Category: Geology and Earthquakes

The Plate Tectonic Revolution and How California Became the Epicenter of a Scientific Breakthrough

How the 1969 Penrose Conference on plate tectonics at Asilomar in California transformed our understanding of Earth’s dynamic processes.

Aerial photo of San Andreas Fault looking northwest onto the Carrizo Plain with Soda Lake visible at the upper left. (Wikipedia)
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Before the late 1960s, understanding Earth’s shifting surface, particularly in a geologically active region like California, was a major scientific challenge. For most of human history, the causes of earthquakes remained an enigma—mysterious and terrifying, often attributed to supernatural forces. In Japan, for example, earthquakes were traditionally believed to be caused by Namazu, a giant catfish said to live beneath the earth and whose thrashing would shake the land. Many societies believed earthquakes were divine punishments or omens, while others considered them an essential part of creation, events necessary to form a world habitable by us humans.

The complexity of California’s landscape, its mountains, valleys, deserts, and intricate network of faults, posed difficulties for early geologists. The land appeared chaotically interwoven, with many different types of rock making up the gaping deserts and soaring peaks. As the great University of California at Davis geologist Eldridge Moores once put it, “Nature is messy. Don’t expect it to be uniform and consistent.”

An image of humans battling a Namazu (Credit: Tokyo University Library. Public Domain)

But there was no overarching explanation for how these earthly features got there. Scientists could observe and record earthquakes, but without a unifying theory, they struggled to piece together the deeper mechanisms driving these powerful events.

This frustration lingered until the late 1960s when an intellectual revolution in geology took shape. Despite the dawn of the space age and the rise of computing power, many earth scientists still clung to the belief that the continents were fixed, immovable features on the Earth’s surface. The breakthrough came with the acceptance of plate tectonics—a theory that elegantly explained not just earthquakes, but the entire dynamic nature of Earth’s surface. And for many geologists, the moment this new understanding solidified was in December 1969, at a groundbreaking conference at the Asilomar Conference Center in California that reshaped the future of the field. (Notably, Asilomar was also the site of the historic 1975 conference on recombinant DNA, where scientists gathered to establish ethical guidelines for genetic research, an event we have explored previously.) This was the moment when plate tectonics, a concept that would fundamentally reshape our view of the planet, truly took hold in the Western American geological community.

At California’s Asilomar Conference Grounds, nestled amid Monterey pines and dramatic granite formations, scientists gathered to rewrite our understanding of tectonics—and reshape how we think about Earth’s restless surface. (Erik Olsen)

For centuries, explanations for Earth’s features ranged from catastrophic events to gradual uplift and erosion, a debate that became known as uniformitarianism versus catastrophism. In California, the sheer complexity of the geology, with its links go far beyond the borders of the state, hinted at powerful forces at play. Scientists grappled with the origins of the Sierra Nevada, the formation of the Central Valley, and the persistent threat of earthquakes along the now-famous San Andreas Fault. The prevailing models, however, lacked the comprehensive framework to connect these disparate observations into a coherent narrative.

The seeds of the plate tectonic revolution had been sown earlier in the 20th century with Alfred Wegener’s theory of continental drift. Anyone looking at a world map or globe could see how the coastlines of certain continents, particularly South America and Africa, seemed to fit together like pieces of a puzzle, suggesting they were once joined. Wegener proposed that the continents were once joined together in a supercontinent called Pangaea and had gradually drifted apart over millions of years. While his ideas were initially met with skepticism, particularly regarding the mechanism that could drive such massive movements, compelling evidence from paleontology, glacial geology, and the jigsaw-like fit of continental coastlines slowly began to sway opinions. The discovery of seafloor spreading in the 1960s (itself a great story, featuring the brilliant geologist and cartographer Marie Tharp) which revealed that new oceanic crust was constantly being generated at mid-ocean ridges and that the ocean floor itself was moving like a conveyor belt, provided the crucial mechanism Wegener lacked.

Heinrich Berann’s 1977 painting of the Heezen-Tharp “World Ocean Floor” map, a landmark in cartography that showed how the earths plates in some areas are pulling apart while others collide. (Library of Congress)

It was against this backdrop of burgeoning evidence that the Geological Society of America convened one of its annual Penrose Conferences in December 1969 at the Asilomar Conference Center in Pacific Grove, California. Titled “The Meaning of the New Global Tectonics,” the event drew structural geologists from all over the world.  The geological world changed overnight. A key figure in the conference was William R. Dickinson, a leading structural geologist whose work helped bridge the gap between traditional geological interpretations and the emerging plate tectonic framework. Dickinson’s research on sedimentary basins and tectonic evolution provided critical insights into how plate movements shaped the western United States, further solidifying the new theory’s acceptance.

These conferences were designed to be intimate gatherings where geologists could engage in focused discussions on cutting-edge research. The 1969 meeting proved to be a pivotal one. As UC Davis’ Moores, then a youthful figure who would become a leading voice of the “New Geology” in the West, later wrote, “the full import of the plate tectonic revolution burst on the participants like a dam failure”.

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)

Paper after paper presented at the conference demonstrated how the seemingly simple notion of large plates floating atop the Earth’s plastic mantle (the asthenosphere) could explain a vast array of geological phenomena. The location of volcanoes, the folding of mountains (orogeny), the distribution of earthquakes, the shape of the continents, and the history of the oceans all suddenly found a compelling and unified explanation within the framework of plate tectonics. Geologist John Tuzo Wilson famously referred to plate tectonics as ‘the dance of the continents,’ a phrase that captured the excitement and transformative nature of this intellectual breakthrough.

For Moores, the conference was a moment of profound realization. “It was a very exciting time. I still get goosebumps even talking about it,” he told the writer John McPhee. “A turning point, I think it was, in the plate tectonic revolution, that was the watershed of geology.” Moores had been contemplating the perplexing presence of ophiolite sequences – distinctive rock assemblages consisting of serpentines, gabbro/lava, and sediments – found high in the mountains of the West, including California. He suddenly grasped that these strange and “exotic” rock sequences were remnants of ancient ocean floors that had been lifted on top of the continent through the collision of tectonic plates.

Asilomar Conference Grounds Interior (Erik Olsen)

Moores reasoned that the serpentines and coarsely crystalline igneous rocks at the base of these sequences were characteristic of the rocks underlying all the world’s oceans. The “green rocks” in the middle (now the state rock of California) showed evidence of moderate pressure and temperatures, indicating they had been subjected to significant geological forces. By connecting these ophiolite sequences to the processes of plate collision and obduction (where one plate rides over another), Moores provided a powerful piece of evidence for plate tectonics and offered a new lens through which to understand the complex geological architecture of the American West.

His deduction was in line with what is now known about plate tectonics. The geological “confusion” apparent in the Rockies, the Sierra Nevada, and other western mountain chains was now understood as the result of neighboring plates bumping into each other repeatedly over vast geological timescales. The concept of terranes, foreign rock slabs or slices or sequences that have traveled vast distances and become accreted to continents, further illustrated the dynamic and assembly-like nature of California’s geological landscape.

Fault Activity Map of LA Area in California (California Geological Survey)
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California, situated at the active boundary between the massive Pacific Plate and the North American Plate, became a prime natural laboratory for studying the principles of plate tectonics. The San Andreas Fault, a “right-lateral strike-slip fault” where the Pacific Plate slides northward relative to the North American Plate, is a direct consequence of this ongoing tectonic interaction. Places like Parkfield, California, lying directly on the fault, became the center of the seismic universe, offering invaluable opportunities to study the processes of locking and unlocking that precede earthquakes.

The San Andreas Fault at Wallace Creek. On January 9, 1857, the M 7.9 Fort Tejon earthquake occurred just north of the Carrizo Plain. Here, at Wallace Creek, the fault moved 30 feet (9m), forming the offset stream channel seen in the photo. (USGS)

The dramatic offsets of streams like Wallace Creek on the Carrizo Plain vividly demonstrate the horizontal movement along the fault. These offsets, where streams appear abruptly displaced, serve as clear, visual records of the fault’s slip history, showing just how much the land has shifted over time. Further proof of the movement of plates along the fault was uncovered in a remarkable investigation by Thomas Dibblee Jr., a pioneering field geologist who meticulously mapped vast regions of California. One of his most compelling discoveries was the striking geological similarity between rocks found at Pinnacles National Park and those in the Neenach Volcanic Field, located more than 195 miles to the southeast. Dibblee determined that these formations were once part of the same volcanic complex but had been separated by the gradual (but pretty damn quick in geological time) movement of the Pacific Plate along the San Andreas Fault over millions of years.

The insights gained from the plate tectonic revolution, sparked in part by that pivotal conference in Pacific Grove, continue to inform our understanding of California’s geological hazards and history. The work of scientists like Eldridge Moores and the subsequent advancements in the field have provided a robust framework for interpreting the state’s complex and ever-evolving landscape. The 1969 Penrose Conference marked not just a shift in scientific thinking but a fundamental unlocking of some of the Earth’s deep secrets, with California the place, once again, at the center of scientific advance.

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Berkeley’s Cosmic Breakthrough and the Alvarez Discovery That Rewrote Earth’s History

Artist’s rendering of the colossal Chicxulub meteor hurtling toward Earth, moments before impact on the Yucatán Peninsula, an event that reshaped life on our planet 66 million years ago. (Erik Olsen)
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It is no coincidence that “Eureka” is the state motto of California. From its founding, the state has been a hub of groundbreaking discoveries, from the Gold Rush to advancements in space exploration, the rise of Silicon Valley and the development of modern computing, the development of seismic science, and the confirmation of the accelerating expansion of the universe. But one discovery made at the University of California, Berkeley, changed the way we see the world—or at least how it was almost destroyed, along with a huge part of life on the planet.

In 1977, Walter Alvarez arrived at Berkeley with rock samples from a small Italian town called Gubbio, unaware that they would help rewrite the history of life on Earth. He had spent years studying plate tectonics, but his father, Luis Alvarez, a Nobel Prize-winning physicist known for his unorthodox problem-solving at Berkeley, would propel him into a new kind of investigation, one deeply rooted in geology and Earth sciences. Their work led to one of the most significant scientific breakthroughs of the 20th century: the discovery that a massive meteorite impact was responsible for the extinction of the dinosaurs and much of life on Earth.

Luis and Walter Alvarez stand at the K–Pg boundary within the rock layers of a limestone outcrop near Gubbio, Italy, in 1981. This geological marker is linked to the asteroid impact that triggered the mass extinction 66 million years ago. (Lawrence Berkeley National Laboratory)

The samples Walter had collected contained a puzzling clay layer sandwiched between older and younger limestone deposits. This clay was rich in iridium—an element rare on Earth’s surface. The discovery of such an unusually high concentration of iridium in a single layer of buried rock was perplexing. Given that iridium is far more common in extraterrestrial bodies than on Earth’s surface, its presence suggested an extraordinary event—one that had no precedent in scientific understanding at the time. The implications were staggering: if this iridium had arrived all at once, it pointed to a cataclysmic event unlike anything previously considered in Earth’s history. Although some scientists had speculated about meteor impacts, solid evidence was scarce.

Alvarez determined that this layer corresponded precisely to the Cretaceous-Paleogene (K-Pg) boundary (formerly called Cretaceous–Tertiary or K–T boundary), the geological marker of the mass extinction that eradicated the non-avian dinosaurs 66 million years ago. Scientists had long debated the cause of this catastrophe, proposing theories ranging from volcanic activity to gradual climate change. But the Alvarez team would introduce a radical new idea—one that required looking beyond Earth.

Layers of sediment at Stevns Klint, Denmark, showcasing the distinct K–Pg boundary. The dark clay layer, rich in iridium, marks the asteroid impact that led to the mass extinction of the dinosaurs 66 million years ago. (UNESCO)

Mass extinctions stand out so distinctly in the fossil record that the very structure of geological time is based on them. In 1841, geologist John Phillips divided life’s history into three chapters: the Paleozoic, or “ancient life”; the Mesozoic, or “middle life”; and the Cenozoic, or “new life.” These divisions were based on abrupt breaks in the fossil record, the most striking of which were the end-Permian extinction and the end-Cretaceous extinction, noted here. The fossils from these three eras were so different that Phillips originally believed they reflected separate acts of creation. Charles Lyell, one of the founders of modern geology, observed a “chasm” in the fossil record at the end of the Cretaceous period, where species such as belemnites, ammonites, and rudist bivalves vanished entirely. However, Lyell and later Charles Darwin dismissed these apparent sudden extinctions as mere gaps in the fossil record, preferring the idea of slow, gradual change (known as gradualism, versus catastrophism). Darwin famously compared the fossil record to a book where only scattered pages and fragments of lines had been preserved, making abrupt transitions appear more dramatic than they were.

Luis Alvarez was a physicist whose career had spanned a remarkable range of disciplines, from particle physics to aviation radar to Cold War forensics. He had a history of bold ideas, from using muon detectors to search for hidden chambers in pyramids to testing ballistic theories in the Kennedy assassination with watermelons. When Walter shared his perplexing stratigraphic findings, Luis proposed a novel method to measure how long the clay layer had taken to form: by analyzing its iridium content.

A fossilized ammonite, one of many marine species that vanished at the K–Pg boundary, marking a sharp “chasm” in the fossil record after the asteroid impact 66 million years ago. (Photo: Erik Olsen)

As discusses, Iridium is a rare element on Earth’s surface but is far more abundant in meteorites. Luis hypothesized that if the clay had accumulated slowly over thousands or millions of years, it would contain only tiny traces of iridium from cosmic dust. But if it had been deposited rapidly—perhaps by a single catastrophic event—it might show an anomalously high concentration of the element. He reached out to a Berkeley colleague, Frank Asaro, whose lab had the sophisticated equipment necessary for this kind of analysis.

Nine months after submitting their samples, Walter received a call. Asaro had found something extraordinary: the iridium levels in the clay layer were off the charts—orders of magnitude higher than expected. No one knew what to make of this. Was it a weird anomaly, or something more significant? Walter flew to Denmark to collect some late-Cretaceous sediments from a set of limestone cliffs known as Stevns Klint. At Stevns Klint, the end of the Cretaceous period shows up as a layer of clay that’s jet black and contains high amounts of organic material, including remnants of ancient marine life. When the stinky Danish samples were analyzed, they, too, revealed astronomical levels of iridium. A third set of samples, from the South Island of New Zealand, also showed an iridium “spike” right at the end of the Cretaceous. Luis, according to a colleague, reacted to the news “like a shark smelling blood”; he sensed the opportunity for a great discovery.

Stevns Klint’s towering white chalk cliffs stand as a dramatic testament to Earth’s history, preserving the thin, dark Fish Clay layer that marks the cataclysmic asteroid impact that ended the age of dinosaurs 66 million years ago. (UNESCO)

The Alvarezes batted around theories. But all the ones they could think of either didn’t fit the available data or were ruled out by further tests. Then, finally, after almost a year’s worth of dead ends, they arrived at the impact hypothesis. On an otherwise ordinary day sixty-six million years ago, an asteroid six miles wide collided with the Earth. Exploding on contact, it released energy on the order of a hundred million megatons of TNT, or more than a million of the most powerful H-bombs ever tested. Debris, including iridium from the pulverized asteroid, spread around the globe. Day turned to night, and temperatures plunged. A mass extinction ensued. Even groups that survived, like mammals and lizards, suffered dramatic die-offs in the aftermath. Who perished, and who survived, set the stage for the next 66 million years—including our own origin 300,000 years ago.

The Alvarezes wrote up the results from Gubbio and Stevns Klint and sent them, along with their proposed explanation, to Science. “I can remember working very hard to make that paper just as solid as it could possibly be,” Walter later recalled. Their paper, Extraterrestrial Cause for the Cretaceous-Tertiary Extinction, was published in June 1980. It generated enormous excitement, much of it beyond the bounds of paleontology, but it was also ridiculed by some who considered the idea far-fetched, if not ridiculous. Journals in disciplines ranging from clinical psychology to herpetology reported on the Alvarezes’ findings, and soon the idea of an end-Cretaceous asteroid was picked up by magazines like Time and Newsweek. In an essay in The New York Review of Books, the late American paleontologist Stephen Jay Gould quipped that linking dinosaurs—long an object of fascination—to a major cosmic event was “like a scheme a clever publisher might devise to ensure high readership.”

Inspired by the impact hypothesis, a group of astrophysicists led by Carl Sagan decided to try to model the effects of an all-out war and came up with the concept of “nuclear winter,” which, in turn, generated its own wave of media coverage. But as the discovery sank in among many professional paleontologists, the Alvarezes’ idea—and in many cases, the Alvarezes themselves—were met with hostility. “The apparent mass extinction is an artifact of statistics and poor understanding of the taxonomy,” one paleontologist told The New York Times. “The arrogance.”

Skepticism was immediate and intense. Paleontologists, geologists, and physicists debated the implications of the iridium anomaly. But as the search for supporting evidence intensified, the pieces of the puzzle began to fall into place. Shocked quartz, a telltale sign of high-energy impacts, was found at sites around the world. Soot deposits suggested massive wildfires had raged in the aftermath.

Artists rendering of T-rex and other dinosaurs prior to the impact of the asteroid (Erik Olsen)

In the early 1990s, conclusive evidence finally emerged. The Chicxulub crater, measuring roughly 180 kilometers across and buried under about half a mile of sediment in Mexico’s Yucatán Peninsula, was identified as the likely impact site. Although it was first detected by Mexico’s state-run oil company (PEMEX) in the 1950s during geophysical surveys, core samples taken decades later clinched the identification of Chicxulub as the long-sought impact site linked to the mass extinction that ended the Cretaceous era.

One of the more intriguing (if not astounding) recent discoveries tied to the end-Cretaceous impact is a site called Tanis, located in North Dakota’s Hell Creek Formation. Discovered in 2019 by a team led by Robert DePalma and spotlighted in a New Yorker article, Tanis preserves a remarkable snapshot of what appears to be the immediate aftermath of the asteroid strike.

Tanis fossils (Image credit: Courtesy of Robert DePalma)

The sedimentary layers at Tanis indicate large waves—often called “seiche waves”—that may have surged inland in the immediate aftermath of the impact. They also contain countless tiny glass spherules that rained down after the explosion. Known as microtektites, these blobs form when molten rock is hurled into the atmosphere by an asteroid collision and solidifies as it falls back to Earth. The site appears to hold them by the millions. In some cases, fish fossils have been found with these glass droplets lodged in their gills—a striking testament to how suddenly life was disrupted.

Although still under investigation, Tanis has drawn attention for its exceptional level of detail, potentially capturing events that took place within mere hours of the impact. The precise interpretation of this site continues to spark controversy among researchers. There is also controversy about the broader cause of the mass extinction itself: the main competing hypothesis is that the colossal “Deccan” volcanic eruptions, in what would become India, spewed enough sulfur and carbon dioxide into the atmosphere to cause a dramatic climatic shift. However, the wave-like deposits, along with the abundant glass spherules, suggest a rapid and violent disturbance consistent with a massive asteroid strike. Researchers hope to learn more about the precise sequence of disasters that followed—tidal waves, intense firestorms, and global darkness—further fleshing out the story of how the world changed so drastically, so quickly.

Glass spherules from cosmic impacts—microtektites from Tanis, tiny relics of Earth’s violent encounters with space. (Image credit: Courtesy of Robert DePalma)

All said, today the Alvarez hypothesis is widely accepted as the leading explanation for the K-Pg mass extinction. Their contributions at UC Berkeley—widely recognized as one of the world’s preeminent public institutions—not only reshaped our understanding of Earth’s history but also changed how we perceive planetary hazards. The realization that cosmic collisions have shaped life’s trajectory has led to renewed interest in asteroid detection and planetary defense.

Walter and Luis Alvarez’s discovery was a testament to the power of interdisciplinary science and the willingness to follow unconventional ideas. Their pursuit of an extraterrestrial explanation for a terrestrial mystery reshaped paleontology, geology, and astrophysics. What began with a father and son pondering an ancient Italian rock layer ended in a revelation that forever changed how we understand the history of life—and its vulnerability to forces from beyond our world.

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Long Valley Caldera Discover the Science and Beauty of California’s Ancient Supervolcano

The Legacy of One of North America’s Largest Volcanic Eruptions

The Long Valley Caldera is one of the most active volcanic sites in the United States.
Here, the Owens River flows through it, winding south through Owens Valley. (Erik Olsen)
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Driving up Highway 395 toward Mammoth Lakes is one of the most breathtaking road trips in California. The highway winds through the rugged Eastern Sierra, offering stunning views of snow-capped peaks, alpine meadows, and vast chaparral plains. But beneath this dramatic landscape lurks a hidden danger—an ancient volcanic giant that still stirs beneath the surface.

The Long Valley Caldera in eastern California is an extraordinary geological feature, spanning about 20 miles in length and 11 miles in width. It owes its existence to one of the most dramatic volcanic events in Earth’s history, a supereruption that occurred approximately 760,000 years ago. This event, known as the Bishop Tuff eruption, ejected an estimated 150 cubic miles of molten rock and ash into the atmosphere, far surpassing the 1980 eruption of Mount St. Helens, which released just 0.3 cubic miles of material. The magnitude of the Bishop Tuff eruption resulted in the collapse of the ground above the magma chamber, creating a massive depression known as a caldera. In other words, it’s hard to get your head around how big this eruption was.

The Long Valley Caldera is a striking reminder of Earth’s immense, often hidden, volcanic power and its potential for destruction—located right here in California, near one of the nation’s most popular ski towns, Mammoth Lakes. Geothermal activity, visible in the form of hot springs, fumaroles, and hydrothermal systems, is a constant feature of the landscape. This activity has made the caldera a hub for geothermal energy production, with the Casa Diablo thermal power plant utilizing its subterranean heat to generate electricity. The energy produced at Casa Diablo is enough to power about 36,000 homes, making it an important renewable energy source for the region.

Casa Diablo Geothermal Facility, Long Valley Caldera, California (Erik Olsen)
Casa Diablo Geothermal Facility, Long Valley Caldera, California (Erik Olsen)

The surface of the caldera is also marked by the Bishop Tuff, a layer of welded volcanic ash that provides a vivid record of the eruption’s intensity and the pyroclastic flows that reshaped the landscape. Pyroclastic flows are fast-moving, hot clouds of gas and volcanic material that can destroy everything in their path. Often they are considered more dangerous than the lava that pours forth from an erupting volcano. For example, pyroclastic flows killed far more people at Pompeii than lava, as the 79 AD eruption of Mount Vesuvius unleashed fast-moving clouds of superheated gas, ash, and volcanic debris that raced down the slopes at over 100 mph, reaching temperatures above 1,000°F, instantly asphyxiating and incinerating thousands, while the slower-moving lava played a minimal role in fatalities.

Geothermal features at the Long Valley Caldera commonly support microbial communities of thermophilic bacteria and algae, which thrive in the caldera’s hot springs and fumaroles. These organisms not only influence the terrain by contributing to mineral precipitation but also serve as models for studying life in extreme environments, offering analogs for early Earth and potential extraterrestrial ecosystems. Scientists are just beginning to understand how these bacteria live and thrive in deep ocean vent systems. In some areas around the Long Valley Caldera and Mono Lake, mats of thermophilic bacteria and algae thrive around the geothermal features, like the many hot tubs that dot the landscape, forming colorful, textured surfaces. These microbial communities contribute to the unique environment and can even make the ground feel crunchy underfoot, offering a tangible connection to the caldera’s dynamic, living systems.

The Owens River flows through the Long Valley Caldera near Mammoth Lakes, California (Erik Olsen)

While the caldera’s formation was sudden and catastrophic, its story stretches back millions of years. Scientific studies at the Long Valley Caldera have advanced our understanding of volcanic processes, crustal dynamics, and geothermal systems. The Long Valley Caldera sits within the Basin and Range Province, an area of North America characterized by extensional tectonics, where the Earth’s crust is being pulled apart, allowing magma to rise to the surface.

Using seismic tomography, researchers have mapped the magma chamber beneath the caldera, revealing a layered structure with a partially molten zone capped by solidified magma. This configuration, as highlighted in a 2023 study published in Science Advances, helps explain the periodic episodes of unrest observed in the caldera and provides a basis for assessing potential future activity. Before the eruption, the region experienced significant volcanic activity, with lava flows and smaller eruptions setting the stage for what was to come. Even after the formation of the caldera, volcanic activity continued in the area. Rhyolitic lava flows emerged within the caldera, and the nearby Mono-Inyo Craters volcanic chain has seen eruptions as recently as 600 years ago, underscoring the region’s enduring geological vitality.

Horseshoe Lake in the Mammoth Lakes area, where underground carbon dioxide emissions have caused widespread tree die-off
(Photo: Erik Olsen)

Another place where the region’s volcanic activity can be experienced firsthand is Horseshoe Lake, where carbon dioxide continuously seeps from the ground, suffocating tree roots and causing a vast die-off of trees. The result is a barren, almost ghostly landscape of skeletal trunks and lifeless ground, a stark reminder that Long Valley’s volcanic system is still active beneath the surface. The area is not just eerie but also hazardous—high concentrations of CO₂ can accumulate in low-lying areas, posing a serious risk to humans and animals. Signs around the site warn visitors of the danger, as pockets of odorless, colorless gas can be lethal if inhaled in high enough doses.

Hot Springs geological site near Mammoth Lakes, California. (Erik Olsen)

The caldera has not been entirely quiet since its dramatic birth. Ground deformation studies, using GPS and InSAR technology (satellites), have tracked uplift in the caldera’s floor, offering critical data on magma movement and hydrothermal activity. In a 2016 study published in Geophysical Research Letters, researchers linked changes in uplift patterns to deeper magmatic processes, reinforcing the importance of continuous monitoring. In 1980, a series of magnitude 6 earthquakes occurred along its southern margin, drawing the attention of volcanologists from USGS. These earthquakes were accompanied by noticeable uplift in the caldera’s floor, a sign of magma movement beneath the surface. Since then, the region has experienced periodic episodes of ground deformation and seismic activity, reminding scientists that the volcanic system beneath Long Valley is far from dormant.

Recent research has provided valuable insights into the caldera’s potential for future activity. While there is currently no indication of an imminent eruption, the area is closely monitored by the United States Geological Survey (USGS). This surveillance includes the measurement of ground deformation, gas emissions, and seismic activity, all of which serve as indicators of changes within the magma chamber. The 1980s unrest heightened awareness of the need for vigilance, particularly in regions where volcanic hazards could affect human populations.

Mono Lake is home to thermophilic (heat-loving) and extremophilic (extreme-condition-loving) bacteria. These microorganisms thrive in the lake’s unusual environment, characterized by high alkalinity, high salinity, and elevated levels of carbonate. (Erik Olsen)

As a result of these studies, the town of Mammoth Lakes took proactive measures to ensure public safety. Local authorities constructed an emergency evacuation route to serve as an escape in the event of a volcanic eruption or other natural disaster stemming from the Long Valley Caldera. After local businesses and residents expressed concerns that the original name implied danger, it was changed to Mammoth Scenic Loop to emphasize the area’s beauty and appeal. The United States Geological Survey (USGS) also intensified its monitoring efforts, implementing a color-coded alert system to communicate volcanic activity risks.

Beyond its scientific significance, the Long Valley Caldera is a destination for outdoor enthusiasts and other researchers. Numerous hot springs dot the landscape and are immensely popular among tourists and residents. Mammoth Lakes is one of California’s top recreational spots, providing amazing opportunities to hike and fish during the summer and excellent skiing in the winter months. For geologists, the caldera serves as a natural laboratory, providing an opportunity to study volcanic processes in a setting shaped by one of the most powerful eruptions in recent geological history.

The eastern Sierra reflected in Little Alkali Lake near the Long Valley Caldera (Erik Olsen)

Of course, there remain certain dangers to all this volcanic activity. On April 6, 2006, three members of the Mammoth Mountain ski patrol tragically lost their lives after falling into a volcanic fumarole near the summit. The incident happened while they were conducting safety operations to secure a snow-covered geothermal vent following an unprecedented snowfall. If you’ve ever skied Mammoth before, there is a distinct sulphurous smell around the Christmas Bowl ski run at Chair 3 near McCoy Station.

Steam from an active fumarole near McCoy Station on Mammoth Mountain in 2012. (Flickr)

Standing at the center of the Long Valley Caldera, surrounded by the remnants of a prehistoric supereruption, offers a profound sense of scale and wonder. The vastness of the caldera, framed by the Sierra Nevada and dotted with geothermal vents, creates a landscape that feels alive yet ancient. It’s amazing place to be, both during the day and at night when the stars spread out across the gaping Sierra sky. The ground beneath your feet, shaped by cataclysmic forces, whispers of Earth’s power and the quiet persistence of geological time. Yet beneath the surface, the processes that shaped it continue to evolve, as magma slowly shifts and geothermal systems release heat from the planet’s interior. As research continues and technology advances, the Long Valley Caldera will undoubtedly yield further insights into the intricate workings of our planet’s volcanic systems.

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A Deep Dive into Monterey Canyon, California’s Great Abyss


Monterey Canyon stretches nearly 95 miles out to sea, plunging over 11,800 feet into the depths—one of the largest submarine canyons on the Pacific Coast, hidden beneath the waves. (Courtesy: Monterey Bay Aquarium Research Institute MBARI)
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Standing in Moss Landing, a small coastal town known for its fishing fleet, busy harbor, and the twin smokestacks of its power plant, it’s hard to imagine that just offshore lies one of the most dramatic geological features on the West Coast, hidden beneath the water. I’ve been to the town many times (Phil’s Fish Market & Eatery is no longer there, unfortunately, but The Power Plant Coffee is nice), and I always enjoy how quiet and old-fashioned it feels, like a glimpse of California from 30 years ago. Most people passing through probably have no idea that beyond the harbor, the seafloor suddenly drops away into a vast underwater canyon.

Monterey Canyon is one of the largest submarine canyons on Earth. It stretches roughly 95 miles into the Pacific and plunges more than 11,800 feet at its deepest point. In scale it rivals the Grand Canyon, but almost all of it lies out of sight beneath Monterey Bay.

Drifting through the depths of Monterey Canyon, the elusive barreleye fish reveals its transparent head and tubular eyes—an evolutionary marvel perfectly adapted to the dark, mysterious waters off Monterey Bay.
(Courtesy: Monterey Bay Aquarium Research Institute MBARI)

Monterey Canyon’s immense scale is the result of millions of years of underwater erosion. Powerful turbidity currents, dense flows of sand and sediment racing down the continental slope, have slowly carved the canyon and carried its debris far into the deep Pacific. One prevailing theory how it formed is that the canyon began as a river channel carved by the ancestral Salinas River, which carried sediments from the ancient Sierra Nevada to the ocean. As sea levels fluctuated during ice ages, the river extended further offshore, deepening the canyon through erosion. Another idea points to tectonic activity along the Pacific Plate as an important influence. Movement along nearby faults helped shape the seafloor and surrounding landscape, while gradual sinking of the continental shelf allowed sediment to collect and periodically cascade down the canyon into deeper water. These forces, combined with powerful turbidity currents, underwater landslides of sediment-laden water, worked in tandem to sculpt the dramatic contours we see today.

While the geology is awe-inspiring, the biology of Monterey Canyon makes it a living laboratory for scientists. The canyon is teeming with life, from surface waters to its darkest depths. Near the top, kelp forests and sandy seafloors support a wide variety of fish, crabs, and sea otters, while the midwater region, known as the “twilight zone,” is home to bioluminescent organisms like lanternfish and vampire squid that generate light for survival. Lanternfish use bioluminescence to attract prey and confuse predators, while vampire squid use light-producing organs to startle potential predators or escape into the deep. In the canyon’s deepest reaches, other bizarre creatures thrive in extreme temperature and pressure, including the gross-looking Pacific hagfish and the bizarre gulper eel. Some communities around cold seeps on the seafloor are sustained by chemical energy (chemosynthesis). Microbes feed on methane and other chemicals seeping from the sediments, supporting ecosystems of clams, bacterial mats, and, occasionally, tube worms.

A vampire squid (Vampyroteuthis infernalis) observed by MBARI’s remotely
operated vehicle (ROV) Tiburon in the outer Monterey Canyon at a depth of approximately
770 meters. (Courtesy: Monterey Bay Aquarium Research Institute MBARI)

The barreleye fish, captured in stunning video footage by MBARI, is one of the canyon’s most fascinating inhabitants. This deep-sea fish is known for its domed transparent head, which allows it to rotate its upward-facing eyes to track prey and avoid predators. Its unique adaptations are a dazzling product of evolution in deep water conditions, and only in recent decades have we developed the technology to explore the ocean this way and see these animals in their natural environment.

The canyon’s rich biodiversity depends on upwelling currents that draw cold, nutrient-rich water to the surface, triggering plankton blooms that sustain a complex food web. This process is vital in California waters, where it supports an astonishing array of marine life, from deep-sea creatures to surface animals like humpback whales, sea lions, and albatrosses.

A woolly siphonophore (Apolemia lanosa) observed by MBARI’s remotely
operated vehicle (ROV) Tiburon in the outer Monterey Canyon at a depth of 1,200 meters.
(Courtesy: Monterey Bay Aquarium Research Institute MBARI)

What sets Monterey Canyon apart is the sheer accessibility of this underwater frontier for scientific exploration. The canyon’s proximity to the shore makes it a prime research site for organizations like the Monterey Bay Aquarium Research Institute (MBARI). Using remotely operated vehicles (ROVs) and advanced oceanographic tools, MBARI scientists have conducted groundbreaking studies on the canyon’s geology, hydrology, and biology. Their research has shed light on phenomena like deep-sea carbon cycling, the behavior of deepwater species, and the ecological impacts of climate change.

They recently developed this animation, the most detailed ever created of Monterey Canyon, to show what it looks like below the surface. It combines ship-based multibeam data at a resolution of 25 meters (82 feet) with high-precision autonomous underwater vehicle (AUV) mapping data at just one meter (three feet), revealing the canyon’s intricate underwater topography like no one has ever seen before.

MBARI’s founder, the late David Packard, envisioned the institute as a hub for pushing the boundaries of marine science and engineering. Researchers like Bruce Robison have pioneered the use of ROVs to study elusive mid-water and deep-sea animals, capturing stunning footage of animals like the giant siphonophore, a colonial organism that can stretch over 100 feet, making it one of the longest animals on Earth.

Bruce Robison, deep-sea explorer and senior scientist at MBARI, has spent decades uncovering the mysteries of the ocean’s twilight zone, revealing the hidden lives of deep-sea creatures in Monterey Canyon. (Photo: Erik Olsen)

Among the younger generations of pioneering researchers at MBARI, Kakani Katija stands out for her groundbreaking contributions to marine science. Katija has spearheaded the development of FathomNet, an open-source image database that leverages artificial intelligence to identify and count marine animals in deep-sea video footage, revolutionizing how researchers analyze vast datasets.

Two leading scientists at MBARI, Steve Haddock and Kyra Schlining, have made groundbreaking discoveries in Monterey Canyon, expanding our understanding of deep-sea ecosystems. Haddock, a marine biologist specializing in bioluminescence, has revealed how deep-sea organisms like jellyfish and siphonophores use light for communication, camouflage, and predation. His research has uncovered new species and illuminated the role of bioluminescence in the deep ocean. Schlining, an expert in deep-sea video analysis, has played a key role in identifying and cataloging previously unknown marine life captured by MBARI’s remotely operated vehicles (ROVs). Her work has helped map the canyon’s biodiversity and track environmental changes over time, offering important clues about how human activity is affecting the ocean and how marine ecosystems respond.

A peacock squid (Taonius sp.) observed by one of MBARI’s remotely operated
vehicles. (Courtesy: Monterey Bay Aquarium Research Institute MBARI)

Monterey Canyon draws scientists from around the world. Its deep, steep walls and easy access from shore make it an ideal place to test new technologies, from autonomous underwater vehicles to instruments that track subtle changes in ocean chemistry. The canyon also feeds into a larger culture of ocean exploration here, with places like the Monterey Bay Aquarium helping translate what scientists discover in the deep into stories the public can see and understand.

As scientists push deeper into Monterey Canyon, right off our own coast, each expedition reveals something new. Strange animals, shifting sediments, and clues about how this hidden world works. But the more we learn, the more questions emerge about how life survives in the deep and how human activity may be changing it. With every dive, the canyon reminds us how much of the ocean remains unexplored.

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The Mountain Pass Mine in California May Be the U.S. Rare Earths Game Changer

A California Company Called MP Materials Hopes to Revitalize Domestic Rare Earth Production to Reduce Dependence on China

MP Materials Rare Earths Mine in Mountain Pass, California (Photo: Erik Olsen)
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Rare earth metals are now essential to the global economy, powering everything from smartphones and electric vehicles to wind turbines and defense systems. As China continues to dominate the market—producing more than 70% of the world’s supply—the urgency to find reliable alternatives has grown. The United States is locked in a high-stakes race to secure new sources of rare earth elements, along with other critical minerals like lithium and nickel, which are key to the clean energy transition. At the center of this effort is a storied mine in California that not only helped launch the rare earth industry decades ago but now stands as America’s most promising hope for rebuilding a domestic supply chain.

Mining shaped California’s growth, from the 1849 Gold Rush to key industries like mercury, silver, copper, tungsten, and boron. While some have declined, others, like the Rio Tinto U.S. Borax Mine in Boron, California, remain major global suppliers, while rare earth element extraction continues to be an important industry.

MP Materials’ Mountain Pass rare earths mine in California is a remarkable example of industrial resurgence and the strategic importance of critical metals in the modern era. Located in Mountain Pass in the remote Californian desert near the Nevada border (it’s easily viewable from Interstate 15), this mine, initially developed in the mid-20th century, has seen dramatic shifts in fortune, technology, and geopolitics, reflecting the complex role rare earth elements (REEs) play in global industries.

The rock at Mountain Pass contains an average of 7 to 8 percent rare earth elements—a remarkably high concentration by industry standards. This richness is a key factor in the mine’s potential. However, extracting these valuable elements from the surrounding material remains a challenge.

Discovered in 1949 while prospectors searched for uranium, the Mountain Pass deposit instead revealed bastnaesite, an ore rich in rare earth elements like neodymium, europium, and dysprosium. These elements are indispensable to modern technologies, powering innovations across consumer electronics, environmental solutions, and advanced military systems.

A computer-controlled arm deposits the raw crushed ore into a mound at the MP Materials mine and ore processing
site in Mountain Pass, CA. (Courtesy: MP Materials)

Smartphones, for instance, are packed with rare earth elements that enable their functionality. Europium and gadolinium enhance the brightness and color of their screens. Lanthanum and praseodymium contribute to the efficiency of their circuits, while terbium and dysprosium enable the compact, high-performance speakers. Beyond smartphones, rare earth elements are essential to electric vehicles and renewable energy technologies, particularly in the production of permanent magnets. Thanks to their distinctive atomic structure, rare earth elements can produce magnetic fields far stronger than those generated by other magnetizable materials like iron. This exceptional capability arises from their partially filled 4f electron shell, which is shielded by outer electrons. This configuration not only gives them unique magnetic properties but also results in complex electronic arrangements and a tendency for unpaired electrons with similar spins. These characteristics make rare earth elements indispensable for creating the most advanced and powerful commercial magnets, as well as for applications in cutting-edge electronics.

Permanent magnets are among the most significant uses of rare earths, as they convert motion into electricity and vice versa. In the 1980s, scientists discovered that adding small amounts of rare earth metals like neodymium and dysprosium to iron and boron created incredibly powerful magnets. These magnets are ubiquitous in modern technology: tiny ones make your phone vibrate, medium-sized ones power the wheels of electric cars, and massive ones in wind turbines transform the motion of air into electricity. A single wind turbine can require up to 500 pounds of rare earth metals, highlighting their critical role in reducing greenhouse gas emissions.

MP Materials Processing Facility in Mountain Pass, California (Courtesy: MP Materials)

Additionally, rare earths play a significant role in environmental applications. Cerium is used in catalytic converters to reduce vehicle emissions, while lanthanum enhances the efficiency of water purification systems. Rare earth-based phosphors are employed in energy-efficient lighting, such as LED bulbs, which are central to reducing global energy consumption.

The importance of these elements underpins the strategic value of deposits like Mountain Pass, making the extraction and refinement of rare earths a critical aspect of both technological progress and national security. In the military domain, rare earths are integral to cutting-edge systems. They are used in the production of advanced lasers, radar systems, night vision equipment, missile guidance systems, and jet engines. According the the Department of Defense, for example, the F-35 Lightning II aircraft requires more than 900 pounds of rare earth elements. Alloys containing rare earth elements also strengthen armored vehicles, while lanthanum aids in camera lenses and night vision optics, giving military forces a strategic advantage.

Bastnaesite concentrate. Bastnaesite is a mineral that plays a crucial role in the production of rare earth metals.
(Courtesy of MP Materials)

To fully appreciate the significance of rare earth elements and their crucial role in the United State’s economic future, it’s essential to explore the history of Mountain Pass, one of the most important rare earth mines in the world. This storied site not only played a pivotal role in meeting the surging demand for these elements but also serves as a case study in the challenges of balancing industrial ambition with environmental responsibility.

The Molybdenum Corporation of America, later renamed Molycorp, initially capitalized on the booming demand for europium in color televisions during the 1960s. In 1952, the company acquired the Mountain Pass site, recognizing its rich deposits of rare earth minerals. As the first major player in rare earths in the United States, it began operations at Mountain Pass, establishing a foothold in the burgeoning industry. Over the ensuing decades, Mountain Pass became the world’s premier source of rare earths, serving a growing market for advanced materials.

By the 1990s, however, the mine faced significant challenges. Environmental damage caused by leaks of heavy metals and radioactive wastewater led to regulatory scrutiny and costly fines, culminating in the mine’s closure. During its dormancy, global rare earth production shifted overwhelmingly to China, which gained near-monopoly control over the market. By the time Molycorp attempted to revive the site in the early 2000s, it struggled against operational inefficiencies, low rare earth prices, and fierce Chinese competition. Molycorp eventually declared bankruptcy, leaving the mine idle once again.

MP Materials Mine Facility (Photo: Erik Olsen)

In 2017, MP Materials, led by investors including Michael Rosenthal and Jim Litinsky, acquired the shuttered Mountain Pass mine after recognizing its untapped potential. Initially, they anticipated an established mining or strategic buyer would emerge. Faced with the risk of losing the mine’s permit and seeing it permanently closed through reclamation, they made the bold decision to operate it themselves. To restart operations, MP Materials partnered with Shenghe Resources, a Chinese state-backed company that provided critical early funding and became the company’s primary customer. Through this arrangement, MP shipped raw rare earth concentrate to China for processing, laying the foundation for a business model that was heavily reliant on the Chinese supply chain.

Over the next several years, Mountain Pass far exceeded expectations. By 2022, it was producing 42,000 metric tons of rare earth oxides—three times the best output achieved under its previous owner, Molycorp—and accounted for about 15% of global production. In 2024, the mine hit a U.S. production record with over 45,000 metric tons of REO in concentrate. But even as the mine’s output surged, MP Materials’ ties to China remained central to its operations. Shenghe not only purchased the bulk of that concentrate but also maintained an 8% ownership stake. In 2024, roughly 80% of MP’s revenue came from this relationship. That changed in 2025, when China imposed steep tariffs and new export restrictions. MP responded by halting all shipments to China, shifting instead to processing much of its output domestically and selling to U.S.-aligned markets like Japan and South Korea. It has since invested nearly $1 billion to build out a full domestic supply chain and launched a joint venture with Saudi Arabia’s Ma’aden, marking a decisive pivot away from reliance on China.

The processing of rare earth elements, particularly for high-value applications like magnets, involves a complex, multi-step value chain. It begins with extraction, where ores containing rare earths are mined, followed by beneficiation, a process that concentrates the ore to increase its rare earth content. Next, separation and refining isolate individual rare earth oxides through solvent extraction or other chemical methods. These refined oxides then undergo metallization, where they are reduced into their metallic form, making them suitable for further industrial use. The metals are then alloyed with other elements to enhance their properties, and finally, the material is shaped into high-performance magnets essential for applications in electric vehicles, wind turbines, and advanced electronics. Each of these steps presents significant technical, economic, and environmental challenges, making rare earth processing one of the most intricate and strategically important supply chains in modern technology.

Bastnaesite ore (Wikipedia)

Despite MP Materials’ success and efforts to ramp up facets of processing at its Mountain Pass mine in California, a critical portion of the rare earth refining process—metallization, alloying, and magnet manufacturing—remains dependent on other countries, including China and Japan. These procedures are both intricate and environmentally taxing, and California’s stringent regulatory framework, designed to prioritize environmental protections, has made domestic processing particularly challenging. Across the rare earths industry, this dependence on Chinese facilities exposes a significant vulnerability in the rare earth supply chain, leaving the United States and other countries reliant on foreign infrastructure to produce critical materials essential for technologies such as electric vehicles and advanced military systems.

However, to address the dependency on foreign processing, MP Materials is investing heavily in building a fully domestic rare earth supply chain. At its Mountain Pass mine in California, the company is enhancing its processing and separation capabilities to refine rare earth elements on-site. Meanwhile, at its new Independence facility in Fort Worth, Texas, MP Materials has begun producing neodymium-praseodymium (NdPr) metal and trialing sintered neodymium-iron-boron (NdFeB) magnets. This facility marks the first domestic production of these critical materials in decades, with the capability to produce 1,000 metric tons of magnets annually, amounting to the production of roughly half a million EV motors.

“This is our ultimate goal,” says Matt Sloustcher, EVP of Corporate Affairs for MP Materials. “To handle the entire separation and refining process on-site—but that ramp-up takes time.”

Individual slings of PrNd Oxide, the primary product produced at MP Materials. (Courtesy: MP Materials)

MP Materials asserts that the new U.S.-based rare earth supply chain it is developing will be a “zero discharge” facility, recycling all water used on-site and disposing of dry waste in lined landfills. That will make it a far more environmentally sustainable than its counterparts in Asia, where rare earth mining and processing have led to severe pollution and ecological damage. The company says it is making progress. MP Materials’ Sloustcher pointed California Curated to a Life Cycle Assessment (LCA) study published in the American Chemical Society which “found that NdFeB magnets produced from Mountain Pass ore have about one-third the environmental footprint of those from Bayan Obo, China’s largest rare earth mine.”

“With record-setting upstream and midstream production at Mountain Pass and both metal and magnet production underway at Independence , we have reached a significant turning point for MP and U.S. competitiveness in a vital sector,” said James Litinsky, Founder, Chairman, and CEO of MP Materials in a company release.

Interior view of the Water Treatment Plant at the MP Materials mine and ore processing site in
Mountain Pass, CA. (Courtesy: MP Materials)

MP Materials has also partnered with General Motors to produce rare earth magnets for electric vehicles, signaling its commitment to integrating domestic production into key industries. The push for domestic EV production is not just about economic security but also about environmental sustainability, as reducing the carbon footprint of mining, processing, and transportation aligns with the broader goal of clean energy independence.

The resurgence of the Mountain Pass mine aligns with a broader initiative by the U.S. government to secure domestic supplies of critical minerals. Recognizing Mountain Pass as a strategic asset, the Department of Defense awarded MP Materials a $35 million contract in February 2022 to design and build a facility for processing heavy rare earth elements at the mine’s California site Additionally, the Department of Energy has been actively supporting projects to strengthen the domestic supply chain for critical minerals, including rare earth elements, through various funding initiatives.

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Mountain Pass’s operations, however, highlight the challenges inherent in mining rare earths. The extraction process involves significant environmental risks, particularly in managing wastewater and tailings ponds. MP Materials claims to prioritize sustainable practices, yet its long-term ability to minimize environmental impact while scaling production remains under scrutiny. The mine’s bastnaesite ore, with rare earth concentrations of 7–8%, is among the richest globally, making it economically competitive. Still, as mentioned above, processing bastnaesite to isolate pure rare earth elements involves complex chemical treatments, underscoring why global production remains concentrated in a few countries.

Overhead view of the Crusher at the MP Materials mine and ore processing site in Mountain Pass, CA. (Courtesy: MP Materials)

Today, Mountain Pass is not only a critical supplier but also a symbol of U.S. efforts to reduce dependency on Chinese rare earth exports as well as other minerals such as lithium and copper vital to a transition to clean energy technology. As demand for REEs surges with advancements in green energy and technology, the increasing mine’s output supports the production of permanent magnets used in electric motors, wind turbines, and countless other applications. This resurgence in domestic rare earth production offers hope for a revitalized U.S.-based supply chain, reducing dependence on foreign sources and ensuring a more stable, sustainable future for critical mineral access.

However, significant obstacles remain, including the environmental challenges of mining, the high costs of refining and processing, and the need to develop advanced manufacturing infrastructure. Overcoming these barriers will require coordinated efforts from industry, government, and researchers to make domestic production both economically viable and environmentally responsible, ensuring a truly climate-friendly future. With the global race for critical minerals intensifying, MP Materials’ success demonstrates the potential—and challenges—of revitalizing domestic mining infrastructure in an era of heightened resource competition.

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Walter Munk was a Californian Oceanographer Who Changed Our Understanding of the Seas

Photo: Erik Jepsen (UC San Diego)
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Walter Munk, often referred to as the “Einstein of the Oceans,” was one of the most influential oceanographers of the 20th century. Over a career that spanned more than 70 years, Munk fundamentally altered how we think about the oceans, contributing to our understanding of everything from wave prediction during World War II to deep-sea drilling in California. His work at the Scripps Institution of Oceanography in La Jolla, California, was groundbreaking and continues to influence scientific thinking to this day.

Walter Heinrich Munk was born in Vienna, Austria, on October 19, 1917. At 14, he moved to New York, where he later pursued physics at Columbia University. He became a U.S. citizen in 1939 and earned a bachelor’s degree in physics from the California Institute of Technology the same year, followed by a master’s in geophysics in 1940. Munk then attended the Scripps Institution of Oceanography and completed his Ph.D. in oceanography from the University of California in 1947.

Dr. Walter Munk in 1952. (Scripps Institution of Oceanography Archives/UC San Diego Libraries)

In the early 1940s, Munk’s career took a defining turn when the United States entered World War II. At the time, predicting ocean conditions was largely guesswork, and this posed a significant challenge for military operations. Munk, a PhD student at Scripps at the time, was recruited by the U.S. Army to solve a problem that could make or break military strategy—accurate wave prediction for amphibious landings.

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One of his most famous contributions during the war came in 1944, ahead of the Allied invasion of Normandy. Alongside fellow oceanographer Harald Sverdrup, Munk developed a method to predict the size and timing of ocean waves, ensuring that troops could land safely during the D-Day invasion. Using their model, the Allied forces delayed the invasion by one day, a move that proved crucial in reducing casualties and securing the beachhead. This same wave prediction work was used again in the Pacific theater, particularly for landings on islands like Iwo Jima and Eniwetok. Munk’s contributions not only helped win the war but also laid the foundation for modern oceanography. Wave forecasting is now a standard tool for naval operations, shipping, and even recreational surfers.

Landing craft pass supporting warships in the Battle of Eniwetok, 19 February 1944. (U.S. Army)

After the war, Munk returned to Scripps, a place that would remain central to his career. Established in 1903, Scripps had been growing into a major center for oceanographic research, and Munk’s work helped elevate it to new heights. Located in La Jolla, just north of San Diego, Scripps was perfectly positioned on the California coastline to be at the forefront of oceanographic studies. Scripps is one of the premier oceanographic institutions in the world.

During the post-war years, Munk helped pioneer several new areas of research, from the study of tides and currents to the mysteries of the deep sea. California, with its rich marine ecosystems and coastal access, became the perfect laboratory. In La Jolla, Munk studied the Southern California Current and waves that originated across the Pacific, bringing new understanding to local coastal erosion and long-term climate patterns like El Niño. His research had a direct impact on California’s relationship with its coastline, from naval operations to public policy concerning marine environments.

Walter Munk in 1963 with a tide capsule. The capsule was dropped to the seafloor to measure deep-sea tides before such measurements became feasible by satellite. Credit Ansel Adams, University of California

While Munk’s contributions to wave forecasting may be his most widely recognized work, one of his boldest projects came in the 1960s with Project Mohole. It was an ambitious scientific initiative to drill into the Earth’s mantle, the layer beneath the Earth’s crust. The project was named after the Mohorovičić Discontinuity (named after the pioneering Croatian seismologist Andrija Mohorovičić), the boundary between the Earth’s crust and mantle. The boundary is often referred to as the “Moho”. The goal was revolutionary: to retrieve a sample from the Earth’s mantle, a feat never before attempted.

The idea was to drill through the ocean floor, where the Earth’s crust is thinner than on land, and reach the mantle, providing geologists with direct insights into the composition and dynamics of our planet. The project was largely conceived by American geologists and oceanographers, including Munk, who saw this as an opportunity to leapfrog the Soviet Union in the ongoing Cold War race for scientific supremacy.

The Glomar Challenger, launched in 1968, was the drill ship for NSF’s Deep Sea Drilling Project. (Public Domain)

California was again the backdrop for this audacious project. The drilling took place off the coast of Guadalupe Island, about 200 miles from the Mexican coast, and Scripps played a key role in organizing and coordinating the scientific work. The project succeeded in drilling deeper into the ocean floor than ever before, reaching 600 feet into the seabed. However, funding issues and technical challenges caused the U.S. Congress to abandon the project before the mantle could be reached. Despite its early end, Project Mohole is considered a precursor to modern deep-sea drilling efforts, and it helped pave the way for initiatives like the Integrated Ocean Drilling Program, which continues to explore the ocean’s depths today. For example, techniques for dynamic positioning for ships at sea were largely developed for the Mohole Project.

Munk’s work was deeply tied to California, a state whose coastlines and oceanography provided a wealth of data and opportunities for study. Scripps itself is perched on a stunning bluff overlooking the Pacific Ocean, a setting that greatly inspired Munk and his colleagues. Throughout his career, Munk worked on understanding the coastal dynamics of California, from studying the erosion patterns of beaches to analyzing how global warming might impact the state’s famous coastal cliffs.

Scripps Institution of Oceanography

His legacy continues to shape how California manages its vast coastline. The methodologies and insights he developed in wave prediction are now used in environmental and civil engineering projects that protect harbors, beaches, and coastal infrastructure from wave damage. As climate change accelerates the rate of sea level rise, Munk’s work on tides, ocean currents, and wave dynamics is more relevant than ever for California’s future.

Walter Munk’s contributions to oceanography stretched well beyond his wartime work and Project Mohole. He was instrumental in shaping how we understand everything from deep-sea currents to climate patterns, earning him numerous awards and accolades. His work at Scripps set the stage for the institution’s current status as a world leader in oceanographic research.

One of the most notable examples of this work was an experiment led by Munk to determine whether acoustics could be used to measure ocean temperatures on a global scale, offering insights into the effects of global warming. In 1991, Munk’s team transmitted low-frequency underwater acoustic signals from a remote site near Heard Island in the southern Indian Ocean. This location was strategically chosen because sound waves could travel along direct paths to listening stations in both the Pacific and Atlantic Oceans. The experiment proved successful, with signals detected as far away as Bermuda, New Zealand, and the U.S. West Coast. The time it took for the sound to travel was influenced by the temperature of the water, confirming the premise of the study.

Walter Munk in 2010 after winning the Crafoord Prize. (Crafoord Prize)

Munk passed away in 2019 at the age of 101, but his influence lives on. His approach to science—marked by curiosity, boldness, and a willingness to take on complex, high-risk projects—remains an inspiration for generations of scientists. He was a giant not only in oceanography but also in shaping California’s role in global scientific innovation. As the state faces the challenges of a changing climate, Munk’s legacy as the “Einstein of the Oceans” continues to be felt along its shores and beyond.

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John Isaacs, the Maverick Oceanographer Who Wanted to Tow Icebergs to California

An AI rendering of Isaacs’ bold idea (Midjourney)
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California’s water crises have always inspired bold solutions, but few ideas rival the sheer audacity of John Isaacs’ proposal to tow a giant Antarctic iceberg to San Diego. A brilliant and unconventional researcher at the Scripps Institution of Oceanography, Isaacs made waves in 1949 with his imaginative, though controversial, plans to quench California’s chronic droughts by harnessing the frozen reservoirs of the polar regions.

Isaacs’ career was defined by his boundary-pushing ideas. A polymath with a keen interest in marine biology, engineering, and climate science, he often operated at the intersections of disciplines, challenging conventional thinking. The iceberg-towing proposal exemplified his knack for blending vision and pragmatism—if one were willing to stretch the definition of “pragmatic.”

Isaacs theorized that large Antarctic icebergs could be wrapped in insulation to slow their melting and then towed by tugboats up the Pacific coast. The journey, spanning thousands of miles, would end with the iceberg positioned off the coast of Southern California, where its meltwater could be harvested to replenish reservoirs. Isaacs estimated that a single large iceberg, some the size of Manhattan, could supply tens of billions of gallons of freshwater—enough to offset drought conditions for millions of people.

John D. Isaacs (Scripps Institution of Oceanography)

The concept wasn’t a fleeting thought. Isaacs expanded on his idea in 1956, suggesting the capture of an eight-billion-ton iceberg—20 miles long, 3,000 feet wide, and 1,000 feet deep—and towing it to San Clemente Island off San Diego in approximately 200 days. He even calculated that a fleet of six ocean-going tugs could accomplish the feat, taking about six months to tow the iceberg from the 65th parallel south to the Californian coast.

In October 1973, the RAND Corporation took Isaacs’ vision further with an extensive report titled “Antarctic Icebergs as a Global Fresh Water Source” for the National Science Foundation. This 96-page document, authored by J.L. Hult and N.C. Ostrander, provided the most detailed scheme to date, transforming the theoretical idea into a more structured and mathematical model. It envisioned the creation of an “iceberg train” and delved into the technicalities and logistics of towing icebergs across the ocean. Hult explained, “Bringing icebergs to where the water is needed was suggested by John Isaacs of Scripps Institute of Oceanography in the 1950s. It is our job to show how practical it is.” However, the plan was not without eccentricities—such as the suggestion of using a floating nuclear power plant to supply the energy needed for the operation. The RAND report exemplified the ambition of its era, though many of its assumptions leaned heavily on theoretical modeling rather than practical viability.

AI rendering of an iceberg being dismantled (Midjourney)

Isaacs wasn’t alone in dreaming big. His proposal came at a time when other researchers and engineers were exploring similarly outlandish ideas, like seeding clouds with silver iodide to induce rain or building massive aqueducts from Alaska. But Isaacs’ iceberg scheme captured imaginations for its sheer romance and its symbolic uniting of Earth’s polar extremes with parched California landscapes.

Isaacs knew his plan faced enormous technical, logistical, and financial hurdles. For one, towing an iceberg would require immense energy and coordination, as well as a fleet of powerful ships. The iceberg’s tendency to melt during transit—especially when entering warmer waters—posed another significant obstacle. To mitigate this, Isaacs suggested covering the iceberg in reflective materials or insulating blankets to slow heat absorption.

Then there was the issue of economics. Calculations revealed that the cost of transporting a single iceberg could run into the billions, far outweighing the price of more conventional water solutions like desalination plants or water recycling programs. Critics also worried about ecological disruption, from changing ocean currents to the impact on marine ecosystems along the iceberg’s route.

While Isaacs’ iceberg idea was never realized, it sparked a wave of creative thinking about unconventional water solutions. Today, some of the principles behind his ideas have resurfaced in modern innovations. Advanced engineering methods, including climate-resilient infrastructure and adaptive water management, owe a debt to the exploratory spirit of Isaacs’ era.

AI rendering of an aqueduct built to carry water from Alaska to California (Midjourney)

The iceberg-towing concept is occasionally revisited, especially as climate change intensifies water scarcity. For example, in recent years, researchers in the United Arab Emirates have considered similar plans to bring freshwater from polar ice to arid regions. Advances in materials science and energy efficiency have made some aspects of Isaacs’ vision more feasible, though the logistics remain daunting.

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John Isaacs’ career extended far beyond icebergs. He contributed to deep-sea exploration, studied the effects of nuclear fallout on marine life, and was an early advocate for understanding the ocean’s role in climate systems. His interdisciplinary approach and willingness to embrace unorthodox solutions left a lasting impact on oceanography and environmental science.

Isaacs’ iceberg proposal remains a testament to his fearless creativity and his deep commitment to solving humanity’s greatest challenges. While the world never saw an iceberg floating past Los Angeles, Isaacs’ bold thinking continues to inspire researchers grappling with the complex interplay of science, technology, and the environment.

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