Andreas Fault’s role in shaping California’s geological, indeed it’s physical, identity.

A key aspect of Dibblee’s methodology was his keen observational skills, which enabled him to recognize that the rocks at Pinnacles National Park were strikingly similar in composition and age to those near Neenach, even though these areas are separated by about 195 miles (314 kilometers) today. He noted the volcanic origins of these formations and, through detailed mapping, was able to correlate specific rock types and strata between these distant locations.

Another crucial element in Dibblee’s discovery was his understanding of the San Andreas Fault as a major geological feature capable of significant lateral movement (remember the San Andreas is a slip or sliding fault). By correlating the age and type of rocks across this fault line, Dibblee inferred that the only plausible explanation for the similarity between the rocks at Pinnacles and those near Neenach was that they had once been part of the same volcanic field, which had been split and displaced over millions of years due to the movement of the San Andreas Fault.

Rock formations at Pinnacles National Park (Brocken Inaglory)

Dibblee’s work also benefited from the broader scientific context of his time, particularly the emerging theory of plate tectonics in the mid-20th century. This theoretical framework provided a mechanism for understanding how large-scale movements of the Earth’s crust could result in the displacement of geological formations over vast distances. Dibblee’s findings at Pinnacles and Neenach became a compelling piece of evidence supporting the theory of plate tectonics, showcasing the San Andreas Fault’s role in shaping California’s landscape.

But Dibblee’s ideas were controversial at the time. Many in the scientific community were hesitant to embrace a theory that suggested such dramatic movement across the Earth’s crust, partly because it challenged existing paradigms and partly due to the limitations of the geological evidence available at the time. The prevailing theories favored more static models of the earth’s crust, with changes occurring slowly over immense periods. Dibblee’s insights into tectonic movements and the geological history of regions like the Pinnacles National Park were ahead of their time and laid the groundwork for the acceptance of plate tectonics.

This Pinnacles revelation was groundbreaking, emphasizing the dynamic and ever-changing nature of the Earth’s surface. Dibblee’s ability to piece together these monumental shifts in the Earth’s crust from his detailed maps and observations has left a lasting impact on our understanding of geological processes. His work at Pinnacles and the recognition of its journey alongside the San Andreas Fault underscores the importance of detailed geological mapping in unraveling the Earth’s complex history.

San Andreas Fault looking northwest onto the Carrizo Plain (John Wiley)

Born in 1911 in Santa Barbara, California, Dibblee’s life and work were deeply intertwined with the rugged terrains and picturesque landscapes of the Golden State, Dibblee’s journey into geology began at a young age, fostered by his natural curiosity and the geological richness of his native state.

After earning his degree from Stanford in 1936, Dibblee embarked on his professional journey with Union Oil, later moving to Richfield. It was during this period that his extensive field mapping efforts culminated in the discovery of the Russell Ranch oil field near New Cuyama. By 1952, Dibblee had meticulously mapped every sedimentary basin in California with potential for oil, cementing his legendary status as a petroleum geologist. His reputation for traversing the state’s backcountry on foot for extended weeks became a defining aspect of his character and contributed to his storied career in geology.

Dibblee moved on to a career at the United States Geological Survey (USGS) that would span over six decades, much of it spent with the agency and then later through independent projects. His work ethic and passion for fieldwork were unparalleled; Dibblee was known for his meticulous and comprehensive approach, often spending long days in the field, mapping out California’s complex strata with precision and care.

Over his career, Dibblee mapped over 240,000 square kilometers of California’s terrain, an achievement that provided an invaluable resource for understanding the state’s geological history and structure. He mapped large swaths of the Mojave Desert, the Coast Range and the Los Padres National Forest, earning a presidential volunteer action award in 1983 from President Reagan.

His maps are celebrated for their accuracy and detail, serving as critical tools for academic research, oil exploration, environmental planning, and education. The Dibblee Geological Foundation, established to honor his work, continues to publish these maps, ensuring that his legacy lives on.

Dibblee’s insights into the geology of California were pivotal in several areas, including the understanding of the San Andreas Fault, a major fault line that has been the focus of extensive seismic research due to its potential for large earthquakes. Dibblee’s mapping efforts helped to clarify the fault’s characteristics and behavior, contributing to our understanding of earthquake risks in California and aiding in the development of safer building practices and disaster preparedness strategies.

Furthermore, Dibblee’s work shed light on the process of plate tectonics and the geological history of the western United States. His observations and mapping of sedimentary formations and fault systems in California provided empirical evidence that supported the theory of plate tectonics, a cornerstone of modern geology that explains the movement of the Earth’s lithospheric plates and the formation of various geological features.

Thomas Dibblee Jr.’s contributions to the field of geology are not just confined to his maps and scientific discoveries. He was also a mentor and inspiration to many aspiring geologists, sharing his knowledge and passion for the Earth’s history through lectures, field trips, and personal guidance. His dedication to his work and his ability to convey complex geological concepts in an accessible manner made him a respected figure among his peers and students alike. Through his dedication and pioneering work, Dibblee has left an indelible mark on the field of geology, making him a true giant in the scientific exploration of California as well as our planet.

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Feathers on the Flyway: Unraveling Avian Mysteries at Bear Divide with the Moore Lab

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“Personally, I really think it’s one of the best birding spots in the world,” Ryan Terrill, science director at the Klamath Bird Observatory.

Within a 45 minute drive from the urban chaos of downtown Los Angeles, lies a natural, ornithological marvel: Bear Divide, a vital corridor for the annual migration of numerous bird species. Every year — roughly between March 15 and June 15, with peak migration between April 10 and May 20 — thousands of birds funnel through the narrow pass. The divide is a small dip in the otherwise impregnable San Gabriel mountains, allowing birds in the midst of their migration to pass through safely at relatively low altitudes. This area is not just a haven for bird enthusiasts but also a critical research site, especially for the team from the Moore Lab of Zoology at Occidental College, who have been delving into the intricacies of these migratory patterns.

The Moore Lab of Zoology is renowned for its extensive bird specimen collection, one of the largest of its kind in the world for Mexican birds.

Part of the large bird collection at the Moore Lab at Occidental College in Pasadena (Erik Olsen)

Bear Divide is strategically positioned along the Pacific Flyway, a significant north-south migratory route used by birds traveling between Alaska and Patagonia. The geographical features of the San Gabriels provide an ideal resting and feeding ground for these birds, making Bear Divide a crucial stopover during their long journeys. It’s this unique combination of location and topography that makes Bear Divide an essential component of avian migration.

The discovery of Bear Divide was a lucky happenstance. A bird researcher was conducting overnight monitoring in the spring of 2016, and when morning came, he noticed legions of small songbirds whizzing past his monitoring spot. His report caught the attention of postdoc bird scientist Ryan Terrill at Moore Lab at the time, and he began an effort to monitor the birds. Terrill and his team would ultimately record as many as 20,000 birds in a single morning.

“It really is overwhelming to stand on the road and have 5,000 birds of 80 species fly by your knees in a morning,” Terrill said. The effort has continued to this day with startling results. Terrill has since left and is now the science director at the Klamath Bird Observatory.

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“Last year 2023 we counted 53,511 birds of 140 species from February to May,” said John McCormack, a professor of biology and the Director and Curator of the Moore Laboratory of Zoology. “And of course, we missed many thousands more because most travel at night. It’s easy to say that there are hundreds of thousands of birds passing through Bear Divide.”

As many as 13,000 western tanagers, lazuli buntings, chipping sparrows, hermit warblers, orioles, grosbeaks and warblers pass through Bear Divide on a single day. Why they do so, is not entirely understood. The unusual topography of Bear Divide essentially serves as a funnel for the migrating birds, with many of them shooting through the gap just a meter or two above ground.

“Personally, I really think it’s one of the best birding spots in the world,” Terrill told the LA Times.

McCormack says that the “ultimate goal is to better understand the Pacific Flyway and how it’s used, especially by small terrestrial birds. Little is known about their movements because they are hard to see and usually travel at night.”

Because many of the species sighted at Bear Divide are in steep decline. The lab says that year-to-year counts will help set a baseline for future trends that can be associated with weather, climate, and urbanization. “Tracking individual birds will give granular knowledge on how migratory birds use the landscape, which helps individuals and homeowners create corridors for them to travel,” says McCormack.

The best time to catch the show at Bear Divide is late winter early Spring. McCormack says Cliff Swallows and Lawrence’s Goldfinch are some of the early movers in March, and that by May, streaking by are Yellow Warblers, sunset-faced Western Tanagers, and bright blue Lazuli Buntings.

“There is so much we still don’t know about these birds and their world,” Lauren Hill, the site’s lead bird bander, told the Los Angeles Times. “For example, no one knows where they were before showing up here after sunrise.”

Lazuli Bunting zips past the camera at Bear Divide (Ryan Terrill)

The team is counting birds in order to establish a baseline of the populations coming through Bear Divide so they can understand how much we are changing the environment and what effect that may have on bird populations, many of which are in severe decline.

Their research spans a variety of topics, including how climate change is impacting migration routes and the effects of urbanization on bird populations. The lab has recently begun a program to put satellite trackers on birds at Bear Divide to follow individual birds, providing deep insight into their migration and resting patterns. This research is not only pivotal in understanding avian behavior but also crucial in shaping conservation policies.

One of the most fascinating aspects of Bear Divide is the sheer variety of bird species it attracts. From the diminutive hummingbirds to the impressive birds of prey, each species adds a unique dimension to the study of migration. The Moore lab’s findings have shed light on the varied responses of different species to environmental changes, offering a glimpse into the broader ecological shifts occurring across the globe.

One compelling result of the Moore Lab’s study at Bear Divide suggests that the peak of a particular species’ migration is correlated with the latitude of its breeding site. Species that breed at higher latitudes migrated through Bear Divide at later dates. It’s also unusual in the West for species to migrate during the day. Most species of birds using the Pacific Flyway are known to migrate at night.

In addition to its scientific contributions, the Moore lab is also known for its involvement in citizen science. Collaborating with local birdwatchers and volunteers, the lab extends its research capabilities and cultivates a community actively engaged in bird conservation. This collaborative approach not only enhances the breadth of their research but also underscores the importance of community involvement in conservation efforts.

Bear Divide is on public land, so anyone with a legitimate research project can get permission to work there. UCLA graduate student Kelsey Reckling, who has worked as a counter at Bear Divide since the beginning, is leading the counting efforts this Spring to understand changes in numbers of birds and species across years. Cal State L.A. graduate student Lauren Hill lea ds the group of bird banders, who catch some of the birds and record data, attaching a lightweight metal band around one leg and releasing them. Her lab mate Tania Romero is putting small, lightweight tracking devices on Yellow Warblers, which send signals to a network of tracking (MOTUS) towers across the continent.

Many bird species are under serious threat around the globe from a number of different impacts, including climate change, pesticides and habitat loss. Birds play a critical role in the health of our planet. They regulate ecosystems by preying on insects, pollinating plants, and spreading seeds. Healthy ecosystems are important for breathable air, food, and a regulated climate.

According to a 2019 study, nearly 3 billion breeding birds have been lost in North America and the European Union since 1970. That’s about 30% of the bird population in North America. The 2022 State of the Birds Report for the United States found that bird declines are continuing in almost every habitat, except wetlands. Protecting birds’ habitats, and migration routes and reducing mortality through conservation efforts are crucial to ensuring the survival of these magnificent creatures.

The research conducted at Bear Divide by the Moore lab transcends academic interests, emphasizing the interconnectivity of ecosystems and underscoring the need to preserve natural migration corridors amid urban expansion. The insights gained here are invaluable to both the scientific community and conservation efforts, highlighting the need for a balanced approach to wildlife preservation and ecological sustainability.

“What’s magical about Bear Divide is that it’s the first real place to see small, migrating birds at eye level in daylight hours,” says McCormack. “I don’t want to oversell it: it’s still a lot of small birds zinging by in a wide open place and it takes a while to get good at identifying them. But by seeing them out there, struggling against the wind and the cold, but still making progress, it gives you a real sense of how amazing their journeys are–and how we shouldn’t make them harder if there’s anything we can do about it.”

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The Blythe Intaglios are the California’s Nazca Lines. They are True Mysteries Etched in Earth.

Blythe Intaglio of a human figure in Southern California (Wikipedia)

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In the vast expanses of California’s Colorado Desert, less than four hours from Los Angeles, a series of ancient and enigmatic figures etched into the earth—the Blythe Intaglios—have long puzzled anthropologists and captivated the imagination of those who visit them or view them from the sky. They were brought to modern attention somewhat by chance. In 1932, George Palmer, a pilot flying over the Mojave Desert between Las Vegas, Nevada and Blythe, glimpsed these enigmatic formations, sparking curiosity and awe.

Named for the nearby town of Blythe, California, these large geoglyphs (human-made designs created on the ground by arranging or moving objects in a landscape), sprawl across the desert floor, and are an extraordinary example of prehistoric art, yet they remain one of the lesser-known archaeological wonders of North America. The Colorado Desert, just south of the Mojave, contains the only known desert intaglios in North America.

The Blythe Intaglios are best observed from above by drone or by plane, where their full scale and intricacy become apparent. The largest figure – of a human with outstretched arms – spans an immense 171 feet, an impressive endeavor considering the primitive tools likely used in their creation. One has to wonder why they were created at all since the people who made them certainly had no way of viewing them from the air. In addition to humans, the figures depict animals such as a rattlesnake and possibly a horse (yeah, what is that thing?), as well as geometric shapes, each meticulously carved by removing the dark desert varnish to reveal the lighter soil underneath. Intaglios in general are classified by their shapes, such as anthropomorphs (humanlike), zoomorphs (animal-like) and various geometric shapes.

The intaglios are mostly located along the Colorado River, a fact that some scientists consider significant. Rivers often hold a central place in the spiritual and cultural lives of indigenous peoples. For the tribes associated with the Blythe Intaglios, such as the Mojave and Quechan, the Colorado River was likely a vital part of their spiritual and everyday life. The proximity of these geoglyphs to the river suggests that they could have been part of a broader cultural landscape that included the river as a critical element. The river may have been seen as a source of life and a spiritual boundary, making the nearby land a significant place for creating these monumental figures.

While the Nazca Lines in Peru have gained worldwide fame, the Blythe Intaglios, though similar in form and function, have remained relatively obscure. Most Californians probably have no idea that such unique archaeological artifacts can be found in the state, let alone so close to a major urban center. This obscurity, however, adds to their mystique.

The geoglyphs are believed to date back at least a thousand years, but their exact age remains uncertain. If the quadruped figures represent horses (reintroduced in North America by the Spanish) then a historical date of sometime after the 1500s would be supported. Archaeologist Jay von Werlhof obtained radiocarbon dates for the figures, ranging from 900 BCE to 1200 CE. The human figures, particularly the largest, are thought to represent Mastamho, the creator of life in Mojave and Quechan mythology. The animal figures, like the mountain lions, are steeped in symbolic meaning, potentially reflecting the tribes’ cosmology and spiritual beliefs.

Nazca Lines in Peru. (UNESCO World Heritage Site)

The precise purpose of the Blythe Intaglios is a matter of ongoing debate. Some scholars propose that they were part of religious rituals or celestial observances. The alignment and positioning of the figures suggest a possible astronomical function, marking significant events in the lunar or solar calendars. Or perhaps making them was just a fun way to pass the time and express creativity.

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Despite their historical and cultural significance, the Blythe Intaglios have not been immune to threats. Off-road vehicle traffic and natural erosion have damaged some of the figures. Conservation efforts are in place, but the remote location and sheer scale of the site present unique challenges. Fences have been erected around some figures to protect them, but much work remains to ensure their preservation.

California’s Colorado Desert (Wikipedia)

The Blythe Intaglios are more than just ancient art; they are a wonderful example of the rich and diverse cultural heritage of the indigenous peoples of the Southwest. These geoglyphs offer a window into a past that likely predates European influence, a past that is integral to understanding the complex tapestry of American history. Places like the Blythe Intaglios are in constant threat of disappearing forever, but they’re important because they connect us with the human past and remind us of the power of human expression over time and the mysteries beneath our feet.

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The Enigmatic Island Fox: A Tale of Survival and Conservation

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In the rugged, isolated beauty of California’s Channel Islands, a small, curious creature scampers through the chapparal, playing a crucial role in the archipelago’s ecosystem. It’s the Island Fox (Urocyon littoralis), a species that encapsulates both the vulnerability and resilience of island ecosystems.

The island fox only lives on six of the eight Channel Islands off the coast of southern California–they are found nowhere else on Earth. Each island population is recognized as a separate endemic or unique subspecies. This divergence is a classic case of allopatric speciation, where geographic isolation leads to the evolution of different species.

The Island Fox, notably smaller than its mainland cousin, the gray fox, stands as a striking example of insular dwarfism – a phenomenon found in the theory of island biogeography where species evolve smaller sizes on islands. It should be noted that island biogeography, which explores the distribution of species and ecosystems in island environments, finds a perfect case study in the Channel Islands. For instance, the discovery of remains of the pygmy mammoth (Mammuthus exilis) on Santa Rosa Island provides a classic example of how isolation and limited resources can lead to significant evolutionary changes.

Skeleton of the Pygmy Mammoth at the Santa Barbara Museum of Natural History

The Island Fox is known for its curiosity and intelligence. It’s primarily nocturnal but is often active during the day, especially when tourists and their food are around. Visitors to the most popular Channel Islands like Anacapa, Santa Rosa, and Santa Cruz may regularly see the foxes scurrying around campsites looking for scraps of food. They readily approach humans, perhaps an unfortunate sign that they have become too habituated to humans. The island fox is an omnivore, with a diet ranging from fruits and insects to small mammals and birds. Its diet shifts with the seasons, reflecting the availability of different food sources on the islands.

Island Foxes typically form monogamous pairs during the breeding season, which runs from January to March. The female gives birth to a litter of two to four pups around 50 days after mating. These pups are weaned and ready to fend for themselves after about 9 months, reaching sexual maturity at 10 months. The average lifespan of an Island Fox in the wild is 4 to 6 years, though they can live longer in captivity.

Island Fox on the Channel Islands (Photo: Erik Olsen)

The story of the Island Fox’s conservation is one of remarkable success but also a stark reminder of the fragility of island ecosystems. In the late 1990s, the Island Fox population faced a catastrophic decline, primarily due to predation by golden eagles and a disease outbreak. By 2004, fewer than 100 foxes remained on some islands, leading to their classification as an endangered species.

Island Fox looking for food scraps. (Photo: Erik Olsen)

A concerted effort by conservationists, including the National Park Service and the Nature Conservancy, initiated a recovery program. This program involved breeding foxes in captivity, vaccinating them against diseases, and relocating golden eagles while reintroducing bald eagles, a natural competitor. Remarkably, by 2016, the Island Fox populations had bounced back sufficiently for them to be removed from the endangered species list, marking one of the fastest recoveries of an endangered species in U.S. history.

The Island Fox’s journey from the brink of extinction to a conservation success story is a testament to the power of dedicated conservation efforts. It also highlights the importance of maintaining ecological balance in sensitive environments like the Channel Islands.

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California’s SLAC and the Mission to Unveil the Mysteries of Matter and the Cosmos

The BaBar Detector at SLAC with physicist Michael Kelsey inside wearing a red hard hat, 2002.
*(Peter Ginter/SLAC National Accelerator Laboratory)*

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The SLAC National Accelerator Laboratory in Menlo Park, California, is a testament to human curiosity and the pursuit of the unknown. Since its inception in 1962, originally as the Stanford Linear Accelerator Center (as it was previously known), it has been on the forefront of scientific discovery in numerous scientific disciplines. It is truly one of the nation’s great scientific institutions, being at the forefront of numerous major discoveries that have deeply impacted – and will impact – the world.

Six scientists have received four Nobel prizes for their groundbreaking research conducted at SLAC, which led to the discovery of two elementary particles, confirmed that protons consist of quarks, and elucidated the process by which DNA orchestrates the synthesis of proteins in cells.

Stanford’s Roger Kornberg received the 2006 chemistry Nobel for work on RNA transcriptase, shown on screens.
*(Peter Ginter/SLAC National Accelerator Laboratory)*

Administered by Stanford University and sponsored by the U.S. Department of Energy, SLAC has grown into a multifaceted research institution that explores a broad program in atomic and solid-state physics, chemistry, biology, and medicine. The lab employs the use of X-rays generated from synchrotron radiation and a free-electron laser, among other tools, to push the boundaries of our understanding in areas ranging from elementary particle physics to cosmology.

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SLAC’s roots can be traced back to the construction of the 3.2-kilometer Stanford Linear Accelerator in 1966, the world’s longest linear accelerator at the time. This remarkable structure has been pivotal in fundamental research that led to the discovery of the charm quark in 1976, the quark structure inside protons and neutrons in 1990, and the tau lepton in 1995, each discovery earning a Nobel Prize in Physics. This pioneering spirit is also embedded in SLAC’s cultural heritage, having provided a meeting space for the Homebrew Computer Club, which significantly contributed to the home computer revolution of the late 1970s and early 1980s. For example, Steve Wozniak debuted the prototype Apple-1 at the Homebrew Computer Club in 1976.

SLAC has also played a significant role in the digital age, hosting the first World Wide Web server outside of Europe in December 1991, a milestone that underscores its contribution beyond the realm of physics. In the 1990s, the Stanford Linear Collider delved into the properties of the Z boson, further cementing SLAC’s position at the cutting edge of particle physics research.

New projects and experiments are undertaken at SLAC all the time, and new discoveries are constantly being made to help us understand the nature of matter, biological processes and the evolution of the universe, as well as to help bring us into a greener future. In November 2023, a team at SLAC along with the Toyota Motor Company made significant advances in fuel cell efficiency.

The Linac Coherent Light Source (LCLS), a free-electron laser facility, has been a highlight of SLAC’s facilities, providing intense X-ray radiation for diverse research areas since 2009. In September 2023, SLAC fired up the world’s most powerful X-ray laser, the LCLS-II, to explore atomic-scale, ultrafast phenomena that are key to a broad range of applications, from quantum materials to clean energy technologies and medicine.

“This achievement marks the culmination of over a decade of work,” said LCLS-II Project Director Greg Hays. “It shows that all the different elements of LCLS-II are working in harmony to produce X-ray laser light in an entirely new mode of operation.”

It was in the facility that scientists and researchers developed the first X-ray free-electron lasers (XFELs). XFELs are like X-ray microscopes, and generate exceptionally bright and fleeting bursts of X-ray light, enabling researchers to observe the dynamics of molecules, atoms, and electrons with unparalleled clarity, exactly as these events unfold in their native, rapid timescales—a realm where the intricacies of chemistry, biology, and materials science play out. These facilities have played a pivotal role in numerous scientific breakthroughs, such as producing the first “molecular movie” that reveals the intricacies of complex chemical reactions, capturing the precise moments when plants and algae harness solar energy to generate the oxygen we rely on, and probing the intense conditions that shape the formation of planets and extraordinary events like diamond precipitation.

Over the years, SLAC has evolved to support a growing community of scientists. As of 2021, the lab employs approximately 1,600 staff members from 55 different countries, in addition to 470 postdoctoral researchers and graduate students. The center welcomes over 3,000 visiting researchers annually. This community has access to facilities such as the Stanford Synchrotron Radiation Lightsource for materials science and biology experiments and the Fermi Gamma-ray Space Telescope for astrophysics research.

After decades of effort and help from SLAC’s X-ray laser, scientists have finally seen the process by which nature creates the oxygen we breathe. (SLAC)

The lab is also working at the forefront of astronomy and imaging. The SLAC National Accelerator Laboratory is at the helm of an ambitious project, crafting the world’s largest digital camera for the Vera Rubin Observatory’s Legacy Survey of Space and Time (LSST). Set to capture the southern sky from high on a mountaintop in Chile, this camera is a marvel of engineering and scientific collaboration. Its 3.2-gigapixel capacity allows it to snap detailed images every 15 seconds, offering an unprecedented window into the cosmos. The camera’s wide field of view can image an area 40 times larger than the full moon in one shot, and its advanced filters enable astronomers to probe the universe across a range of wavelengths. As part of the decade-long LSST, it will gather vast amounts of data, propelling our understanding of dark matter, dark energy, galaxy formation, and more

SLAC has developed the world’s largest digital camera for the Vera Rubin Observatory’s Legacy Survey of Space and Time (LSST)

In 2008, the lab was renamed from the Stanford Linear Accelerator Center to SLAC National Accelerator Laboratory, reflecting a broader scientific mission. Since then, the lab has continued to receive significant funding, including $68.3 million in Recovery Act Funding in 2009. Notably, SLAC and Stanford University initiated the Bits and Watts project to develop better, greener electric grids, although SLAC later withdrew due to concerns over an industry partner.

SLAC’s current endeavors include the Facility for Advanced Accelerator Experimental Tests (FACET), where research on plasma acceleration continues to advance the field. Theoretical research at the lab spans quantum field theory, collider physics, astroparticle physics, and particle phenomenology. Moreover, SLAC has contributed to the development of the klystron, a high-power microwave amplification tube that amplifies high radio frequencies and has aided in archaeological discoveries such as revealing hidden text in the Archimedes Palimpsest.

Other recent updates from SLAC include a new system for turning seawater into hydrogen fuel. They have also made advancements in understanding the production of nitroxide, a molecule with potential biomedical applications, and the operation of superconducting X-ray lasers at temperatures colder than outer space.

The SLAC National Accelerator Laboratory’s legacy is rich with scientific triumphs, and its future beckons with the promise of unraveling more of the universe’s deepest secrets. Whether through peering into the atomic structure or probing the vast cosmos, SLAC remains a beacon of discovery and innovation.

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Roadcut Revelations: Unearthing California’s Deep History Along the Highway

Roadcut in Southern California on Angeles Crest Highway (Photo: Erik Olsen)

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“Man is a geologic agent,” the late California geologist Eldridge Moores.

Roadcuts in California, those slices through hills and mountainsides made during the construction of roads, are like open books to geologists. They reveal the intricate and often dramatic geological history of the state. When you drive along the highways of California, you’re likely to pass by these exposed cliffs of rock. To the everyday traveler, they might just be a part of the landscape, but to geologists, they are invaluable windows into the Earth’s past.

““Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave,” wrote the great geology (and many other topics) writer John McPhee in his excellent book Annals of the Former World. “To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrane.”

Glacier carved domes tell the story of thousands of years of glaciation in California. (Photo: Erik Olsen)

Roadcuts expose layers of rock that have been hidden from view for millions of years. Each layer, or stratum, tells a story of what the environment was like when that layer was deposited. By studying these layers, geologists can reconstruct a timeline of events that shaped the region. For example, they can identify periods of volcanic activity, times when the area was submerged under an ancient ocean, or epochs when massive glaciers were carving out the valleys.

California is especially interesting due to its active tectonic setting. It’s not just the San Andreas Fault that captivates geologists; there are numerous lesser-known faults that crisscross the state, and roadcuts can expose these hidden fractures. By studying the composition of rocks along these faults, geologists learn about the nature of past seismic activity and can make predictions about future earthquakes.

The rock composition in California varies widely, offering a rich tapestry of geological history. In the Sierra Nevada, granite roadcuts tell of a time when massive chambers of magma slowly cooled and crystallized deep beneath the Earth’s surface. Elsewhere, roadcuts through sedimentary rocks like sandstone and shale may contain fossils, giving clues about the life forms that once inhabited the region.

The San Gabriel Mountains consist of granite rocks of several kinds and a variety of other crystalline rocks, mainly schists, some of which were originally shales and sandstones but have been altered (metamorphosed) by great igneous intrusions and compression. (Photo: Erik Olsen)

These man-made artifacts also reveal the forces that have shaped California’s diverse landscapes. In roadcuts, geologists might find evidence of powerful geological processes such as metamorphism, where existing rock types are transformed into new types due to high pressure and temperature conditions. For instance, the presence of metamorphic rocks like schist and gneiss can indicate ancient collision zones where Earth’s tectonic plates have crashed together.

The value of California roadcuts is wonderfully illustrated in John McPhee’s “Assembling California.” The book is an excellent narrative that weaves the tale of California’s complex geology with the lives of the geologists who study it. Eldridge Moores, a late prominent geologist from the University of California, Davis (Moores died in 2018), played a significant role in deciphering the geological history of the region, particularly through his fieldwork involving roadcuts.

Roadcut in San Gabriel mountains. (Photo: Erik Olsen)

At the time Eldridge Moores entered the field, the theory of plate tectonics was only beginning to gain traction. In the early 1960s, the idea that continents drifted and that vast slabs of the Earth’s crust moved over the mantle was still controversial, met with skepticism by many geologists trained in older, fixist models. Moores, however, embraced the theory early, recognizing in it an explanation for the chaotic structures he saw in California’s mountain belts. As a young researcher, he studied the Troodos ophiolite in Cyprus, an exposed section of ancient oceanic crust, and realized that similar rock assemblages—serpentinized peridotites, deep-sea sediments, and basaltic lavas—were scattered across California.

“It was a very exciting time. I still get goosebumps even talking about it,” Moores told KQED in 2017. “A turning point, I think it was, in the plate tectonic revolution, that was the watershed of geology.”

With plate tectonics as a guiding framework, Moores understood that these rocks were remnants of vanished oceans, relics of seafloor that had been uplifted and accreted onto the edge of North America. His work helped reveal that much of California had arrived in pieces, a geological patchwork of island arcs, deep-sea basins, and continental fragments welded together by subduction. While others were still debating the validity of plate tectonics, Moores was already applying it, using it to decode the assembly of an entire state.

*Eldridge Moores at the Cordelia fault.* (Photo: UC Davis)

Moores was renowned for his work on ophiolites, sections of the ocean floor that have been thrust up onto the continent. One of his notable discoveries was the identification of ophiolite sequences in the roadcuts along the highways of the Sierra Nevada. These discoveries were crucial in understanding the ancient tectonic movements that shaped western North America.

Through roadcuts, Moores and his colleagues were able to observe and study the juxtaposition of different rock types, providing further evidence for the theory of plate tectonics. They could literally walk along the cuts and see how different terranes—large packets of rock with a distinct geological history—were stitched together like a geological quilt, offering insight into the past locations of tectonic plates.

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“Nature is messy,” Moores once told McPhee. “Don’t expect it to be uniform and consistent.”

There are thousands of roadcuts across California, each exposing a fragment of the state’s chaotic geology. The Palmdale Roadcut, a striking geological feature along the San Andreas Fault, has been an invaluable resource for geologists studying the dynamics of this infamous fault line. This natural cut exposes a cross-section of the earth, revealing layers of rock and sediment that have been shifted and shaped by seismic activity over millions of years. The rock here is a chaotic mélange—fault gouge, shattered granite, and twisted layers of sedimentary rock that have been pulverized and ground together by the relentless motion of the Pacific and North American plates. By analyzing these layers, geologists can better understand the history and behavior of the San Andreas Fault, including the patterns of past earthquakes and the movements of tectonic plates. This, in turn, contributes significantly to the broader understanding of seismic risks and aids in preparing for future seismic events.

The Palmdale Road Cut on Hwy 14 in Southern California is a 90-foot slice through swirling sediments that have spent millions of years being squeezed and twisted by the San Andreas fault. Some say that this view of the fault is one of the best in all of California.
(Photo: Erik Olsen)

Another geologist, Garniss Curtis, used California roadcuts to study volcanic rocks and their embedded minerals, which allowed for the dating of geologic events with greater precision. His work on the potassium-argon dating method turned roadcuts into time machines, where the age of rocks could be determined with the help of exposed minerals.

One of California’s most well-known roadcuts, the Charlie Brown Outcrop (map), is a favorite among geologists. Located along Highway 178 near the Nevada border, it has been highlighted by geology teacher Garry Hayes, author of the acclaimed Geotripper blog. Hayes says of the roadcut (also known as the Shoshone Roadcut):

“There are really three stories told in this exposure, that of distant ash eruptions, a violent eruption close by, and earthquakes with associated mountain-building.”

Charlie Brown outcrop along highway 178 in California. (Google Maps)

These geologists, among others, have used roadcuts as a means to peel back the layers of time, revealing the processes that have operated to create the state’s diverse geologic scenery. Roadcuts have provided the evidence for groundbreaking theories and have been instrumental in mapping the geological evolution of California. The work of these scientists exemplifies the roadcut’s role as a natural laboratory, a place where Earth’s geologic history is on full display for those who know how to read the rocks.

Moreover, roadcuts are crucial for educating the next generation of geologists. They serve as natural laboratories where students can practice identifying rock types, deciphering the sequence of geological events, and understanding the dynamic forces that continue to shape the Earth.

Roadcuts in California, those slices through hills and mountainsides made during the construction of roads, are like open books to geologists. They reveal the intricate and often dramatic geological history of the state. (Photo: Erik Olsen)

In Assembling California, McPhee remarked that “geologists are like dermatologists: they study, for the most part, the outermost two per cent of the earth. They crawl around like fleas on the world’s tough hide, exploring every wrinkle and crease, and try to figure out what makes the animal move.”

Manmade creations like roadcuts greatly assist geologists in their work. In essence, roadcuts are not just incidental byproducts of infrastructure development; they are key to understanding California’s complex geological evolution. They tell stories of ancient environments, tectonic upheavals, and the slow but inexorable forces that continue to mold the landscape. For geologists in California, the roadcut is a portal into the deep past, offering a tangible connection to the processes that have made the state what it is today.

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The Mystical Sentinels of the Mojave: Unraveling the Secrets of the Joshua Tree

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Standing tall against the backdrop of the sun-scorched Mojave Desert, the Joshua Tree (Yucca brevifolia) is an emblematic figure of resilience and beauty. With its twisted, bristled limbs reaching towards the sky, this iconic species is not just a tree but a symbol of the untamed wilderness that is California’s desert landscape.

The Joshua Tree’s biology is as unique as its silhouette. It’s often considered to be a member of the Agavaceae family (along with agaves), more closely related to the asparagus than to other trees. This desert dweller is an arborescent, or tree-like, species of yucca, characterized by its stout, shaggy trunk and a crown of spiky leaves. Unlike most trees, the Joshua Tree doesn’t have growth rings, making it difficult to determine their age. However, these trees can live for hundreds of years, with some ancient sentinels estimated to be over a millennium old. The tallest trees reach about 15 m (49 ft). New plants can grow from seed, but in some populations, new stems grow from underground rhizomes that spread out around the parent tree.

The Joshua tree is also known as izote de desierto (Spanish for “desert dagger”). It was first formally described in the botanical literature as Yucca brevifolia by George Engelmann in 1871 as part of the famous Geological Exploration of the 100th meridian (or “Wheeler Survey“).

The moniker “Joshua tree” is believed to originate from Mormon pioneers traversing the expanses of the Mojave Desert around the mid-1800s. They found the tree’s distinctive shape—with its limbs persistently outstretched—reminiscent of the biblical tale where Joshua extends his hands for a prolonged period, assisting the Israelites in their capture of Canaan, as recounted in the Book of Joshua. The tree’s tangled leaves also contributed to this image, giving it the semblance of a beard.

Nevertheless, this charming story lacks direct historical evidence from the period and the name “Joshua tree” doesn’t appear in records until after the Mormons had already settled in the area. Interestingly, the tree’s unique form may bear a stronger resemblance to narratives associated with Moses rather than Joshua. The absence of contemporary accounts leaves the true origin of the name enshrouded in the mystery of the past, adding to the tree’s allure and the folklore of the American West.

Joshua Trees burned in the 2020 Dome fire. (Photo: Erik Olsen)

The habitat of the Joshua Tree is as unforgiving as it is beautiful. They are found primarily in the Mojave Desert, the highest and coldest desert in the United States. These trees have adapted to the extremes, flourishing at elevations between 2,000 and 6,000 feet where the temperatures can plummet below freezing at night and soar during the day.

One of the most fascinating aspects of the Joshua Tree is its symbiotic relationship with the yucca moth. In a marvelous evolutionary dance, the moth is the tree’s sole pollinator, and in turn, the tree provides the moth a place to lay its eggs. This mutualistic relationship underscores the delicate balance of desert ecosystems.

Joshua Tree National Park was established as a national monument in 1936 and later upgraded to a national park in 1994, largely to protect the distinctive Joshua Trees and the unique desert ecosystem they epitomize. The effort to safeguard this landscape was driven by citizens and supporters who were passionate about the conservation of its otherworldly terrain and the diverse life forms that inhabit it.

Despite their hardy appearance, Joshua Trees harbor secrets that are only now being fully understood by scientists. Their root systems, for instance, can extend vertically to 30 feet and horizontally to 36 feet, a testament to their search for water in arid soils. Moreover, these trees are a keystone species, providing critical habitat for a host of desert organisms, from the Scott’s Oriole that nests in its branches to the black-tailed jackrabbit seeking shade under its canopy.

However, the stability of the Joshua Tree’s future is uncertain. Climate change poses a significant threat to its survival. Rising temperatures and altered precipitation patterns are projected to shrink the suitable habitat for Joshua Trees by up to 90% by the end of the century. Efforts are underway to understand and mitigate these impacts, with conservationists advocating for policies to reduce carbon emissions and protect the Joshua Tree’s habitat from development and resource exploitation.

In August 2020, a devastating blaze known as the Dome Fire swept through the Mojave National Preserve, scorching over 43,000 acres of one of the most extensive Joshua tree forests on the planet, located at Cima Dome. The inferno, which was one of the most destructive in recent history, decimated an estimated 1 million to 1.3 million Joshua trees, transforming a once thriving ecosystem into a haunting landscape of charred remains.

This catastrophic event not only altered the physical landscape but also raised urgent questions about the future of these iconic trees in the face of escalating climate change threats. The resilience of Joshua trees to fire is typically low, and the recovery of these forests could be severely hampered by the changing climate, with hotter, drier conditions becoming more common. The loss of these trees in such vast numbers is a stark reminder of the vulnerability of desert ecosystems and the need for immediate action to mitigate the impacts of climate change and protect these natural treasures for future generations.

Although California came out of drought in 2023, there is no guarantee that dry, hot conditions won’t continue. If they do, Joshua trees could lose 90 percent of their range by the end of the century, Dr. Cameron Barrows, a research ecologist with the University of California Riverside’s Center for Conservation Biology told Outside magazine.

The Joshua Tree’s importance to California’s landscape is indelible. It’s not only an ecological mainstay but also a cultural and historical icon, inspiring artists, musicians, and nature lovers alike. The trees’ spiky profiles are a testament to the unrivaled beauty of the American West.

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