How a Tiny Beetle Helped Save California

California’s citrus industry confronted a deadly challenge, leading to a groundbreaking innovation in pest control.

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In the sun-drenched orchards of late 19th-century California, a crisis was unfolding that threatened to decimate the state’s burgeoning citrus industry. The culprit was a small sap-sucking insect native to Australia called the cottony cushion scale (Icerya purchasi). First identified in New Zealand in 1878, this pest had made its way to California by the early 1880s, wreaking havoc on citrus groves. The pest is believed to have arrived in the United States through the global trade of plants, a common vector for invasive species during the 19th century. As horticulture expanded globally, ornamental plants and crops were frequently shipped between countries without the quarantine measures we have today. Once established in the mild climate of California, the cottony cushion scale found ideal conditions to thrive, spreading rapidly and wreaking havoc on the citrus industry.

The cottony cushion scale infested trees with a vengeance, covering branches and leaves with a white, cotton-like secretion. This not only weakened the trees by extracting vital sap but also led to the growth of sooty mold on the honeydew excreted by the insects, further impairing photosynthesis. Growers employed various methods to combat the infestation, including washing trees with whale oil, applying blistering steam, and even detonating gunpowder in the orchards. Despite these efforts, the pest continued its relentless spread, causing citrus exports to plummet from 2,000 boxcars in 1887 to just 400 the following year. This decline translated to millions of dollars in lost revenue, threatening the livelihoods of countless farmers and jeopardizing the state’s citrus economy, which was valued at over $10 million annually (approx. $627 million in today’s dollars) during this period.

Orange and lemon groves, along with the home of citrus pioneer William Wolfskill, circa 1882. (California Historical Society)

In 1885, the independent growers across Southern California banded together in response to the insect invasion and the broader difficulties facing citrus growers at the time, forming the state’s first fruit cooperative, which would later become Sunkist. Despite their efforts, homemade mixtures of kerosene, acids, and other chemicals failed to halt the relentless spread of Icerya purchasi. The pests, with an endless supply of citrus trees to feed on, continued to multiply unchecked. New laws mandated growers to uproot and burn infected orange trees, but the devastation was widespread. By 1888, real estate values, which had soared by 600 percent since 1877, had plummeted.

Enter Charles Valentine Riley, the Chief Entomologist for the U.S. Department of Agriculture. A visionary in the field of entomology, Riley had previously attempted biological control by introducing predatory mites to combat grape phylloxera in France, albeit with limited success. Undeterred, he proposed a similar strategy for the cottony cushion scale crisis. In 1888, Riley dispatched his trusted colleague, a fellow entomologist named Albert Koebele, to Australia to identify natural enemies of the pest.

The cottony cushion scale infestations were so severe that citrus trees appeared as though they had been coated with artificial snow, resembling Christmas flocking. Fruit production sharply declined, and many trees succumbed to the damage. (UC Riverside)

Interestingly, Valentine resorted to subterfuge to send an entomologist to Australia despite Congress’s objections. Lawmakers had prohibited foreign travel by the Agriculture Department to curb Riley’s frequent European excursions. However, Riley, well-versed in navigating political obstacles, cleverly arranged for an entomologist to join a State Department delegation heading to an international exposition in Melbourne.

Koebele’s expedition proved fruitful. He worked with Australian experts to locate the pest in its rare habitats along with its natural enemies, including a parasitic fly and approximately the Vedalia beetle. The vedalia beetle (Rodolia cardinalis) is a small ladybird with a voracious appetite for the cottony cushion scale. Koebele collected and shipped hundreds of these beetles back to California. Upon their release into infested orchards, the vedalia beetles rapidly established themselves, feasting on the scales and reproducing prolifically. Within months, the cottony cushion scale populations had diminished dramatically, and by 1890, the pest was largely under control across the state. This 1888-89 campaign marked the beginning of biological control in the United States, a strategy involving the introduction of natural predators to manage invasive pests.

In her 1962 classic Silent Spring, Rachel Carson described the Novius beetle’s work in California as “the world’s most famous and successful experiment in biological control.”

Novius ladybug devours an Icerya. (UC Riverside)

This was far from the last time California employed such measures. It became a relatively common practice to introduce new species to control those that posed threats to the state’s economically vital crops, but not always successfully.

In the 1940s, California introduced parasitic wasps such as Trioxys pallidus to control the walnut aphid, a pest threatening the state’s walnut orchards. These tiny wasps laid their eggs inside the aphids, killing them and dramatically reducing infestations, saving the industry millions of dollars. Decades later, in the 1990s, the state faced an invasive glassy-winged sharpshooter, a pest that spread Pierce’s disease in grapevines. (Interesting fact: The glassy-winged sharpshooter drinks huge amounts of water and thus pees frequently, expelling as much as 300 times its own body weight in urine every day.) To combat this, scientists introduced Gonatocerus ashmeadi, a parasitic wasp that targets the pest’s eggs. This biological control effort helped protect California’s wine industry from devastating losses.

The Vedalia beetle (novius cardinalis) also known as the cardinal ladybird (Katja Schulz Wikipedia)

While the introduction of the vedalia beetle was highly effective and hailed as a groundbreaking success, biological control efforts are not without risks, often falling prey to the law of unintended consequences. Although no major ecological disruptions were recorded in the case of the cottony cushion scale, similar projects have shown how introducing foreign species can sometimes lead to unforeseen negative impacts. For example, the cane toad in Australia, introduced to combat beetles in sugarcane fields, became a notorious ecological disaster as it spread uncontrollably, preying on native species and disrupting ecosystems. Similarly, the mongoose introduced to control rats in sugarcane fields in Hawaii also turned predatory toward native birds. These examples highlight the need for meticulous study and monitoring when implementing biological control strategies. Today, regulatory frameworks require rigorous ecological assessments to minimize such risks.

The glassy-winged sharpshooter (Georgia Tech)

In the case of the Vedalia beetle, its precise and targeted predation led to a highly successful outcome in California. Citrus quickly became one of the state’s most dominant and profitable crops, helping to establish California as a leader in agricultural production—a position it continues to hold firmly today.

This groundbreaking use of biological control not only rescued California’s citrus industry but also established a global precedent for environmentally sustainable pest management. The success of the Vedalia beetle’s introduction showcased the power of natural predators in managing agricultural pests, offering an alternative to chemical pesticides. While pesticides remain widely used in California and across the world, this effort underscores the value of understanding ecological relationships, evolutionary biology, and the benefits of international scientific collaboration.

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The story of the Vedalia beetle and the cottony cushion scale highlights human ingenuity and the effectiveness of nature’s own checks and balances. It stands as an early example of integrated pest management, a method that continues to grow and adapt to meet modern agricultural challenges. This successful intervention underscores the importance of sustainable practices in protecting both our food systems and the environment.

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

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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.

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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All the Fish We Did Not See – The Discovery of the Ocean’s False Bottom off California

A paper nautilus or Argonaut, a group of pelagic octopuses that dwell in the ocean’s twilight zone. (Erik Olsen)

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In the summer of 1942, aboard the USS Jasper, a team of scientists embarked on a mission off the coast of San Diego, California, a hub for U.S. Navy operations and other military activities vital for the Pacific Theater of World War II. Their goal was to test a new technology called “long-range active sonar,” developed to detect enemy submarines—specifically Japanese submarines and German U-boats—during World War II. Long-range active sonar is a technology that sends sound waves through the ocean to map and visualize the seafloor across great distances, revealing details of underwater topography and structures that would otherwise remain hidden beneath the waves.

The expedition was led by Carl F. Eyring, an accomplished acoustic physicist known for his pioneering work in sonar technology. Eyring, along with his colleagues Ralph A. Christensen and Russell W. Raitt, played crucial roles in the mission. Their combined expertise in acoustics, naval operations, and marine science made them the perfect team to explore the deep ocean with sound.

The USS *Jasper* in 1945—just a few years after scientists discovered the first evidence of the Deep Scattering Layer during a research cruise aboard the ship. (Photo: Naval History and Heritage Command)

As they deployed sonar pulses into the depths, they encountered an unexpected anomaly: a persistent, dense layer approximately 300 yards (about 274 meters) below the surface that scattered their acoustic signals. It was almost as if the ocean floor had risen, looming closer with a strange, unyielding presence that defied all explanations.

This new reading was a complete anomaly, contradicting everything they knew about the seafloor’s topology. It was as though a solid mass had somehow materialized in the depths—a mass dense enough to obscure their sonar and make the familiar landscape unrecognizable. At the same time, their signal strength readings spiked erratically, suggesting significant interference in the water.

Carl F. Eyring (Brigham Young University)

The discovery of this peculiar layer presented an intriguing puzzle to the scientists aboard the Jasper. Yet, with a war raging, they couldn’t afford to lose focus. Instead, they concentrated on measuring its dimensions and mitigating the acoustic interference it created. Determining its true nature would have to wait for another time.

It wasn’t until almost three years later, in 1945, that oceanographer Martin Johnson deployed nets into the Pacific and uncovered the truth: the layer was actually a massive cloud of marine animals, most no larger than a human finger, migrating daily from the deep ocean to the surface and back. This dense biological layer, packed with animals capable of reflecting sonar, had created the illusion of a solid mass, effectively “masking” the true depth of the ocean floor by reflecting sonar waves off the swim bladders of the fish and other marine organisms.

Bristlemouth trawled from the ocean’s twilight zone (Erik Olsen)

This phenomenon, later termed the Deep Scattering Layer (DSL), created a “false bottom” in sonar readings, revealing an unexpectedly dense concentration of biological life in a mid-ocean zone once thought to be relatively sparse. The discovery of the DSL challenged assumptions about life distribution in the ocean, showing that vast numbers of organisms—such as fish, squid, and zooplankton—populate these depths, rising and descending with daily cycles to avoid predators and optimize feeding.

The DSL is situated within the ocean’s mesopelagic zone, commonly referred to as the twilight zone, which extends from about 200 to 1,000 meters below the surface. This region is characterized by minimal sunlight penetration and hosts a diverse array of marine life. Indeed, this huge swath of biomass is exactly what the sonar was picking up. This remarkable behavior observed in this zone is the diurnal vertical migration—the largest daily movement of biomass on Earth, the world’s largest animal migration. Each evening, billions of organisms (some scientists actually believe they number into the quadrillions) including small fish like lanternfish, hatchetfish and bristlemouths, ascend toward the surface to feed under the cover of darkness, retreating to the depths at dawn to evade predators. (Bristlemouths, by the way, are said to be the most numerous vertebrate on the planet.)

Scattering layer seen on sonar (Erik Olsen)

The discovery of the DSL provided significant insights into marine biology and oceanography. The layer’s composition—primarily swarms of marine animals with gas-filled swim bladders—explained the sonar reflections that mimicked the seafloor. This understanding highlighted the abundance and biodiversity of life in the twilight zone and underscored the importance of these organisms in oceanic ecosystems.

The discovery also led over time to an understanding of the role this layer plays in the carbon cycle, the very phenomenon that helps regulate Earth’s climate. The daily migration of marine animals in this layer is not just a remarkable biological spectacle; it is also a key mechanism for transporting carbon from the ocean’s surface to its depths. As these organisms ascend at night to feed and then return to deeper waters during the day, they excrete waste and many of them die, effectively moving carbon downwards, often sequestering it in the deep ocean floor where it can remain for centuries. This process, known as the biological carbon pump, plays a vital role in mitigating the effects of carbon dioxide in the atmosphere, thus contributing to climate stability. Without the existence of the Deep Scattering Layer and its role in the carbon cycle, the Earth’s carbon balance would be significantly different, highlighting just how interconnected marine ecosystems are with global climate regulation.

In the decades following its discovery, the DSL has remained a subject of scientific inquiry. Advancements in sonar technology and deep-sea exploration have revealed the layer’s dynamic nature and its role in global carbon cycling.

Current research into the twilight zone, particularly by scientists at the Woods Hole Oceanographic Institution (WHOI), is uncovering fascinating insights into this enigmatic region of the ocean. The twilight zone remains one of the least explored parts of the ocean, despite being home to an abundance of life and playing a crucial role in global biogeochemical cycles. Woods Hole has been at the forefront of investigating this layer, employing advanced technology like remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), submersibles, and cutting-edge acoustic techniques to understand its complex dynamics and ecosystem.

One of the leading researchers at WHOI, Dr. Heidi Sosik, has been focusing on the role that the twilight zone plays in the carbon cycle. Sosik’s work involves the use of automated imaging technologies to analyze the behavior and diversity of the organisms inhabiting this region. By documenting their daily migrations and interactions, Sosik’s team has been able to quantify the extent to which these animals contribute to carbon transport. This research is essential for understanding how much carbon is effectively being sequestered from the atmosphere through these daily migrations.

Another prominent scientist at WHOI, Dr. Andone Lavery, is working to map the twilight zone’s acoustics in unprecedented detail. Lavery’s expertise in underwater sound technology has helped reveal not only the composition of the Deep Scattering Layer but also the behaviors of its inhabitants. Lavery’s recent findings indicate that the twilight zone’s acoustic properties are far more dynamic than previously thought, and these properties can significantly affect how marine animals detect predators and prey, as well as how researchers measure biomass in this layer.

Dr. Simon Thorrold, also from WHOI, has been studying the food web dynamics within the twilight zone. Thorrold’s research has uncovered surprising insights into predator-prey relationships among mesopelagic species. Using chemical tracers, his team has been able to track the movement of nutrients through the food web, revealing that many animals from the twilight zone are integral to surface ecosystems as well, either through vertical migration or being preyed upon by larger species such as tuna, swordfish, and marine mammals.

Scientists use a Triton submersible to explore the ocean’s twilight zone in the Bahamas. (Erik Olsen)

In addition, WHOI has been collaborating with international partners on the “Twilight Zone Exploration” (TZX) project, which aims to better understand how human activities, such as fishing and climate change, are impacting this critical part of the ocean. The mesopelagic zone is increasingly targeted by commercial fishing due to the sheer biomass it holds. Dr. Sosik and her colleagues are actively studying the potential consequences of harvesting these species, considering their importance in carbon sequestration and as a key link in marine food webs.

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Together, these efforts are gradually revealing the twilight zone’s secrets, emphasizing its importance not only in regulating climate but also in maintaining the health of marine ecosystems. As the pressures of climate change and human exploitation continue to grow, understanding this mysterious part of the ocean has never been more critical.

The USS Jasper‘s encounter with the false bottom off California’s coast stands as a pivotal moment in oceanographic history. It not only unveiled the hidden complexities of the ocean’s twilight zone but also bridged the gap between military technology and marine science, leading to a deeper appreciation of the intricate and interconnected nature of Earth’s marine environments.

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Cadillac Desert: How Marc Reisner Changed the Way We See Water

Los Angeles Aqueduct passing through Palmdale, California (Photo: Erik Olsen)

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Marc Reisner’s Cadillac Desert: The American West and Its Disappearing Water remains a towering achievement in environmental journalism, decades after its publication in 1986. Chronicling the history, politics, and ecological consequences of water management in the American West, Cadillac Desert is not just an exposé of the past—it’s a cautionary tale that resonates today. With precision and passion, Reisner unraveled the intricacies of an arid region’s improbable transformation into one of the world’s most agriculturally productive and densely populated areas. His work has had a profound and lasting impact on how we understand water politics and environmental sustainability in California and beyond.

Cadillac Desert stands as a fitting successor to Wallace Stegner’s Beyond the Hundredth Meridian, continuing the exploration of water’s defining role in the American West. While Stegner championed the visionary work of John Wesley Powell and exposed the folly of ignoring the region’s arid realities, Reisner picked up the torch decades later to chronicle how those warnings were systematically ignored. Where Stegner painted a historical narrative of ambition and hubris, Reisner delivered a scathing and urgent critique of water politics, detailing the environmental and economic consequences of massive dam-building projects and unsustainable resource exploitation.

Cadillac Desert is, at its core, a gripping investigation into the manipulation of water resources in the American West. Reisner meticulously details how the construction of massive dams, reservoirs, and aqueducts enabled the transformation of a naturally dry landscape into a gargantuan economic powerhouse. From the Colorado River to the Los Angeles Aqueduct to California’s Central Valley, Cadillac Desert paints a vivid picture of engineering triumphs and environmental sacrifices, revealing the cost of this development to natural ecosystems, Indigenous communities, and future generations.

One of Reisner’s central stories is the tale of the Owens Valley. In the early 20th century, this fertile agricultural region was drained dry when the Los Angeles Aqueduct diverted its water to fuel the growing metropolis of Los Angeles. The story, replete with backroom deals, broken promises, and outraged locals, serves as a symbol of the greed and ambition that defined water politics in the West. Reisner weaves this narrative with the larger saga of William Mulholland, the ambitious engineer whose name is synonymous with both the success and hubris of L.A.’s water empire. This saga of water, power, and betrayal would later inspire the dark and iconic tale of Chinatown, the Roman Polanski film that captured the moral ambiguities and human cost of Los Angeles’ relentless thirst for growth.

Marc Reisner (Water Education Foundation)

Another cornerstone of the book is the story of the Colorado River, a waterway Reisner calls the most controlled and litigated river on Earth. He charts the creation of the Hoover Dam and the vast network of canals and reservoirs that distribute its water across seven states. The book reveals how over-allocation of the river’s resources, coupled with decades of drought, have pushed it to the brink of collapse—an issue that has only grown more urgent since Cadillac Desert was published.

Hoover Dam in 1936 (United States Bureau of Reclamation)

Reisner also dissects the Central Valley Project and the State Water Project, two gargantuan efforts to turn California into an agricultural Eden. By moving water from Northern California to the arid south, these projects enabled California’s emergence as a global agricultural leader. But Reisner doesn’t shy away from exposing the social and environmental consequences: drained wetlands, salt buildup in soils, and a system that prioritizes agribusiness over the needs of small farmers and urban residents.

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What makes Cadillac Desert extraordinary is not just its scope but its style. Reisner’s journalistic rigor is matched by his ability to tell a compelling story. He brings characters like Mulholland and Floyd Dominy, the brash commissioner of the U.S. Bureau of Reclamation (part of the U.S. Department of the Interior), to life with vivid detail. At the same time, his writing is infused with moral urgency, challenging readers to question the sustainability of a society built on unsustainable water use.

Owens River in the Eastern Sierra (Erik Olsen)

The book’s legacy is immense. It galvanized environmentalists and policymakers, inspiring debates about water rights, conservation, and the future of development in the West. Documentaries, academic studies, and even contemporary water management policies owe much to the awareness Cadillac Desert raised. In California, where water battles continue to define politics and development, the book remains as relevant as ever.

As we face a future of intensifying droughts and climate change, Reisner’s insights grow more prescient by the day. California is still grappling with the overuse of groundwater, the challenges of aging infrastructure, and the inequities in water distribution. And while new technologies and policies offer hope, the central question Cadillac Desert poses—how do we balance human ambition with the limits of nature?—remains unanswered.

Tragically, Reisner passed away in 2000 at the age of 51 from cancer, cutting short the life of a writer who had so much more to contribute to our understanding of environmental challenges. His death was a significant loss to the fields of journalism and environmental advocacy, but his legacy endures through his groundbreaking work. Cadillac Desert continues to inspire new generations to confront the urgent questions surrounding water use, conservation, and the future of the planet.

Marc Reisner’s Cadillac Desert is not just a history of water in the West; it is a call to rethink our relationship with one of the planet’s most precious resources. At once an epic tale and an urgent warning, it stands as a monumental testament to the price we pay for bending nature to our will.

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Unearthing the Secrets of the Sierra Nevada Batholith

An example of Sierra Nevada batholith. There are several domes in Yosemite besides Half Dome. (Erik Olsen)

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Ansel Adams, with his iconic black-and-white photographs of Yosemite and the Sierra Nevada, likely never realized that his lens was capturing not just breathtaking landscapes but one of geology’s most fascinating phenomena—the Sierra Batholith, a colossal formation of granite that lies at the heart of the mountains he immortalized. The Sierra Batholith is a massive granite body that reveals the tale of ancient volcanic activity in California, showcasing nature and time as master artists, and the slow tectonic forces that have shaped the Earth’s crust over millions of years.

Discussing the Sierra batholith, the writer John McPhee wrote: “It lies inside the Sierra like a big zeppelin. Geologists in their field boots mapping outcrops may not have been able to find a bottom, but geophysicists can, or think they can, and they say it is six miles down. If so, the batholith weighs a quadrillion tons, and its volume is at least a hundred and fifty thousand cubic miles.”

The Sierra Batholith is unique because it represents a massive, exposed section of the Earth’s continental crust formed deep underground during the Mesozoic era, between 85 and 220 million years ago. Unlike typical mountain ranges that form through surface processes, the Sierra Batholith was created as molten rock, or magma, cooled and solidified far beneath the Earth’s surface.

A batholith is a gargantuan underground rock formation made up mostly of intrusive igneous rock, predominantly granite.” Intrusive” in this context doesn’t mean the rock is barging into conversations—it refers to rock that formed beneath the Earth’s surface as molten magma slowly cooled and solidified. The Sierra Nevada batholith is a titan among batholiths, covering an area of about 40,000 square kilometers (16,000 sq. miles).

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How did this underground monolith come into being? Picture the Earth’s crust as a sort of geological lasagna, consisting of multiple layers of rock. When the Pacific Plate and the North American Plate crashed into one another—intense pressure and heat accumulated deep within the Earth. The result is the formation of magma, which then cooled and solidified slowly below the Earth’s crust. The slow cooling allowed minerals to crystallize, creating a texture in the rock that’s coarse and beautifully patterned—not unlike granite countertops for your kitchen, but on a monumental scale.

The Sierra Nevada Batholith was only revealed after vertical miles of Earth’s crust above it eroded away. Stretching from just north of Lake Tahoe to Tehachapi Pass, this massive formation resembles an air mattress—450 miles long, 60 miles wide, and about eight to nine miles thick, with six miles still buried underground and two to three miles towering above the surrounding landscape. The sheer size, scale, and immense mass are awe-inspiring—and it’s all right here in California.

This creation process was far from uniform—the batholith is actually not a single mass, per se, but a cluster of blobs of molten rock fused at the edges. These blobs, called plutons, are clustered together like cobblestones in a street or the uneven domes of a bubble wrap sheet. What we now see are the rounded tops of about 20 oval-shaped plutons, each around 10 by 20 miles in size. Chemically, each blob varies slightly. Granite, made mostly of silica, which forms 60 to 80 percent of its mass, gets its whitish hue from silica, with black flecks of feldspar and hornblende, sometimes tinged with reddish iron oxide. The slower the cooling, the more time quartz crystals had to form.

One of the largest and youngest plutons in the Sierra is called the Whitney Intrusive Suite, and it is the foundation of the nation’s tallest peak outside of Alaska, Mt. Whitney.

A geologic map of Yosemite National Park showing the many intrusions that make up this part of the Sierra Nevada Batholith.

Natural forces like wind, water, and glaciers have gradually eroded the Earth’s surface, exposing the underlying granite. Imagine the work of an infinitely patient sculptor, slowly chipping away at a block of marble year after year, century after century. Except here, the sculptor is Mother Nature, and the time frame is geological, spanning epochs rather than mere decades or centuries.

One fascinating facet of this story is how glaciers have been among the most dramatic artists in nature’s magnificent art gallery. Their slow, relentless movement sculpted features like Yosemite Valley, one of the most breathtaking landscapes on Earth.

Half Dome in Yosemite, a granite giant of the Sierra Batholith, showcases millions of years of cooling magma and erosion. (Erik Olsen)

But the Sierra Nevada batholith isn’t just a stationary slab of rock—it’s also a dynamic part of California’s ecosystem. The granite affects the way water moves or stagnates in the region, influencing local hydrology and, by extension, water supply. When the snow in the Sierra Nevada mountains melts, it feeds rivers and lakes, many of which are essential to California’s agricultural and urban areas. Imagine the batholith as a silent but vital cog in the wheel of California’s complex water system.

One excellent resource to learn more about the Sierra and the Sierra batholith is Kim Stanley Robinson‘s The High Sierra: A Love Story. The book is an evocative blend of memoir, natural history, and environmental meditation, centered around the Sierra Nevada mountains, a region Robinson has deeply cherished for decades. Robinson, widely regarded as one of today’s greatest science fiction writers, has authored numerous books on topics ranging from space exploration to climate change. Yet one of his deepest passions is hiking in the Sierra.

Half Dome, carved from the granite of the Sierra Batholith, offers a glimpse into Earth’s deep history, where ancient magma chambers solidified beneath the surface and were gradually revealed through uplift and erosion. (Erik Olsen)

In the book, he explores the geologic grandeur, ecological richness, and personal significance of this mountain range, offering readers a vivid portrayal of its granite peaks, alpine meadows, and glacial valleys. Robinson intertwines his own hiking experiences with reflections on the Sierra’s geological formation, the indigenous histories of the land, and the environmental challenges it faces today. His narrative is as much an ode to the beauty and solitude of the Sierra as it is a call for greater environmental stewardship, showcasing his talent for combining science with a profound emotional connection to the natural world. (If you haven’t yet read one of his books, you should. Start with Red Mars.)

Sierra Nevada from Lone Pine (Erik Olsen)

If you’re the adventurous type with a penchant for rock climbing or hiking, the Sierra Nevada batholith serves as both your playground and your classroom. Whether you’re scaling the granite walls of El Capitan or hiking the trails near Lake Tahoe, you’re traversing a landscape that’s millions of years old. Each crevice, each outcrop, and each boulder tells a tale of geological drama spanning eons.

Looking back at John McPhee’s Assembling California: A Journey through Geology and Time

Sierra Nevada Mountains and Hot Creek Geological Site (Erik Olsen)

California’s diverse landscapes, rich history, and abundant natural phenomena have inspired many scientific-themed popular books, ranging from John Steinbeck’s “The Log from the Sea of Cortez,” with its focus on marine biology, to Mary Austin’s “The Land of Little Rain,” a lyrical examination of California’s desert environment, not to mention the late Marc Reisner’s Cadillac Desert, an epic history of California’s contentious relationship with water. (I’ve read it twice.)

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But when it comes to exploring the state’s geology – its mountains, coastlines, and, most notably, its fault lines – few books can match the prowess and eloquence of John McPhee’s “Assembling California“. Part of his Pulitzer-winning series, “Annals of the Former World,” the book offers a comprehensive and accessible tour through the geological history of California, crafting a fascinating narrative that is as engaging as it is informative.

John McPhee is an acclaimed American writer and pioneer of creative nonfiction, renowned for his deeply researched and beautifully crafted works that often explore topics related to nature, science, and geography. A long-time staff writer for The New Yorker and the author of over 30 books, McPhee is celebrated for his ability to turn seemingly ordinary subjects—such as geology, oranges, or transportation—into compelling narratives. His distinctive style blends meticulous research with accessible, often poetic prose that has been widely immitated. I’ve read several of McPhee’s books and while some of the work can be hard going, I’m usually very satisfied once I’m done. Assembling California is, in my opinion, one of his best.

Here’s an excerpt:

An old VW bus is best off climbing the Sierra from the west. Often likened to a raised trapdoor, the Sierra has a long and planar western slope and—near the state line—a plunging escarpment facing east. The shape of the Sierra is also like an airfoil, or a woodshed, with its long sloping back and its sheer front. The nineteenth-century geologist Clarence King compared it to “a sea-wave”—a crested ocean roller about to break upon Nevada. The image of the trapdoor best serves the tectonics. Hinged somewhere beneath the Great Valley, and sharply faulted on its eastern face, the range began to rise only a very short geologic time ago—perhaps three million years, or four million years—and it is still rising, still active, continually at play with the Richter scale and occasionally driven by great earthquakes (Owens Valley, 1872). In geologic ages just before the uplift, volcanic andesite flows spread themselves over the terrain like butterscotch syrup over ice cream. Successive andesite flows filled in local landscapes and hardened flat upon them. As the trapdoor rises—as this immense crustal block, the Sierra Nevada, tilts upward—the andesite flows tilt with it, and to see them now in the roadcuts of the interstate is to see the angle of the uplift.
John McPhee in Assembling California

The Sierra Nevada, a massive mountain range stretching like a spine nearly the length of California, provides the central geological narrative in “Assembling California”. Known for its stark beauty and dramatic peaks, the Sierras are also a textbook example of the immense forces that shape our planet. (We’ve written and will continue to write about them.) McPhee masterfully explicates how tectonic activity shaped this terrain over millions of years, giving readers a sense of the awe-inspiring age and dynamism of the Earth.

A brief bit about the man: Born in 1931, McPhee studied at Princeton University and Cambridge, and his writing straddles diverse topics from basketball to nuclear energy. His primary strength lies in his ability to seamlessly interweave complex scientific principles with engrossing human stories (there’s always an interesting character and the heart of his work), making the intricate world of science both comprehensible and enjoyable to the lay reader. His skill and prolificacy have earned him numerous accolades, including the Pulitzer Prize.

Assembling California stands out for its illuminating journey through California’s intricate geological history. Traveling with the late geologist Eldridge Moores of the University of California Davis, McPhee unpacks the layered story of California’s geology from its seismic activity to its unique rock formations. There is an excellent excerpt in a 1992 issue of the New Yorker.

Moores was a renowned geologist known for his significant contributions to understanding the geological history and structure of the Earth, particularly in relation to plate tectonics. Born in 1938 in Phoenix, Arizona, he spent the bulk of his career as a professor of geology at Davis, where his research significantly advanced the theory of plate tectonics. He was particularly interested in the geology of his adopted home state, California. Moores also held the position of President of the Geological Society of America in 1996. Apart from his boundless energy, Moores’ real gift was his vision: his ability to “see” geologic history in a pile of rocks. His passionate teaching style and profound knowledge made him a beloved figure in the field of geology. Moores died in a tragic accident in 2018 while on a field trip in Greece, leaving a significant void in the geology world.

Moores explains to McPhee how the Sierra Nevada range didn’t just emerge from the Earth’s crust, as geologists long thought. Instead, the building blocks bubbled up from faraway rifts in the ocean floor called “spreading centers,” then transported thousands of miles on moving plates and piled up onto the North American continent.

Sierra Nevada Mountains and Owens River (Erik Olsen)

The movement of the Earth’s crust along fault lines, as in the well-known San Andreas Fault, is a central theme of the book. By explaining the shifting of tectonic plates, McPhee brings to life the reality of living in California: a landscape that is constantly, if imperceptibly, in motion. His descriptions of earthquakes, both historic and potential future ones, vividly underscore the seismic hazards associated with residing in the state. McPhee’s ability to humanize these impersonal geologic processes is a testament to his storytelling prowess. You will learn a lot about what happens to the California beneath your feet.

However, “Assembling California” is not just a tale of geological forces. McPhee also weaves in fascinating narratives about gold prospectors and vineyard owners, infusing the state’s human history into its ancient geological story. You really can’t tell the story of modern California without delving into the resource-driven economic narratives that are a fundamental part of the state’s history. We try to do a lot of that in this magazine.

For those who want to go beyond McPhee, another fine author is Simon Winchester, whose “Crack at the End of the World” picks up where McPhee left off, both in terms of theme and approach. Winchester, a British author and journalist known for his popular science writing, explores the devastating 1906 San Francisco earthquake. Like McPhee, Winchester expertly merges detailed geological explanations with human stories, providing a compelling account of one of the most significant natural disasters in American history. This is also a very fine book.

The legacy of “Assembling California” lies not just in its rich storytelling but also in the path it blazed for a new kind of popular science writing – one that’s engaging, comprehensive, and profoundly human. By understanding our planet’s past and the forces that shape it, we are better prepared to navigate its future. As readers, we owe a debt of gratitude to writers like McPhee and Winchester who, through their craft, help us appreciate the intricate dance between the Earth’s geological processes and human civilization.

Since McPhee wrote “Assembling California,” technology has made leaps and bounds in the field of geology. Advancements in technology like LIDAR (Light Detection and Ranging), which uses lasers to measure distances and can create high-resolution maps of the Earth’s surface, and improvements in seismograph technology and satellite imaging, have allowed scientists to study geological phenomena in greater detail and with better accuracy.

Geology, like all scientific disciplines, evolves over time as new techniques and technologies become available. This progress often refines our understanding of geological phenomena and can lead to new theories and models. We’re still learning a lot about how our state literally came together, with new research being done all the time that sheds light on our mountains, coasts and valleys.

More recent studies of the San Andreas Fault, for instance, have allowed us to better understand the fault’s behavior, including how frequently significant earthquakes occur and what triggers them. For example a 2022 study from Lamont-Doherty Earth Observatory suggests that the San Andreas Fault moves slowly in a process called “creep,” which was previously thought to release tectonic stress and reduce earthquake risk. However, this new research suggests that this creeping segment might instead be accumulating stress, potentially leading to larger and more destructive earthquakes than previously anticipated.

Not exactly good news, but it’s always better to know what’s happening and to have science that backs it up, and McvPhee was a master at helping us understand he way the world works.

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