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Earthquake Experts Modeled 1,000 Years of Activity in California—What They Found Now Has Scientists Concerned

California could be due for a major earthquake in the near future, according to concerning new models based on data comprising 1,000 years of quake activity on the West Coast.

According to recent findings, tectonic stress has quietly been building in California to levels not seen since the last major earthquake in the region, which bore a magnitude of 7.9 and struck the West Coast nearly 170 years ago.

That event, known as the Fort Tejon earthquake, affected the greater Los Angeles area, and since the time of those historic rumblings, researchers have grown increasingly concerned about a period of seismic silence that could point to the likelihood of an event of similar magnitude at some point in the future.

The potentially concerning new forecast was detailed in a recent study by an international team of researchers led by Dr. Liliane Burkhard of the Division of Space Research and Planetary Sciences (WP) at the Physics Institute of the University of Bern, which focused on historic earthquake data as a means of gauging current stress loading at Cajon Pass.

The study, published in the Journal of Geophysical Research: Solid Earth, indicates tectonic stress levels that are now believed to exceed the highest seen during the years the team surveyed.

The “Earthquake Gate” at Cajon Pass

The researchers aimed to investigate stress that has slowly built along the San Andreas and San Jacinto faults and incorporated what they likened to an “earthquake gate” at Cajon Pass, which, in their models, functioned like a point of control that governed the size of earthquakes and whether they could spread to both systems.

For their research, they used a four-dimensional earthquake cycle model that allowed them to replicate certain processes both in spatial dimensions and across time.

Using a millennium of reconstructed earthquake data from the region based on geological information such as radiocarbon dates, unusual events recorded in dendrochronological data (i.e., information obtained from tree rings), and historical information sources, the team gave this to the model they devised.

Dr. Burkhard said the team’s simulation offered them a unique opportunity to better understand the ways stresses in the fault system build up over long periods of several centuries.

“By running the earthquake history of Southern California as a simulation, we can estimate the extent to which the fault system is already under stress today,” Dr. Burkhard said. The results of those simulations weren’t particularly promising either: according to Burkhard, current stress levels in the region are the highest they have been in 1,000 years, based on the data.

Concerning New Earthquake Data

The team also identified significant new information regarding the function of the so-called “earthquake gate” at Cajon Pass.

“The earthquake gate concept captures something important about how fault junctions work,” Burkhard said in a recent statement. “Cajon Pass doesn’t simply block or channel earthquakes: It responds to stress conditions, and those conditions change over centuries.”

Not only this, but Burkhard and her team also determined that a key element to these quakes involves not only the level of stress that accumulates at a single fault, but perhaps more significantly, the way stress between two systems can align. This is because, as the stress across a pair of faults rises together over longer periods, this appears to be most conducive to a large joint rupture comparable to the 1857 Fort Tejon earthquake.

Conversely, if stress levels are not in concert as they evolve, the team determined that this causes quakes that probably will not propagate beyond the junction.

In short, a more severe earthquake event today would entail a joint rupture that crosses the Cajon Pass, as opposed to one constrained either to the San Andreas or the San Jacinto Fault alone. Should such an event occur, it would likely impact one of the largest population centers, as well as a crucial infrastructure system that supplies energy and transportation to surrounding areas.

For Burkhard, “The question of when and how the next major earthquake will occur in this region is one of the most pressing problems in applied geoscience.” Based on the team’s findings, they say that their new modeling hopes to provide a much more complete picture of the science behind the factors that could lead to a major quake—conditions that could apply equally to other parts of the world as they do to California.

Burkhard adds that her team’s study is not intended merely as a prediction for when the next major earthquake could potentially occur, but also as a means of preparing for future quakes and mitigating their effects.

“What we can say is that the system is critically stressed and that physics-based models like ours give a clearer picture of the range of scenarios we should be prepared for,” Burkhard says. “This information is important for hazard assessment, infrastructure planning, and emergency preparedness.”

The team’s study, “Cajon Pass and the Southern San Andreas Fault System: Earthquake Cycle Stress Accumulation and Present‐Day Loading,” appeared in the Journal of Geophysical Research: Solid Earth.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

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2,600-Year-Old Underground Discovery Reveals a Mysterious Ancient Structure Hidden Below Egypt’s Nile Delta

A curious recent discovery has revealed a promising new underground archaeological find at the ancient site of Buto in Egypt’s Nile Delta.

Researchers who were testing a remote sensing technology designed to locate buried structures and other below-ground features reported the unique find earlier this year, which could be a previously undiscovered tomb or temple now believed to date as far back as 2,600 years.

The discovery was made at the Tell el-Fara’in site, more commonly known as Buto, which comprises the remains of an ancient city that thrived around 5,600 years ago during Egypt’s Predynastic period.

Origins of a Mystery

Buto underwent several periods of destruction and reassembly throughout its history, making it a significant focus of past archaeological work.

Some of the city’s oldest portions are currently entombed beneath several centuries’ worth of accumulated mud and soil, a factor that significantly complicates traditional excavations. To help them locate an ideal location for future excavation, the team employed an approach that combined SAR (Sentinel-1 GRD) satellite imagery with electrical resistivity tomography (ERT) measurements, which helped them pinpoint an ideal location to dig that would best enable an investigation of Buto’s settlement phases.

“Sentinel-1 (C-band) satellite imagery captured on May 5, 2018, was processed using SNAP software (version 9.0.0) to identify large-scale anomalies indicative of buried structures,” the team reports in a paper detailing their findings, which appeared in Applied Geophysics in March.

“Based on these detected anomalies, the locations for ERT profiles were strategically selected to maximize the likelihood of indicating significant subsurface features,” the team explained.

ERT technology is ideal for such carefully targeted excavation, since it relies on electrical currents placed into the ground, which researchers then use to collect data that helps them assemble a three-dimensional model of the buried structures. This imagery is generated based on differences in the way various materials either display electrical conductivity or resistance.

Buried Discoveries Emerge

Based on the team’s scans, the top three meters of the area revealed a distinctive layer of material, which the team judged to be broken pottery and debris—likely associated with Roman periods of occupation.

However, going further down in their scans, descending to a depth of approximately six meters, the team discovered something more intriguing: what appeared to be some kind of large buried structure.

Based on its depth, the team believes this unique structure is likely associated with the Saite period, which dates it to around 2,600 years ago. Although it remains unknown precisely what the structure is, or what its exact purpose may have been, one possibility is that it could be a large shrine, or even a tomb.

Uncovering Religious Artifacts

Following the initial discovery, the team undertook preliminary excavations of a small 10 x 10-meter area. This revealed walls constructed of mudbrick, as well as religious artifacts in locations that aligned with the team’s scans.

“The presence of a small offering basin along with numerous religious amulets depicting Egyptian deities such as Isis, Horus, Taweret, and Wadjet further supports the temple hypothesis,” the team writes in their study.

Buto site
Above: According to the recent paper’s authors, the figure above shows a “3D map for the Kom C area, the full surveyed region by ERT, the successive layers of a vertical section for the excavated area, and some of the artefacts found in the excavated square.” (Image Credit: Abouarab, Elfadaly, et al./Applied Geophysics).

Also among the religious artifacts uncovered at the site were a “remarkable bronze amulet with a suspension hole, representing Horus the child” as well as amulets featuring a crouching lion, an amulet of Anubis, and the remains of limestone statues “in sexual positions” along with “a faience plaque with relief carvings of Hathor on both sides.”

However, the team reports that one of the most significant artifacts recovered from this area of the excavation was a steatite scarab bearing the name of King Thutmose III, which the team believes “may have functioned as an amulet or seal.”

“Collectively, these artefacts indicate the presence of a religious site with strong cultic and ceremonial associations, further reinforcing the interpretation of the structure as a temple from the 26th Dynasty,” the team says.

Ongoing Excavations

While still in the early phases, the team’s discoveries so far help to validate the geophysical and remote sensing techniques that made the discovery possible. “The results of this study demonstrate the effectiveness of combining geophysical measurements and remote sensing data,” the team writes, adding that they provided “a very accurate vision in detecting buried settlements in a complex region.”

“3D inversion algorithms were particularly effective in delineating buried mudbrick walls and architectural structures, significantly enhancing our understanding of site formation processes,” the researchers add.

Going forward, the team recommends further ERT surveys, which may help to reveal additional information about the site’s deepest occupation levels. For the time being, the team believes the evidence in hand points to the interpretation of the site and its features as an ancient temple, and that evidence points to the possibility that another may be located nearby.

“Our findings suggest that, in addition to the known temple, another temple may remain buried under a thick clay layer, which will be investigated through extensive measurements in forthcoming studies,” the team writes.

The recent paper, “Multi-scale detection of buried archaeological elements across different occupation phases: an integrated approach using radar satellite imagery and electric resistivity tomography at Buto, northwestern Nile Delta of Egypt,” appeared in Applied Geophysics on March 10, 2026.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

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“We Must Strengthen Our Processes”: NASA Issues Update on ‘Antenna Mishap’ Involving Deep Space Station 14

NASA officials have completed an investigation into an incident that caused damage to a 70-meter radio frequency antenna last year.

The incident, which occurred at the Goldstone Deep Space Communications Complex near Barstow, California, affected the space agency’s Deep Space Station 14 (DSS-14), a 70-meter radio-frequency antenna, which currently remains offline awaiting repairs and system upgrades.

Joel Montalbano, acting associate administrator for NASA’s Space Operations Mission Directorate, emphasized that the agency “takes safety and any departure from established procedures seriously,” adding that investigations into the incident at Goldstone “made clear that we must strengthen our processes. We are acting on the investigation’s findings.”

Incident at Goldstone

The damage was caused last September 16, 2025, when the antenna reportedly over-extended during rotation during tracking for NASA’s Juno mission. Stress on the antenna’s cabling and support infrastructure, as well as damage to its fire-suppression system, is expected to cost between $4.1 and $4.6 million in repairs.

Fortunately, no injuries were reported at the time of the incident, and a Mishap Investigation Board was convened to investigate the underlying causes. Following on-site inspections, interviews, and reviews of technical documentation from NASA’s three Deep Space Network facilities, the results of the investigation were included in a report submitted in April, which also made recommendations on how to prevent future incidents.

Software Issues

A primary factor behind the incident had been what the reports’ authors characterize as “software weaknesses, human error, and an undetected failure in the antenna’s hydraulic limit system,” according to a recent NASA statement.

“Investigators determined an electrical issue at the antenna the previous day caused the control system to misreport the antenna’s rotation state, an issue that went unnoticed and triggered multiple limit-stops during the Juno track,” the statement added.

Over-rotation of the antenna resulted after flooding in the antenna base was spotted by operators, following troubleshooting efforts that accidentally bypassed safeguards in the system’s hardware and software.

Investigators also determined that the antenna’s hydraulic limit system had already been rendered inoperable before the September 16 incident, following damage sustained “in an undocumented prior incident.”

Modernization for Future Missions

On June 5, Montalbano emphasized that NASA plans to follow the guidance in the review board’s report, with a focus on ensuring greater adherence to procedures to help limit the likelihood of future mishaps.

“We will update and improve procedures, rebuild core in-house capabilities, and reinforce operational discipline across the Deep Space Network,” Montalbano said.

“NASA remains focused on learning from this and modernizing systems, so DSS-14 and the broader network are ready to support our ambitious future missions,” he added.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

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An Explorer Vanished Searching for a ‘Lost Civilization’ in the Amazon—Now Archaeologists Think They May Have Found It

In 1925, while exploring the remote jungles of the Amazon on a quest to uncover a fabled lost city, British explorer Percy Fawcett and his small expedition party vanished without a trace.

Fawcett, a noted geographer, artillery officer, cartographer, surveyor, and archaeologist, set off into the rainforest accompanied only by his son, Jack Fawcett, and Jack’s best friend, Raleigh Rimell. Their goal was to locate an ancient lost city rumored to exist in the heart of the Amazon that Fawcett and others called “The Lost City of Z.”

While Fawcett and his expedition crew’s fate remains unknown, new advancements in modern archaeological science, propelled by technologies that include unmanned aerial vehicles and LiDAR, are now revealing what could be the archaeological reality behind part of what the ill-fated British explorer sought.

“The reward is that we’re finally finding the ‘lost civilisation’ that explorers like Percy Fawcett were searching for a century ago,” says José Iriarte, a professor of archaeology at the University of Exeter, writing in a piece featured at The Conversation, though adding that such discoveries are now being made “by cajoling a drone rather than battering through jungle.”

LiDAR: Unearthing Lost Worlds Hidden from Time

For a time, archaeologists presumed that the Amazon rainforest was a vast wilderness that, while abundant in resources, would have been capable of supporting only small, scattered communities.

With the aid of modern technologies, those past ideas have gradually changed as new archaeological evidence continues to push researchers toward rethinking past assumptions. Among these technologies is advanced laser-mapping technology known as LiDAR (light detection and ranging), which archaeologists have put to great use in the last several decades to aid in uncovering evidence of surface features that were once either inaccessible or otherwise invisible during ground-based surveys.

Something else that LiDAR excels at is penetrating the dense forest of areas like the Amazon, enabling researchers to get unprecedented aerial views of the surface below the canopy, along with any structures that may have been left there by humans from long ago. The result has been evidence of sprawling ancient societies hidden beneath the cover of thick jungle, revealing the Amazon as a region that once supported large populations that existed in sophisticated, interconnected landscapes.

LiDAR Cotoca site Bolivia
The Cotoca site in Bolivia, revealed through LiDAR imagery (Image Credit: Prümers, Iriarte, et al./Nature/https://doi.org/10.1038/s41586-022-04780-4)

Rediscovering a ‘Lost Civilization’ in the Amazon

A particularly striking example of such discoveries involves the Llanos de Moxos region of northern Bolivia, where recent LiDAR surveys have revealed the presence of a sprawling archaeological site long hidden by dense jungle. Archaeologists believe the ancient settlement is linked to what is called the Casarabe culture, which would have thrived in the area sometime between A.D. 500 and 1400.

“The Casarabe organized into a hierarchy of four different sizes of settlements,” writes Professor Iriarte in his recent piece at The Conversation. “The biggest ones—the primary settlements—were as large as 3km² or 300 hectares.”

“That’s enough space for over 400 football pitches,” Iriarte notes, “suggesting that they could have accommodated substantial numbers of people.”

Unseen Evidence of an Ancient Amazonian Culture

Viewed from the ground, an observer who braved this dense region of Bolivian jungle might only see thick patches of forest separated by grassland savannahs.

That all changes when viewing LiDAR imagery obtained during aerial surveys, however. Through the sensitive detection capabilities afforded by laser pulses that can easily penetrate the dense vegetation, a lost world emerges—one the likes of which Percy Fawcett and other early explorers once only dreamed of rediscovering.

Researchers have now successfully identified a vast network of settlements at Llanos de Moxos, connected by raised causeways, canals, reservoirs, and engineered agricultural systems that cover an area of close to 20,000 square kilometers.

These complexes upend past thinking about the presence of isolated settlements in the region, and instead appear to show sites covering areas as large as three square kilometers, featuring monumental civic and ceremonial architecture, towering conical pyramids that ascend to heights of 20 meters, and the presence of massive U-shaped structures, which archaeologists believe had likely served as ceremonial structures that once hosted gatherings.

Unprecedented Scale of a Hidden World

Another surprising feature is the scale of the structures archaeologists have uncovered, which they say rivals some of the most well-known monuments like those of the ancient Tiwanaku civilization in the Andes.

Yet, unlike many densely packed ancient cities, the Casarabe landscape also differs in several ways: the unique variety of urbanism it reflects is suggestive of dispersed populations whose connected infrastructure also brought them together through ancient shared water management systems.

“It was clearly all planned and coordinated,” Iriarte explains, adding that the ancient builders at Llanos de Moxos engaged in precocious designs that were intended “not only as living spaces but for integrating the population across the region.” Similar architectural planning has been observed at other ancient sites around the world, which include those assembled by the ancient Maya of Central America, as well as the builders of Angkor across the world in Cambodia.

The “Dark Earth” Enigma

Beyond just architecture and clues to the way of life of these ancient societies, researchers are also gaining new insights into the agricultural practices of the early Amazonian world.

For many decades, scientists presumed that a major limiting factor on the region’s ability to sustain larger populations hinged on the presence of factors that included poor soils, seasonal flooding, droughts, and tropical diseases. However, mounting evidence suggests that the indigenous societies of the region were far from hindered by the landscape, and instead managed to transform and manage farmland at scales previously unimagined.

Along with sophisticated agricultural systems, ancient Amazonians were also capable of engineering remarkably fertile soils, known as Amazonian Dark Earths, which Iriarte says “combined charcoal, bone and waste materials with the existing poor-quality soil to make it fertile enough for widespread farming.”

“Amazonia had reclaimed vast expanses of seasonally flooded savannahs over several thousand years to create raised and drained field systems,” he adds, also noting the construction of extensive drainage networks and the cultivation of diverse crops such as maize. Rather than merely adapting to the rainforest, the ancient inhabitants of the Amazon actively reshaped it.

An Amazonian Archaeological Revolution

Thanks to similar LiDAR surveys that have recently been undertaken in nearby countries, including Ecuador’s Upano Valley, where thousands of structures linked by roads and organized according to highly structured settlement plans have been detected, the recent findings at Llanos de Moxos are one of the latest additions to a broader revolution in archaeology made possible through such exciting Amazonian discoveries.

In addition to Bolivia and Ecuador, researchers have also documented ceremonial earthworks, geometric enclosures, and sprawling ancient settlements in Colombia, Peru, and Brazil in recent years, all of which are challenging decades of past assumptions about ancient life in the Amazon.

Despite the recent advancements in our understanding, many questions remain unanswered. Among the questions archaeologists have are those related to how these ancient societies were governed, as well as what factors led to their decline, a fall which was precipitated by unknown factors that occurred before European arrival.

Possible contributing factors may include shifts in ancient climates, as well as environmental pressures. It is also possible that political changes or conflicts that emerged between neighboring societies may have played a role, which could have contributed to disruptions in trade networks that may have further weakened these once thriving societies.

Despite the remaining mysteries about these enigmatic cultures, one thing is becoming increasingly clear: the Amazon was far from being the unclaimed tropical wilderness many long believed it to be. In many ways, the fascination with lost cities and ancient civilizations that drove explorers like Percy Fawcett—and which led to his untimely fate—had more basis in reality than many historians, archaeologists, and explorers probably guessed.

As ongoing LiDAR surveys continue to expand across previously unexplored regions, archaeologists believe thousands more structures may still await discovery, suggesting that some of the Amazon’s greatest archaeological secrets remain hidden, but no longer kept entirely from view.

“What lies beneath the Amazon is not just a hidden past,” Iriarte says. “It is a reminder that even the most seemingly untouched landscapes can carry deep histories, waiting—sometimes just beneath our feet—to be revealed.”

Professor José Iriarte’s complete article appeared at The Conversation on June 8, 2026.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

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This Ancient Artifact Remained Unidentified for Decades—Now It’s Rewriting the History of One of Japan’s Early Iron Technologies

An iron artifact recovered by archaeologists may be the oldest of its kind ever found in Japan, according to new research.

Recovered during excavations at the Hayashi-Fujishima archaeological site in Fukui, the capital city of Fukui Prefecture, the artifact measures slightly more than an inch and a half across, just under an inch in width, and just a millimeter in thickness.

The presence of tiny, triangular teeth measuring up to 3 millimeters deep indicates the artifact’s use as an early saw, according to investigations by the Fukui Prefectural Archaeological Research Center, which recently announced the discovery.

While similar discoveries have been made in Japan, none are believed to be as old as this saw, which archaeologists have tentatively dated to the late Yayoi Pottery Culture Period, which thrived between the second and third centuries, making it the oldest known in the country.

Tomokatsu Uozu, Deputy Director at the Center, said the age of the discovery indicates the advancement of early iron technologies along the region’s coastal communities during the period.

“The artifact could be an important piece of evidence supporting the advancement of ironware culture along the Sea of Japan coast during the Yayoi period,” Uozu recently told The Asahi Shimbun.

Similar Discoveries in the Ancient East

The saw uncovered at the Hayashi-Fujishima archaeological site bears some similarities to saws from the same period that have been unearthed during past excavations in China.

Such similarities are important, since it is believed that the same iron processing techniques used in the creation of the saw from the Hayashi-Fujishima site originated in China, having been carried across the Korean Peninsula and eventually reaching northern Kyushu, where ancient traders carried it along the Sea of Japan to its eventual arrival at Fukui.

The saw recently showcased by the Fukui Prefectural Archaeological Research Center is only one example of the many artifacts recovered from the Hayashi-Fujishima site.

Identified Decades After Its Discovery

Past work at the site has uncovered additional iron artifacts, as well as stone tools, pottery, distinctive “magatama” and “kudatama” bead varieties, and a range of items during primary excavations, which were conducted during the late 1990s and early 2000s.

The site is believed to also host what remains of an ancient settlement dating to the Yayoi period, a period that was significant for the emergence of organized food production, as well as a unique element associated with the culture: the creation of distinctive, keyhole-shaped burial mounds.

However, it wasn’t until 2021, during restoration work with many of the artifacts retrieved from the site, that researchers first noticed something significant that had gone unnoticed decades earlier at the time of the artifact’s discovery: tiny serrations were present on one of its edges.

Further examination with the help of X-ray CT scan imaging confirmed the artifact’s identity as a triangular or “beak-shaped” saw, similar to other discoveries from later periods. At the time of its use, the complete saw would likely have measured up to five times the length of the remaining fragmentary portion.

Another notable feature of the saw is that the tip of the blade is bent, which archaeologists think may indicate that the saw was used for work involving fine crafting of wooden or stone items.

Breaking Earlier Records for Japan’s Oldest Saw

The discovery now overturns the previous oldest artifact of its kind known from the region, which was uncovered from a third-century burial mound in Hyogo Prefecture. That saw’s association with the Kofun Period, which thrived near the end of the third century, made it the oldest known at the time of its discovery.

Although additional studies are required, the team says that confirmation of the age of the Hayashi-Fujishima site’s saw would extend the timescales once again on the earliest use of such technologies by as much as a century.

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5,500-Year-Old Discoveries in a Remote Mountain Cave Reveal Evidence of Prehistoric Industry Linked to the Dawn of Metallurgy

Strange green stones, evidence of repeated ancient expeditions, hidden burials, and other discoveries have been made in a remote cave high in the Pyrenees mountains.

The findings were made in a cave located more than 7,300 feet above sea level, revealing evidence that ancient visitors repeatedly endured the hardships of climbing to such altitudes for a period spanning 2,000 years. The question for archaeologists had been why this cave seems to have held such importance.

Now, discoveries at the remote site could potentially alter our understanding of ancient European uses of mountain landscapes in prehistoric times. Of key importance, archaeologists have uncovered ancient hearths that contain small samples of green minerals, which point to ancient mining activities that likely supported ancient metallurgy in the region.

Two Millennia of Human Interest

For more than 2,000 years, ancient Europeans repeatedly traveled to this remote cave, leaving behind evidence of their visits that includes ancient hearths and even a child’s tooth, suggesting the possibility that there may even be hidden graves at the site.

Professor Carlos Tornero, a researcher with the Catalan Institute of Human Paleoecology and Social Evolution, says these discoveries are surprising, since past research suggested such areas would only have been occasionally traversed by humans during periods of migration, rather than becoming destinations.

Cave 338
The entrance to Cave 338 (Image Credit: Tornero, et al, Front. Environ. Archaeology/doi: 10.3389/fearc.2026.1811493)

“For a long time, high-mountain environments were seen as marginal, places prehistoric communities passed through occasionally,” said Tornero, who is the lead author of a new study detailing the findings.

That wasn’t the case with this Cave 338, as archaeologists now call it, which turned out to be a far more unique site.

“We found a really rich archaeological sequence, including multiple combustion structures and a very large number of green mineral fragments,” Tornero recently said. “We can’t say exactly how long people stayed each time, but the repeated use of the space and the density of remains suggest occupations that were short to medium in duration, but happening again and again over long periods of time.”

Evidence of an Ancient Copper Mining Industry

At Cave 338, initial excavations began with a small area spanning six square meters near the cave’s entrance. There, Tornero and the team uncovered evidence of human activity temporally associated with four distinctive layers.

In the most recent layer of human occupation, artifacts from historical periods were found, although in smaller numbers, which suggested that the cave’s use had likely decreased gradually with time. Similar limited use was evidenced in the cave’s deepest layers, where charcoal fragments were discovered with dates indicating human activity as far back as 6,000 years ago.

Within layers two and three, significantly more activity was discernible. Discoveries within these layers included nearly two-dozen hearths, many of which contained burned fragments of a green mineral that researchers believe may be malachite.

Pyrenees malachite
Possible malachite fragments from Cave 338 (Image Credit: Maria D. Guillén / IPHES-CERCA).

If confirmed, this is significant, since malachite is rich in copper and can be processed to extract the metal, meaning that ancient visitors to the cave may have visited the site specifically to mine this unique green mineral. Cave 338 would therefore represent a very high-altitude mining camp, which ancient Europeans somehow discovered and repeatedly visited.

When Fire Heats the Green Stone

Based on radiocarbon dating, hearths located in the site’s second layer are approximately 3,000 years old, while those in the layer directly beneath it date to between 4,000 and 5,000 years ago.

Dr. Julia Montes-Landa of the University of Granada, who was a co-author of the new paper, says that evidence suggests many of the fragments were thermally altered—in other words, they were intentionally exposed to fire—while some of the samples found at the site were not.

This, she argues, “clearly suggests that fire played an important role in their processing and that there was a deliberate intention behind it.”

“They weren’t burned by accident,” Montes-Landa says.

Another indication of ancient industrial activity at the site involves the placement of the hearths in layers two and three, many of which overlap, which strongly suggests reuse. However, more than one area containing overlapping hearths is present, which also suggests that while reuse occurred, it took place in successive periods of visitation throughout time.

Hidden Burials and Prehistoric Artifacts

In addition to ancient evidence of mining and thermal alteration of stone, within the site’s third layer, a small amount of human remains—an ancient baby tooth and a finger bone believed to have belonged to a child—were found.

Such scant remains do not provide context for the cause of death or whether the remains came from the same individual. However, it does point to the possibility of hidden burials that may exist in other portions of the cave.

In addition to human remains, prehistoric artifacts were found at the site, which date to the second millennium BC, including a shell pendant and another made from a bear’s tooth.

“The shell pendant is interesting because it has parallels in other sites in Catalonia, which suggests shared traditions or connections between different communities,” Tornero said. “The bear tooth pendant is much less common.”

“That might point to something more specific or symbolic, possibly linked to the local environment,” Tornero suggests.

Lingering Questions

Obviously, 338 held significance to ancient inhabitants of the region, since, despite the daunting trek reaching it would have required, humans clearly returned there over and over again for a period of at least two thousand years, although evidence of human presence at the location extends to as much as double that amount of time.

Going forward, Tornero, Montes-Landa, and their colleagues hope that future excavations may reveal additional clues about who had been coming here for so long, and what specifically attracted them to the cave.

Of key significance will also be confirmation that the mineral contains copper.

“The identification of the green mineral as malachite is still preliminary,” Tornero says, adding that ongoing research “will provide final answers shortly.”

Much work remains to be done at the site, and Tornero and his team plan to resume excavations there later this year.

“The excavation hasn’t yet reached the full depth of the site,” Tornero said, “so the sequence is not completely documented.”

“This summer we will continue the archaeological work,” Tornero added.

For now, Cave 338 already shows that even some of the most remote areas of the Pyrenees could have played significant roles in the way ancient humans utilized the land and its resources.

“As such, the site provides a key reference framework for understanding high-mountain occupation, resource exploitation and mobility dynamics in the Pyrenees during later prehistory,” the authors write in their recent paper.

The team’s paper, “Beyond 2,000 meters, first evidence of intense prehistoric occupation in the Pyrenees,” appeared in Frontiers in Environmental Archaeology.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

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