Imagine a bird that’s not only a reliable fixture on both coastal and inland landscapes, but also a winged hero with a knack for saving ecosystems and crops alike. Meet the California gull, a seemingly unassuming creature that’s the avian equivalent of a Toyota Camry: dependable, middle-of-the-road, and surprisingly full of stories. Far from just another seabird scrounging for scraps, this versatile gull is a fascinating study in adaptability, ecological impact, and even historical significance.
Birdwatching might be dismissed as a pedestrian hobby, but when you dive into the details, it’s a riveting blend of science, art, and natural history. Take the task of identifying a gull, for instance. You might think all gulls are created equal, but you’d be sorely mistaken. From the curvature of the bill to the tint of the feathers, each species presents its own unique set of traits. And in this realm, the California gull is the embodiment of middle-of-the-road reliability..
The California gull’s bill is a case study in avian averageness: not too long, not too short, but just right. Then there’s the back—a shade of gray that’s neither too dark nor too light. Size-wise, it’s comfortably nestled between the imposing giants and the pint-sized runts of the gull family. Even its legs are a kind of Goldilocks yellow—nothing too flashy or understated. The same goes for its migration pattern. This bird isn’t setting any long-distance records like the ambitious Arctic terns, nor is it stubbornly clinging to a single geographical point year-round. It moves around a reasonable amount—perhaps 500 to 1,000 miles—but always makes it back to familiar territory in good time.
California gull. (Larus californicus) Image: Wikipedia
And where might you spot this paragon of mediocrity? Well, in winter, they’re pretty much where you’d expect any self-respecting gull to be: on beaches, in harbors, hanging around landfills, playgrounds, and fields, or perhaps looking for morsels in tide pools and kelp beds. Come early summer, many venture inland to breed, but they generally make it back to their stomping grounds before the first school bell rings in September.
Yet for a bird that’s so unassuming, the California gull enjoys a surprising level of fame. Case in point: it’s the state bird of Utah, not California. That honor was bestowed upon it for its historical role during the initial Mormon settlement. The Sea Gull Monument in Salt Lake City honors the gull, who saved the people of Utah by consuming the Rocky Mountain crickets which were destroying all the crops in 1848. Quote from monument:
“The Mormon pioneers planted crops in the spring of 1848, after suffering great hunger during their first winter in the Salt Lake Valley. As the crops ripened, hordes of devouring crickets descended upon them from the foothills east of the valley. The Saints fought them with clubs, fire, and water. As they despaired of saving the next winter’s food, their prayers for deliverance from almost sure starvation were answered when thousands of sea gulls came to feed on the crickets. The Sea Gull Monument commemorates this modern-day miracle. The sea gull is now the Utah State bird.”
Moreover, the California gull has been an ecological hero in other ways. At Mono Lake in the Eastern Sierras of California, the gull has had a significant impact on bringing the lake back to life. (The lake is also known for its microbial aliens.) In the early part of the 20th century, Los Angeles’ voracious appetite for water led to shady deals by William Mulholland to secure access to Owens Lake. Declining water levels at Mono Lake threatened the gull population that nested there. But a decisive legal victory by the Save the Mono Lake Committee has ensured the lake is now maintained at healthier water levels, benefiting not just gulls but the entire ecosystem.
Mono Lake Photo: Erik Olsen
However, it’s not all sunny skies for this winged wonder. In the salt pans of South San Francisco Bay, the number of nesting California gulls has exploded—from a mere 24 nests in 1980 to a staggering 45,000 today. It’s a population boom that’s become a double-edged sword. With so many beaks to feed, the California gulls have taken to dining on their neighbors, including baby terns. This poses an ethical conundrum: when is it time to intervene and cull one species to protect another? A tough question—it’s a slippery slope that could eventually loop back to us humans, as we ponder our role in this intricately balanced web of life.
Off the coast of Monterey, California, researchers captured rare footage of one of the deep sea’s strangest residents: the Barreleye fish. With a see-through head and upward-facing, tube-shaped eyes, it looks like something dreamt up for a sci-fi film. Officially called Macropinna microstoma, this bizarre little fish is a real reminder of how much mystery still lies beneath the surface of the ocean and how otherworldly life can get down there.
First described in 1939, the fish astonished scientists who were stunned by its unique optical anatomy. The barreleye is found in the Pacific Ocean, with sightings ranging from the coasts of California, particularly around Monterey Canyon, to the mid-Pacific near Hawaii. Most commonly, it resides between 400 to 2,500 feet below the surface, a region known as the mesopelagic or “twilight” zone. At these depths, little light penetrates, making the area a seemingly inhospitable place for most life forms. But the Barreleye fish thrives here, adapting to its surroundings in the most bizarre ways.
Its most distinctive features, and the ones that give it its name, are its transparent head and barrel-shaped eyes that are usually directed upwards. These eyes are extremely sensitive to light, which is a scarce commodity where it lives. Interestingly, the eyes are encased in a dome-shaped, transparent head. This clear cranium allows the fish to capture as much light as possible, increasing its visual field. The upward-facing eyes allow the Barreleye fish to see silhouettes of prey or predators against the faint light filtering down from the surface. It’s like a built-in periscope for scanning the world above, allowing it to spot the bioluminescent glow of jellies or small fish that meander above it.
In 2009, researchers at the Monterey Bay Aquarium Research Institute elucidated a longstanding mystery surrounding the barreleye. For many years, marine biologists were under the impression that these specialized eyes were immobile and only provided the fish with a limited, tunnel-vision perspective, focused solely on the waters above its transparent head. Such a constraint would significantly limit the fish’s situational awareness, making it highly dependent on what occurs directly above it for both prey detection and predator evasion.
However, a groundbreaking paper by researchers Bruce Robison and Kim Reisenbichler overturned this conventional wisdom. Their findings reveal that the eyes of the barreleye fish are not static but can actually rotate within a transparent protective shield that envelops the fish’s head. This adaptation enables the fish not only to look upwards to identify potential prey but also to focus forward, thereby expanding its field of vision and facilitating more effective foraging.
A remotely operated vehicle or ROV named Doc Ricketts (MBARI)
Robison and Reisenbichler conducted their research using footage obtained from the Monterey Bay Aquarium Research Institute’s remotely operated vehicles (ROVs) to investigate the barreleye fish in the deep-sea regions adjacent to Central California. Situated at depths ranging from 600 to 800 meters (approximately 2,000 to 2,600 feet) beneath the ocean’s surface, the ROVs’ cameras typically captured images of these fish in a state of immobility, floating like zeppelins with their eyes radiating an intense green hue due to the illumination provided by the ROV’s powerful lighting system. The remotely captured video data also divulged a hitherto undocumented anatomical feature—namely, that the eyes of the barreleye fish are encased in a transparent, fluid-filled protective shield that encompasses the upper region of the fish’s cranial structure.
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The implications of this discovery extend beyond mere academic curiosity. Understanding the unique visual system of the barreleye fish provides crucial insights into the mechanisms of evolutionary adaptation. It showcases how even seemingly minor anatomical modifications can result in significant survival advantages in the highly competitive and challenging marine environment. Moreover, it challenges our existing perceptions and encourages scientists to revisit and reevaluate other long-standing assumptions in marine biology.
The Barreleye isn’t just a pair of eyes swimming around in the ocean, though. It has a suite of other adaptations to its challenging environment. For instance, it has large, flat fins that let it remain almost motionless in the water, conserving energy in an environment where every calorie counts. Also, it’s got a small mouth. This mouth is adapted to consume tiny organisms, like zooplankton, that are abundant in the deep ocean. So while the Barreleye may not be the apex predator down there, it has carved out its own unique niche.
Monterey Bay Aquarium Research Institute (MBARI) in Moss Landing, California
The fish also has what are called “lateral line canals” that are filled with fluid and are sensitive to changes in pressure. This allows the Barreleye to detect movement in the water, effectively giving it a “sixth sense” to sense prey or predators around it. Imagine you’re trying to navigate a pitch-black room—every little bit of extra information helps.
Despite its enigmatic nature, we know relatively little about its breeding habits, lifespan, or social interactions. Part of the reason is the difficulty in studying a creature that lives in such an extreme environment. Researchers have managed to capture only a few specimens, and observations in their natural habitat are relatively scarce.
While the Barreleye fish might look like a figment of a wild imagination, it’s very much a real creature, adeptly adapted to its harsh surroundings. It represents the myriad ways life can evolve to meet the unique challenges of extreme environments. As we continue to explore the depths of our oceans, who knows what other fantastical creatures we might find? That said, the Barreleye fish remains one of the most compelling arguments for the strange and wondrous biodiversity hidden in the ocean’s twilight zone, a testament to the endless creativity of evolution.
The stretch of water hugging the western shores of North America is a biological powerhouse, teeming with life and considered one of the most fertile marine environments on the planet. The California Current, originating from the colder regions up near British Columbia, sweeps its way down toward Baja California, extending laterally several hundred miles offshore into deep oceanic waters off the continental shelf. The current brings with it not just frigid waters but also a richness of life. As if choreographed, winds usually gust from the land towards the ocean, nudging surface waters away from the coastline. This displacement makes room for deeper, nutrient-packed waters to ascend, in a phenomenon aptly termed upwelling. Coastal upwelling is the dominant physical forcing affecting production in the California Current System.
This blend of icy waters and nutrient wealth sparks a bloom of marine vegetation, ranging from minuscule phytoplankton to sprawling underwater forests of kelp. These plants, often dubbed the “primary producers,” act as the nucleus of an intricate food web. The bounty includes thriving fisheries, generous populations of marine mammals like whales, seals, and dolphins, as well as a multitude of seabirds. The breadth of this fecund ecosystem can span an astonishing distance—up to 300 miles from the shoreline, enveloping a rich diversity of life within its aquatic embrace.
Phytoplankton are a critical part of the ocean’s food web.
The California Current System (CCS) is one of those natural phenomena that don’t often make headlines but quietly shape life as we know it on the West Coast. It’s like the unsung hero of the Pacific, affecting everything from marine biodiversity to our climate, even having a say in whether you’ll need to pack sunscreen or an umbrella for your beach day.
At its core, the California Current is a cold, southward-flowing oceanic current that starts from the Gulf of Alaska and hugs the western coastline of North America. Picture a river within the ocean, except this river is carrying cold, nutrient-rich water from the North Pacific all the way down to the southern tip of Baja California in Mexico. The California Current is part of a broader gyre system that also includes the North Pacific Current, the California Undercurrent, and the Davidson Current. Together, they create a dynamic dance of currents that provide a lifeline to a host of marine species and play a significant role in weather patterns.
The dynamics of the California Current result in abundant wildlife, like these common dolphins, off the coast of California.
The CCS owes its formation to a combination of factors like Earth’s rotation, the prevailing westerly winds, and the shape of the coastline. These elements work in concert to set up a sort of “conveyor belt” for water, funneling it down from higher latitudes. Over millions of years, this system has become a finely tuned natural mechanism that has shaped the ecology and climate of the region in profound ways.
The cold, nutrient-rich waters of the California Current serve as a veritable buffet for marine life. When we talk about nutrients, we’re primarily talking about nitrates and phosphates that act like fertilizer for phytoplankton, the microscopic plants at the base of the marine food web. As phytoplankton bloom, they become a food source for zooplankton, which in turn are gobbled up by larger fish. This cascade effect supports a rich, biodiverse ecosystem that includes everything from sardines and anchovies to humpback whales and even great white sharks. Even seabirds get in on the action, relying on the abundant marine life for nourishment.
The cold, nutrient-rich waters of the California Current serve as a veritable buffet for marine life.
But the California Current doesn’t stop at influencing marine biology; it’s a key player in regional climate as well. For example, the current helps moderate coastal temperatures by funneling cooler air inland. This has a ripple effect on weather patterns and even contributes to the famous “June Gloom” that Angelenos love to lament. Ever wonder why California’s coastal cities have relatively mild, Mediterranean climates while just a short drive inland can bring you much hotter conditions? Tip your hat to the CCS.
Climate change is, of course, the elephant in the room. A study published in the journal “Geophysical Research Letters” in 2019 highlighted a gradual weakening of the California Current due to warming ocean temperatures. As the current weakens, there’s potential for less upwelling, which means fewer nutrients reaching the surface. Less nutrient-rich water could be a gut punch to the marine food web, affecting fish populations and, by extension, the larger predators and human industries that rely on them.
The cold, nutrient-rich waters of the California Current serve as a veritable buffet for marine life.
Another concern is ocean acidification. The same cold, nutrient-rich waters that make the CCS a hotspot for marine life also make it more susceptible to acidification as they absorb more CO2 from the atmosphere. According to a 2020 study in the journal “Nature,” this could have far-reaching consequences for shell-forming organisms like mollusks and some types of plankton, which play crucial roles in the ecosystem.
So why is all of this important? Well, the California Current is a vital cog in the machinery of our planet. It supports rich biodiversity, influences climate, and even has economic implications, given the commercial fisheries that rely on its abundant marine life. A healthy CCS is good news for everyone, from the weekend beachgoer to scientists concerned about biodiversity.
But as we confront a changing climate, the CCS is a poignant reminder that even the most stable and established natural systems are not immune to disruption. Therefore, understanding it is not just an academic exercise, but a necessary step in safeguarding the fragile balance of life along the western edge of North America.
If you’ve ever looked out at the vastness of the ocean, you might think it’s a uniformly barren and flat landscape below the tranquil or tempestuous waves. But you’d be mistaken. Imagine for a moment a hidden world of underwater mountains, volcanoes that never broke the water’s surface, all lying in the mysterious depths of the ocean. These enigmatic formations are known as seamounts, and off the coast of California, they constitute an environment as fascinating as it is vital.
Interestingly, a lot of these seamounts off California are actually relatively new to science. According to Robert Kunzig and his book Mapping the Deep: “In 1984, a sidescan survey off southern California revealed a hundred uncharted seamounts, or undersea volcanoes, in a region that had been thought to be flat.”
The genesis of these structures begins with a geologic process known as plate tectonics. As tectonic plates move beneath the Earth’s crust, they create hotspots of molten rock. This magma escapes through weak points in the crust and solidifies as it reaches the cold seawater, gradually building up into an undersea mountain. After thousands of years, a seamount is born. Most of California’s seamounts are conical in shape, though erosion and other geological forces can turn them into more complex formations over time.
Each seamount is a world unto itself, with distinct mineral compositions, shapes, and ecosystems. Recent research has energized the scientific community. For instance, the Davidson Seamount is the most well-known of these volcanoes and was the first underwater peak to be named a seamount. The seamount is named for George Davidson, a British pioneering scientist and surveyor. Located about 80 km (50 miles) off the coast of Big Sur, it’s shaped like an elongated arrowhead made up of several parallel ridges of sheer volcanic cones. Most of these erupted about 10-15 million years ago, and are made up 320 cubic km of hawaiite, mugearite, and alkalic basalt, the basalt types commonly found along spreading ridges like the Mid-Atlantic Ridge.
Davidson Seamount, Wikipedia
The sheer number of seamounts only began to emerge when new detection methods were developed, including the ability to spot them from space. These underwater mountains are so massive that they create a gravitational pull, drawing seawater slightly toward their center of mass, much like the moon’s pull generates tides. Since seawater is incompressible, it doesn’t compress around the seamounts but instead forms slight bulges on the ocean surface. Satellites can detect these bulges, helping locate the hidden, basaltic peaks below. Satellite studies suggest that the largest seamounts—those over 5,000 feet—may number anywhere from thirty thousand to over one hundred thousand worldwide, with high concentrations in the central Pacific, Indian, and Atlantic Oceans, around Antarctica, and in the Mediterranean. Each of these seamounts is an underwater volcano, typically lining mid-ocean ridges, subduction zones, or one of the forty to fifty oceanic hot spots where the earth’s crust is thin and magma rises from the mantle.
Davidson Seamount is by far the best-studied of the many seamounts off the California coast. Stretching a sprawling 26 miles in length and spanning 8 miles across, this colossal seamount ranks among the largest known formations of its kind in U.S. territorial waters. Towering at a remarkable 7,480 feet from its base to its peak, the mountain remains shrouded in the depths, with its summit situated a substantial 4,101 feet beneath the ocean’s surface. Studies have indicated that some seamounts contain deposits of rare earth elements, which could have potential economic importance in the future.
A rorqual whale fall found near Davidson Seamount at a depth of 3,200 meters. Photo Credit: Chad King / OET, NOAA
Seamounts are biodiversity hotspots. Boasting an incredibly diverse range of deep-sea corals, Davidson Seamount serves as a kind of underwater Eden. Often referred to as “An Oasis in the Deep,” this submerged mountain is a bustling metropolis of marine life, featuring expansive coral forests and sprawling sponge fields. But it doesn’t stop there—crabs, deep-sea fishes, shrimp, basket stars, and a host of rare and still-unidentified bottom-dwelling creatures also call this place home. The seamount is more than just a biologically rich environment; it’s a treasure trove of national importance for its contributions to ocean conservation, scientific research, education, aesthetics, and even history.
Map of seamounts along the California coast. (Marine Conservation Institute)
Perhaps the most astonishing discovery at Davidson Seamount occurred in 2018, when scientists discovered the “Octopus Garden,” the largest known aggregation of octopuses in the world. The garden is about two miles deep and was discovered by researchers on the research vessel (RV) Nautilus. The team of scientists initially spotted a pair of octopuses through a camera on a remotely operated vehicle (ROV). Amanda Kahn, an ecologist at Moss Landing Marine Laboratories and San Jose State University, who was on the Nautilus during the discovery, told Scientific American that after observing the pair for a bit, the operators started to drift away from the rocks to move on, but immediately saw something unusual. “Up ahead of us were streams of 20 or more octopuses nestled in crevices,” Kahn says.
Typically lone wanderers of the ocean, octopuses aren’t known for their social gatherings. So, when researchers stumbled upon more than just one or two of these creatures, they knew something out of the ordinary was afoot. Swiftly pivoting from their original plans, the team zeroed in for a closer look. What they found was a community of these grapefruit-sized, opalescent octopuses, along with something even more mysterious—unusual shimmers in the surrounding water, hinting at the existence of some kind of underwater fluid seeps or springs. It turns out the octopuses migrate to deep-sea hydrothermal springs to breed. The females brood their eggs in the garden, where it is warmer than surrounding waters.
“This Octopus Garden is by far the largest aggregate of octopuses known anywhere in the world, deep-sea or not,” James Barry, a benthic ecologist at the Monterey Bay Aquarium Research Institute told Scientific American. Barry is the leader of the new study, published on in August in Science Advances, that reveals why the animals are gathering. The researchers have observed over 5,700 Pearl octopuses (Muusoctopus robustus) breeding near Davidson Seamount, 3,200 meters below the ocean’s surface. In this deep-sea nursery, octopus mothers keep their eggs warm in 5°C waters flowing from a hydrothermal spring. The water is more than 3°C warmer than the surrounding ocean. This added warmth accelerates the embryos’ development, allowing them to fully mature in just under two years on average.
The Octopuses Garden was studied over the course of 14 dives with MBARI’s remotely operated vehicle (ROV) Doc Ricketts. It is within the Monterey Bay National Marine Sanctuary, so it is federally protected against exploitation and extraction., although many scientists are concerned that global warming could end up having a deleterious impact on the biological life found around seamounts.
So far scientists have discovered other octopus gardens around the globe. There are four deep-sea octopus gardens in total. Two are located off the coast of Central California and two are off the coast of Costa Rica.
New technological advancements like Remotely Operated Vehicles (ROVs) have recently opened doors to discoveries we never thought possible. Cutting-edge imaging technology has finally given us the ability to capture strikingly clear and high-resolution pictures from this enigmatic deep-sea habitat. These vivid images provide both the scientific community and the general public with unprecedented peeks into the lives of rare marine species inhabiting this mostly cold and dark underwater world.
Depth color-coded map of Monterey Canyon. (Monterey Bay Aquarium Research Institute)
Davidson Seamount’s proximity to the rich educational and research ecosystem in the Monterey Bay area. One of the world’s preeminent ocean research organizations, the Monterey Bay Research Institute (MBARI), is located in Moss Landing, California, right at the spot where the magnificent Monterey Canyon stretches away from the coast for hundreds of miles. This geographic boon makes it easier for interdisciplinary teams to join forces, enriching our understanding and educational outreach related to this uniquely captivating undersea landscape.
Beyond being hubs of biodiversity, seamounts also serve as waypoints for migratory species. Just like rest stops along a highway, these underwater mountains provide food and shelter for creatures like whales and tuna on their long journeys. This makes seamounts critical for the health of global marine ecosystems. Additionally, understanding seamounts could give us insights into climate change. They play a role in ocean circulation patterns, which, in turn, affect global weather systems. They are also excellent “archives” of long-term climate data, which could help us understand past climate variations and predict future trends.
Advances in underwater technology, like ROVs, autonomous submersibles and better remote sensing methods, are making it easier to study these mysterious mountains. But many questions still remain unanswered. For instance, how exactly do seamount ecosystems interact with surrounding marine environments? What are the long-term impacts of human activities, like deep-sea mining or overfishing, on these fragile habitats? And what untapped resources, both biological and mineral, lie waiting in these submerged summits?
A time-lapse camera designed by MBARI engineers allowed researchers to observe activity at the Octopus Garden between research expeditions. (Photo: MBARI)
We can wax poetic about the mysteries of seamounts, but understanding them better is crucial for the preservation of marine ecosystems and for equipping ourselves with the knowledge to tackle environmental challenges. So, the next time you look out over the ocean, consider the hidden worlds lying beneath those waves—each a bustling metropolis of life and a potential goldmine of scientific discovery.
Towering over Los Angeles like quiet guardians, the San Gabriel Mountains stretch across the northern edge of the city, keeping watch over the busy sprawl below. More than just a dramatic barrier, these mountains are packed with stories of shifting earth, ancient rock, wild weather, and the people who’ve passed through them for thousands of years. They are also a primary source of Southern California beaches. They’re not just a backdrop; they’re a vital part of the region’s identity, full of science, history, and amazing nature.
Part of the Transverse Ranges, a rare east-west trending group of mountains in California, the San Gabriels rise abruptly from the San Gabriel Valley and form a kind of barrier between L.A. and the Mojave Desert. Framed by Interstate 5 to the west and Interstate 15 to the east, the range is anchored on its north side by the famous San Andreas Fault, where the Pacific and North American tectonic plates constantly grind against each other. That ongoing crush is what helped push these peaks up so quickly. Geologically speaking, they’re growing surprisingly quickly.
Side note: The Transverse Ranges also include the Santa Monica Mountains, San Bernardino Mountains, Santa Ynez Mountains, Topatopa Mountains, Tehachapi Mountains, Santa Susana Mountains, and Sierra Madre Mountains.
Inside the range you’ll find the Angeles and San Bernardino National Forests, along with the San Gabriel Mountains National Monument, first established in 2014 and significantly expanded in 2024 to protect more than 450,000 acres of rugged, biodiverse, and culturally significant terrain. (There is excellent hiking in these mountains.) These protected areas include steep canyons, chaparral, rare wildlife, and sites that are important to the history and traditions of Native American communities.
A pool of water from the Arroyo Seco in the San Gabriel Mountain (Erik Olsen)
The rocks here are some of the oldest in the region, but the mountains also tell stories from more recent times: gold miners, early astronomers, hikers, and wildfire researchers. The San Gabriels help shape the weather, store precious snowpack, and remind everyone in L.A. that nature is always nearby and always in motion.
The San Gabriel Mountains offer an impressive rise in elevation, they really kind of explode out of the earth. While the foothills begin at nearly sea level, the highest point in the range is Mount San Antonio, but most people know it as Mount Baldy because, let’s face it, with its distinctive, treeless summit, it looks kind of bald. This peak reaches an altitude of 10,064 feet (3,068 meters). The quick transition from the bustling city to towering peaks is part of the magic of these mountains, a dramatic wall standing guard over downtown Los Angeles.
While the San Gabriels are much smaller in terms of length than, say the Appalachians, they are significantly taller on average. The highest peak in the Appalachians, Mount Mitchell in North Carolina, reaches 6,684 feet (2,037 meters). That’s considerably lower than Mount Baldy in the San Gabriels. The San Gabriels, therefore, boast higher peaks even though they cover a smaller area. However, compared to the Appalachians, which are thought to be billions of years old, the San Gabriel Mountains are relatively young, geologically speaking, and are characterized by rugged and steep features. In essence, being younger, they’ve undergone less erosion.
San Gabriel mountains from La Cañada Flintridge (Photo: Erik Olsen)
To understand the story of the San Gabriel Mountains, we need to embark on a temporal journey spanning millions of years. The mountains’ tale starts about 100 million years ago, during the Mesozoic Era, when massive tectonic plates—the Pacific and North American plates—began to converge. The interaction of these tectonic plates was dramatic, with the Pacific Plate subducting, or diving beneath, the North American Plate. This subduction caused the rocks to melt and, over time, rise to form granitic masses known as plutons.
Rocks of a roadcut in the San Gabriel Mountains (Erik Olsen)
As the ages rolled on, these plutons were uplifted, and the erosion of the surrounding softer rocks exposed the granitic cores, giving birth to the San Gabriel Mountains we see today. The primary rock composition of these mountains is granite, with large-grained crystals of feldspar, quartz, and mica that glitter when the sun kisses their surfaces. These mountains also feature significant deposits of sedimentary rocks, particularly in the lower elevations, which date back to the Mesozoic and Cenozoic eras.
The drainage system of the San Gabriel Mountains is defined by numerous canyons, streams, and arroyos that channel water down from the high elevations into the valleys below. The Arroyo Seco, one of the most well-known waterways, begins near Mount Wilson and flows southwest through Pasadena before merging with the Los Angeles River. Other important streams include the Big Tujunga Creek, which cuts through the mountains to feed into the San Fernando Valley, and the San Gabriel River, which drains much of the range’s eastern side. These waterways are seasonal, swelling during winter rains and spring snowmelt, and often run dry during summer months. Their canyons have been carved by the relentless forces of erosion, creating deep ravines that are vital for wildlife and plant habitats.
Heavy rains cause flooding in the Arroyo Seco near Pasadena. (Erik Olsen)
The San Gabriel Mountains play a critical role in the watershed that serves the greater Los Angeles area. Rain and snowmelt from the mountains replenish groundwater basins and feed into reservoirs, such as the San Gabriel Reservoir and the Morris Reservoir, which are essential for water supply. These mountains act as a natural guidance system, capturing precipitation and funneling it into the region’s aquifers and rivers, supporting both the municipal water supply and flood control efforts. The watershed is crucial for Los Angeles, which depends on these local sources of water to supplement imported supplies from distant regions like the Colorado River and the Owens Valley. The mountain runoff helps maintain the flow of the Los Angeles River, contributing to the city’s efforts to recharge groundwater and ensure a reliable water supply in this semi-arid region.
When it rains it pours, and sometimes causes landslides
Flood control has long been a central concern in managing the water systems of the San Gabriel Mountains, particularly due to the area’s vulnerability to intense, episodic storms. The steep slopes of the mountains funnel rainwater rapidly into urban areas, leading to a heightened risk of flash floods and debris flows. Over time, this led to the construction of a vast network of catchment basins, dams, and debris basins at the foot of the mountains. These basins are designed to capture stormwater runoff, preventing the overflow of water into densely populated areas and managing the sediment and debris that comes with mountain runoff, which can clog waterways and exacerbate flooding.
Catchment basins in the San Gabriel Mountains are critical for controlling debris flows that occur during and after heavy rains, which can be particularly dangerous in areas where wildfires have stripped the landscape of vegetation. When intense rainstorms hit the steep, fire-scarred slopes, they trigger massive torrents of mud, boulders, and tree debris that rush down the mountain canyons toward the urban foothills. These debris flows can overwhelm creeks and spill into residential neighborhoods, causing widespread destruction. The catchment basins are designed to trap this debris before it reaches populated areas, but their effectiveness depends on regular maintenance and clearing. When these basins fill up too quickly or are not properly maintained, debris can overtop them, leading to significant flooding and property damage.
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A stark example of the dangers posed by debris flows occurred in Montrose in 1934. Following a series of intense storms in the aftermath of the New Year’s Day floods, massive debris flows roared out of the San Gabriel Mountains, devastating the communities of Montrose, La Crescenta, and Tujunga. The floods and debris flows buried homes and roads under several feet of mud and debris, killing at least 45 people. The Montrose landslide became a tragic reminder of the risks associated with living near the San Gabriel Mountains, particularly in the face of severe weather. This event spurred greater investments in flood control infrastructure, including the construction of more robust debris basins to mitigate the effects of future storms.
The San Gabriel Mountains aren’t just a spectacle of natural processes; they’ve also been a silent witness to numerous significant historical events. The grave of Owen Brown can be found in the mountains just outside of La Canada Flintridge. Owen was the third son of abolitionist John Brown, and has a resting place that has stirred intrigue and speculation for generations. Owen’s grave has become a kind of pilgrimage site for those interested in American history.
Locals gather to celebrate the installation of a gravestone honoring abolitionist Owen Brown on January 29, 1898, nearly a decade after his death. Photo: Brown family and Paul Ayers.
Owen Brown was a fervent abolitionist like his father and participated in the famous raid on Harpers Ferry. After the tumultuous events that marked his early life, he moved to California, seeking solace in the west. He settled near El Prieto Canyon and lived a relatively secluded life. After his death in 1889, he was buried on a hillside overlooking the canyon, and his grave was marked with a simple headstone. Over time, nature, vandals, and other factors led to the original headstone’s disappearance, adding a layer of mystique to the grave’s location. However, in 2019, a replica of the gravestone was installed.
Mount Wilson is another historical wonder in the range. Standing at a towering height of 5,710 feet, it’s not just its elevation that sets Mt. Wilson apart. In the early 20th century, the Mount Wilson Observatory was established, and it soon became a hub of astronomical discoveries. It was here that Edwin Hubble, using the Hooker Telescope, provided evidence of the expansion of the universe—a groundbreaking observation that eventually led to the Big Bang Theory.
Infrastructure Marvel: The Angeles Crest Highway The human connection to the San Gabriel Mountains was further cemented with the construction of the Angeles Crest Highway in the 1930s. Spanning approximately 66 miles, this scenic byway was a colossal engineering challenge. Its creation provided access to previously remote regions and breathtaking panoramic views that today lure thousands of tourists and nature enthusiasts. The highway is also one of the highest in Southern California, with a summit of 7,903 feet at the Dawson Saddle.
Angeles Crest Highway roadcut (Photo: Erik Olsen)
Driving on the Angeles Crest Highway is an experience that’s both thrilling and a bit nerve-wracking. Winding and twisting through the mountains, you can come across steep drop-offs, sharp turns, and narrow lanes. With elevation changes ranging from around 1,200 feet to more than 7,900 feet, it’s a route that demands respect and attention from those behind the wheel.
Flora, Fauna, and Natural History: A Biodiversity Hotspot Beyond geology and history, the San Gabriel Mountains are a treasure trove of biodiversity. The montane environment, with its varied elevation and climate zones, has given rise to a rich tapestry of flora and fauna. Iconic trees like the Jeffrey pine, Coulter pine, and California black oak adorn the landscape. Wildflowers paint the meadows in vibrant hues, from the golden yarrow to the scarlet larkspur.
The fauna is just as diverse, with animals like the California condor, bighorn sheep, and mountain lions roaming the rugged terrain. The waters that trickle and rush down these mountains are home to arroyo chubs and Santa Ana suckers.
The California condor is known to inhabit the San Gabriel range
Protection of this vital ecosystem came in the form of the San Gabriel Mountains National Monument designation in 2014, ensuring that the mountains’ rich biodiversity and cultural significance will be preserved for generations.
The San Gabriel Mountains are more than just a scenic backdrop. They reflect the Earth’s active geology, hold key historical moments, and support diverse ecosystems. Amid growing urbanization, these mountains remain a lasting reminder of the interconnectedness of life, history, and natural forces.
Perched atop a lofty peak in the San Gabriel Mountains of California sits a historic treasure, one of the great astronomical tools of the 20th century: the Mt. Wilson Observatory. For more than 100 years, it has been a centerpiece for major astronomical discoveries, playing a pivotal role in our understanding of the universe. The observatory, with its rich history shaped by devoted scientists, advanced technology, and revolutionary discoveries, stands as a testament to humanity’s relentless pursuit of knowledge.
The story of the Mt. Wilson Observatory begins with the visionary astronomer George Ellery Hale. Recognizing the importance of location, Hale selected Mt. Wilson for its elevation of 5,710 feet and its proximity to the Pacific Ocean, which provided consistently stable, clear skies—perfect conditions for astronomical observations. In 1904, he installed the first telescope at the site, the Snow Solar Telescope, specifically designed for studying the Sun. This telescope marked the beginning of groundbreaking solar research at the observatory and set the stage for future advancements in astronomy.
Many brilliant minds walked the halls and explored domes of Mt. Wilson, but few shone as brightly as Edwin Hubble. In the 1920s, using the Hooker Telescope – then the largest in the world – Hubble made two groundbreaking discoveries:
Before Hubble’s observations at Mt. Wilson, the prevailing belief was that our galaxy, the Milky Way, constituted the entirety of the universe. The existence of other galaxies was not yet confirmed, and what we now know as galaxies were often referred to as “nebulae” and thought to be part of the Milky Way.
Hubble’s groundbreaking discovery in 1923-1924, using the 100-inch Hooker telescope at Mt. Wilson, revealed that the Andromeda Nebula (now known as the Andromeda Galaxy) was far beyond the Milky Way, providing the first concrete evidence that the universe extended far beyond our own galaxy. This discovery fundamentally altered our understanding of the cosmos, leading to the realization that the universe is vast and filled with countless galaxies.
Expanding Universe
Using the powerful Hooker telescope once again, Hubble carefully observed distant galaxies and made a groundbreaking discovery: these galaxies were moving away from us. Even more astonishing was that the farther a galaxy was, the faster it was receding. This finding provided clear evidence that the universe itself was expanding. Hubble’s revelation shattered the long-held belief in a static universe and laid the groundwork for the Big Bang theory, suggesting that the universe had a specific beginning and has been expanding ever since. Through Hubble’s meticulous observations, humanity gained a new understanding of a dynamic, ever-evolving cosmos, far more vast and mysterious than anyone had previously imagined.
Edwin Hubble
Many other scientists have also made major discoveries at Mt. Wilson. One luminary, Harlow Shapley, used the observatory to gauge more specifically our place in the Milky Way. Before Shapley, Earth was believed to be at the galaxy’s center. However, through his observations of globular clusters, he pinpointed our more humble location on a distant spiral arm.
Another notable scientists who made significant contributions at Mt. Wilson Observatory was Walter Baade. Baade, a German-American astronomer, played a key role in refining our understanding of the universe by studying stars in different populations. During World War II, when Los Angeles experienced blackout conditions, Baade took advantage of the clearer skies at Mt. Wilson to observe celestial objects with unprecedented clarity. He discovered that there were two distinct types of stars in the Milky Way, which led to the realization that galaxies had different stellar populations. This breakthrough allowed Baade to correct the scale of the universe, doubling the previously estimated size of galaxies and distances to them. His work helped refine Hubble’s expanding universe theory and provided a deeper understanding of the evolutionary stages of stars. Baade’s observations were critical in the advancement of modern cosmology and our comprehension of the vastness of space.
Instruments of Enlightenment
Over the years, Mt. Wilson has housed a suite of powerful telescopes:
The Hooker Telescope: At 100-inches, it was the world’s largest when it was installed in 1917. It’s the very instrument Hubble used for his revolutionary work.
The Snow Solar Telescope: The observatory’s inaugural instrument remains crucial for solar studies.
The CHARA Array: The Center for High Angular Resolution Astronomy array is an impressive configuration of six telescopes that function as an interferometer. It allows for sharper images of stars than even the Hubble Space Telescope. The CHARA Array has a spatial resolution equivalent to a single telescope 331 meters (over 1000 ft) in diameter. Light from each of the six telescopes is transported through fiber optics to a special beam-combining room.
Not only has Mt. Wilson been instrumental in observing distant stars, but it also has a unique device: the Snow Horizontal Solar Telescope. This apparatus, combined with the spectrograph, was used to study the sun’s magnetic fields. It has since been fundamental in understanding solar cycles and the impact of solar phenomena on Earth’s climate.
Mt. Wilson Observatory
In 2020, the Bobcat Fire, the second largest fire on record in Los Angeles County to date, burned over 115,000 acres and was active for more than three months. Annually, the team at Mount Wilson Observatory takes measures against potential forest fires, removing fire-hazardous invasive plants and ensuring their extensive water tanks are full for the fire suppression system. Just a few months prior to the blaze, they had fitted new high-capacity hydrants. These proactive steps played a pivotal role in safeguarding the Observatory when the Bobcat Fire flames approached within a mere 20 feet of its perimeter. A dozen fire squads, each consisting of 40 to 50 firefighters from various units, tirelessly worked day and night to protect this cherished landmark.
Scene at Mt. Wilson after the 2020 Bobcat Fire (Erik Olsen)
Visitors to the Mt. Wilson Observatory have a rare chance to not only tour the grounds but also look through the same telescopes that revolutionized astronomy. Public “Telescope Nights” offer the exciting opportunity to observe the night sky through the famous 60-inch or 100-inch telescopes, the latter being the largest in the world open to the public. These sessions allow people to view celestial objects like planets, star clusters, and nebulae in stunning detail. Reservations are necessary for these events, as spots fill up quickly due to high demand. Additionally, private group sessions and special events can be arranged, providing an unforgettable, up-close experience with the universe. Guided tours are also available for those who want to dive into the observatory’s rich history, tracing the steps of astronomers who made some of the greatest discoveries of the 20th century.
“Here in Pasadena, it is like Paradise. Always sunshine and clear air, gardens with palms and pepper trees and friendly people who smile at one and ask for autographs.” – Albert Einstein (U.S. Travel Diary, 1930-31, p. 28)
Albert Einstein is often associated with Princeton, where he spent his later years as a towering intellectual figure, and with Switzerland, where he worked as a young patent clerk in Bern. It was in that spartan, dimly lit office, far from the great universities of the time, that Einstein quietly transformed the world. In 1905, his annus mirabilis or “miracle year,” he published a series of four groundbreaking papers that upended physics and reshaped humanity’s understanding of space, time, and matter. With his insights into the photoelectric effect, Brownian motion, special relativity, and the equivalence of mass and energy (remember E=mc2?), he not only laid the foundation for quantum mechanics and modern physics but also set in motion technological revolutions that continue to shape the future. Pretty good for a guy who was just 26.
Albert Einstein spent his later years as a world-famous scientist traveling the globe and drawing crowds wherever he went. His letters and travel diaries show how much he loved exploring new places, whether it was the mountains of Switzerland, the temples of Japan, or the intellectual circles of his native Germany. In 1922, while on his way to accept the Nobel Prize, he and his wife, Elsa, arrived in Japan for a six-week tour, visiting Tokyo, Kyoto, and Osaka.
But of all the places he visited, one city stood out for him in particular. Pasadena, with its warm weather, lively culture, and, most importantly, its reputation as a scientific hub, had a deep personal appeal to Einstein. He visited Pasadena during the winters of 1931, 1932, and 1933, each time staying for approximately two to three months. These stays were longer than many of his other travels, giving him time to fully immerse himself in the city. He spent time at Caltech, exchanging ideas with some of the brightest minds in physics, and fully embraced the California experience, rubbing elbows with Hollywood stars (Charlie Chapman among them), watching the Rose Parade, and even tutoring local kids. Einstein may have only been a visitor, but his time in Pasadena underscores how deeply rooted science was in the city then, and how strongly that legacy endures today. Pasadena remains one of the rare places in the country where scientific inquiry and creative spirit continue to thrive side by side. Pasadena was among the earliest cities to get an Apple Store, with its Old Pasadena location opening in 2003.
Einstein’s residence at 707 South Oakland Avenue in Pasadena, where he stayed his first winter in California (CalTech Archives)
Few scientists have received the public adulation that Einstein did during his winter stays in Pasadena. As a hobbyist violinist, he engaged in one-on-one performances with the conductor of the Los Angeles Philharmonic. Local artists not only painted his image and cast him in bronze but also transformed him into a puppet figure. Frank J. Callier, a renowned violin craftsman, etched Einstein’s name into a specially carved bow and case.
During his first winter of residence in 1931, Einstein lived in a bungalow at 707 South Oakland Avenue. During the following two winters, he resided at Caltech’s faculty club, the Athenaeum, a faculty and private social club that is still there today.
Yet, the FBI was keeping a watchful eye on Einstein as well. He was one of just four German intellectuals, including Wilhelm Foerster, Georg Nicolai, and Otto Buek, to sign a pacifist manifesto opposing Germany’s entry into World War I. Later, Einstein aligned himself with Labor Zionism, a movement that supported Jewish cultural and educational development in Palestine, but he opposed the formation of a conventional Jewish state, instead calling for a peaceful, binational arrangement between Jews and Arabs.
In front of the Athenaeum Faculty Club, Caltech, 1932. (Courtesy of the Caltech Archives.)
After his annus mirabilis in 1905, Einstein’s influence grew rapidly. In 1919, his theory of relativity was confirmed during a solar eclipse by the English astronomer Sir Arthur Eddington. The announcement to the Royal Society made Einstein an overnight sensation among the general public, and in 1922, he was awarded the 1921 Nobel Prize in Physics. While teaching at the University of Berlin in 1930, Arthur H. Fleming, a lumber magnate and president of Caltech’s board, successfully persuaded him to visit the university during the winter. The visit was intended to remain a secret, but Einstein’s own travel arrangements inadvertently made it public knowledge.
Einstein speaking at the dedication of the Pasadena Junior College (now PCC) astronomy building, February 1931. (Courtesy of the Caltech Archives)
After arriving in San Diego on New Year’s Eve 1930, following a month-long journey on the passenger ship Belgenland, Einstein was swarmed by reporters and photographers. He and his second wife, Elsa, were greeted with cheers and Christmas carols. Fleming then drove them to Pasadena, where they settled into the bungalow on S Oakland Ave.
Albert Einstein and his violin (Caltech Archives)
During their first California stay, the Einsteins attended Charlie Chaplin’s film premiere and were guests at his Beverly Hills home. “Here in Pasadena, it is like Paradise,” Einstein wrote in a letter. He also visited the Mt. Wilson Observatory high in the San Gabriel Mountains. Einstein’s intellectual curiosity extended far beyond his scientific endeavors, leading him to explore the Huntington Library in San Marino, delighting in its rich collections. At the Montecito home of fellow scientist Ludwig Kast, he found comfort in being treated more as a tourist than a celebrity, relishing a brief respite from the spotlight.
In Palm Springs, Einstein relaxed at the winter estate of renowned New York attorney and human rights advocate Samuel Untermeyer. He also embarked on a unique adventure to the date ranch of King Gillette, the razor blade tycoon, where he left with a crate of dates and an intriguing observation. He noted that female date trees thrived with nurturing care, while male trees fared better in tough condition: “I discovered that date trees, the female, or negative, flourished under coddling and care, but in adverse conditions the male, or positive trees, succeeded best,” he said in a 1933 interview.
Not exactly relativity, but a curiosity-driven insight reflecting his ceaseless fascination with the world.
During his three winters in Pasadena, Einstein’s presence was a source of intrigue and inspiration. Students at Caltech were treated to the sight of the disheveled-haired genius pedaling around campus on a bicycle, launching paper airplanes from balconies, and even engaging in a heated debate with the stern Caltech president and Nobel laureate, Robert A. Millikan, on the steps of Throop Hall. Precisely what they debated remains a mystery. (Maybe something about the dates?)
Einstein with Robert A. Millikan, a prominent physicist who served as the first president of Caltech from 1921 to 1945 and won the Nobel Prize in Physics in 1923. (Courtesy of the Caltech Archives.)
During his final winter in California, a near-accident led the couple to move into Caltech’s Athenaeum. His suite, No. 20, was marked with a distinctive mahogany door, a personal touch from his sponsor, Fleming. In 1933, as Nazi power intensified in Germany, Einstein began searching for a safe place to continue his work. Although Caltech made an offer, it was Princeton University‘s proposal that ultimately won him over. Einstein relocated to Princeton that same year, where he played a significant role in the development of the Institute for Advanced Study and remained there until his death in 1955.
Suite No. 20, Einstein’s mahogany door at the Caltech Athenaeum
Today, a large collection of Einstein’s papers are part of the Einstein Papers Project at Caltech. And Einstein’s suite at Caltech’s Athenaeum, still displaying the mahogany door, serves as a physical reminder of his visits.
During his third and final visit to Caltech in 1933, Hitler rose to power as Chancellor of Germany. Realizing that, as a Jew, he could not safely return home, Einstein lingered in Pasadena a little longer before traveling on to Belgium and eventually Princeton, where he received tenure. He never returned to Germany, or to Pasadena. Yet he often spoke fondly of the California sunshine, which he missed, and in its own way, the sunshine seemed to miss him too.
