Geoglyphs are large-scale designs created on the ground surface, typically by removing or rearranging rocks, soil, or vegetation to produce figures visible from a distance or from above. They exist on every inhabited continent, span thousands of years, and range from geometric lines stretching hundreds of meters across Peruvian deserts to massive earthen enclosures hidden beneath Amazonian rainforest. The Nazca Lines of southern Peru are the most famous examples, but recent discoveries in Brazil, Kazakhstan, and elsewhere have reshaped how researchers think about these structures and the societies that built them.
How Geoglyphs Are Made
The word “geoglyph” covers a surprisingly wide range of construction methods. What unites them is scale and ground-level execution. In the arid coastal deserts of Peru, the most common technique involved removing the dark, oxidized surface stones to expose lighter-colored ground beneath. The contrast between the two layers produces lines, trapezoids, and figurative shapes visible from elevated vantage points. Some Nazca geoglyphs are “negative” in this sense, made by subtraction. Others are “positive,” built up from piles of gathered stones arranged in rows. One detailed photogrammetric survey of a single Nazca-period geoglyph recorded 127 stone piles making up the two parallel lines of the figure across a 138-meter segment.1Journal of Cultural Heritage. Combining Structure-from-Motion with high and intermediate resolution satellite images to document threats to archaeological heritage in arid environments
In the Amazon basin, the approach was entirely different. Pre-Columbian builders dug geometric ditched enclosures into the earth, creating what are essentially negative earthworks. Over 450 of these structures have been identified across roughly 13,000 square kilometers of Acre state in western Brazil.2PubMed Central. Impact of pre-Columbian “geoglyph” builders on Amazonian forests In Central Asia, builders took yet another path, constructing earthen mounds arranged into geometric patterns including lines, rings, crosses, and squares with diagonal lines.3Archaeological Research in Asia. OSL dates for the ancient geometric earthworks of Kazakhstan The variety of construction methods reflects the available materials and terrain. Desert cultures worked with surface stones and exposed sediment. Forest cultures dug into soil. Steppe cultures piled up earth.
Where Geoglyphs Are Found
Peru’s Nazca Pampa remains the densest concentration of geoglyphs anywhere on Earth, with figurative designs depicting animals, plants, and humanoid forms alongside vast geometric shapes. But the global distribution of geoglyphs is far broader than most people realize. The lower Colorado River region of Arizona and California holds its own tradition of ground figures, some depicting human and animal forms at monumental scale. Radiocarbon dating of these North American geoglyphs indicates they were made across a long span, from before roughly 900 B.C. to before about A.D. 1200.4Geoarchaeology. AMS 14C age constraints on geoglyphs in the lower colorado river region, arizona and california
The Amazonian earthworks of western Brazil were hidden for centuries beneath rainforest canopy and only came to light as modern deforestation exposed them. Research has shown that the landscape around these structures was not pristine wilderness before European contact. Bamboo forest dominated the region for at least 6,000 years, and the geoglyph builders made only small, temporary clearings for construction while actively managing the surrounding forest for millennia.5PubMed Central. Impact of pre-Columbian “geoglyph” builders on Amazonian forests The builders were sophisticated land managers, not slash-and-burn destroyers. The managed forest they shaped survived largely intact until the late twentieth century.
Kazakhstan’s geometric earthworks, identified from satellite imagery in the Turgai region and elsewhere, add another chapter. Optically stimulated luminescence dating places the earliest stages of these structures in the Early Iron Age, around 800 B.C.6Archaeological Research in Asia. OSL dates for the ancient geometric earthworks of Kazakhstan Their existence challenges older assumptions that steppe populations in this period were purely nomadic and lacked the social organization for monumental construction. The sheer effort required to arrange mounds into precise geometric shapes across open grassland implies planning, coordination, and a sustained investment of communal labor.
Beyond these well-studied regions, geoglyphs and geoglyph-like features have been identified in parts of the Middle East, Australia, the United Kingdom (chalk hill figures like the Uffington White Horse), and the American Southwest. Each tradition has its own construction logic, age, and cultural context, but they share a common thread: people felt compelled to mark the land at a scale that far exceeded the individual human body.
How Old Are They, and How Do We Know
Dating geoglyphs is notoriously difficult because the structures themselves are often made of rearranged rock or soil rather than organic materials that lend themselves to radiocarbon analysis. Researchers have had to get creative. In the lower Colorado River region, investigators used accelerator mass spectrometry radiocarbon dating on organic material trapped in rock varnish and weathering rinds on geoglyph stones, accounting for potential contamination from older organics already present in the coatings. Even so, the resulting dates are considered minimum-limiting ages, meaning the geoglyphs could be older than the measurements suggest.7Geoarchaeology. AMS 14C age constraints on geoglyphs in the lower colorado river region, arizona and california
For the Nazca region, optical dating of granitic stone surfaces has been applied. This technique measures the last time a stone surface was exposed to sunlight, which can indicate when it was flipped or repositioned during geoglyph construction. The method has been successfully applied to the Nazca lines around Palpa in southern Peru.8Archaeometry. OPTICAL DATING OF GRANITIC STONE SURFACES In Kazakhstan, a similar luminescence approach was used on the earthen mounds to establish the Early Iron Age date.9Archaeological Research in Asia. OSL dates for the ancient geometric earthworks of Kazakhstan
The difficulty of dating geoglyphs matters for more than academic timelines. It shapes debates about which cultures built them, whether different traditions influenced each other, and how long individual sites were actively maintained. A geoglyph that looks like a single creation event may actually represent centuries of modification if the dating resolution is too coarse to distinguish phases of construction.
Artificial Intelligence Is Transforming Discovery
Geoglyphs are, by definition, large, and many are difficult to see from the ground. Aerial photography has been the primary discovery tool since the 1920s, when early aviators first documented the Nazca Lines. Satellite imagery expanded the search area enormously in recent decades. But the real revolution has come from pairing high-resolution imagery with machine learning.
A 2023 study demonstrated a deep-learning pipeline for detecting previously unknown Nazca geoglyphs from aerial photographs. The system identified four new geoglyphs in the northern area of the Nazca Pampa, including a humanoid figure, a pair of legs, a fish, and a bird, all verified by on-site survey. The researchers reported that the AI approach identified new candidates approximately 21 times faster than visual inspection by a human analyst.10Journal of Archaeological Science. Accelerating the discovery of new Nasca geoglyphs using deep learning A key challenge was the extremely limited training data. Known geoglyphs vary in scale and design, so training a model to recognize all of them from a small number of confirmed examples required a custom pipeline rather than off-the-shelf object detection.
A larger-scale deployment followed. By applying an AI system across the entire Nazca region, researchers discovered 303 new figurative geoglyphs within just six months of fieldwork, nearly doubling the total number of known figurative geoglyphs.11PubMed Central. AI-accelerated Nazca survey nearly doubles the number of known figurative geoglyphs and sheds light on their purpose The AI proved especially effective at detecting smaller relief-type geoglyphs, which unlike the giant line-type figures are very hard to distinguish from the surrounding desert even in high-resolution photographs. These smaller figures had been drastically undercounted in previous surveys, and their discovery reshaped understanding of how the Nazca people used different types of geoglyphs.
The practical implication is that many geoglyph landscapes worldwide are probably underdocumented. If a single AI deployment could nearly double the known count at one of the most studied archaeological sites on Earth, the potential for new discoveries at less-studied sites is substantial.
What Were They For
Purpose is the question that generates the most public fascination and the most scholarly caution. For the Nazca Lines, proposed functions have included astronomical calendars, ritual pathways, water cult markers, and purely ceremonial or artistic expressions. The astronomical hypothesis, popularized in the mid-twentieth century, has largely fallen out of favor among specialists, as statistical analyses showed that the alignments between geoglyphs and celestial events are no better than chance. Water-related hypotheses remain more viable, with some researchers noting correlations between certain geoglyph types and subterranean water sources in the RÃo Grande de Nazca drainage.
The AI-driven discoveries have added a new layer. The finding that smaller, relief-type figurative geoglyphs were far more numerous than previously known has shifted the conversation. These smaller figures seem to cluster differently than the giant line-type designs, suggesting different social functions. The giant line geoglyphs, which can stretch hundreds of meters, were likely communal in nature and visible to large groups. The smaller relief-type figures, sometimes just a few meters across, may have been created by individuals or small groups for more personal or localized rituals.12PubMed Central. AI-accelerated Nazca survey nearly doubles the number of known figurative geoglyphs and sheds light on their purpose
For the Amazonian earthworks, the question of purpose is equally open. The ditched enclosures were clearly built with deliberate geometric precision, but no single function has been confirmed. Ceremonial gathering, astronomical observation, and territorial marking have all been proposed. The environmental evidence shows that construction involved only temporary forest clearings, which suggests these were not permanent settlements but rather sites visited periodically for specific purposes.13PubMed Central. Impact of pre-Columbian “geoglyph” builders on Amazonian forests Experimental archaeology is being used to evaluate construction techniques and workforce demands for these structures, which may eventually constrain theories about the social organization of their builders.14PubMed Central. Earthworks of the Amazon
The honest summary is that geoglyphs probably served multiple purposes, varying by culture, time period, and even within a single site. The impulse to find one unifying explanation is understandable but likely misguided. A Nazca line-type trapezoid and a small relief-type bird a few meters across were almost certainly not made for the same reason, even though they share a desert.
Threats to Geoglyphs
The same qualities that make geoglyphs remarkable also make them vulnerable. They are large, exposed, and often made of nothing more than rearranged surface material. A single vehicle driving across a desert geoglyph can destroy features that have survived for over a thousand years. In the Nazca region, remote sensing investigations have identified off-road vehicles and vandalism as primary threats to the geoglyphs’ fragile state of conservation.15Remote Sensing of Environment. Satellite and close range analysis for the surveillance and knowledge improvement of the Nasca geoglyphs Satellite monitoring combined with close-range analysis has become essential for tracking damage in real time.
Photogrammetric approaches using structure-from-motion techniques have been used to document specific instances of vehicle damage to Nazca-period geoglyphs, providing high-resolution 3D records that can serve both as evidence of destruction and as baselines for future monitoring.16Journal of Cultural Heritage. Combining Structure-from-Motion with high and intermediate resolution satellite images to document threats to archaeological heritage in arid environments The same approach can document damage from agricultural expansion, urban sprawl, and large-scale looting at archaeological sites in arid environments. In the Amazon, the primary threat is different: deforestation. Ironically, modern clearing is what revealed the geoglyphs in the first place, but continued forest removal exposes the earthworks to erosion, cattle trampling, and agricultural plowing that can level the ditched enclosures within a few years.
Tourism presents a double-edged situation. Visitor interest generates revenue that can fund conservation programs, but unregulated access causes physical damage. In Peru, the relationship between archaeological heritage and tourism has been described as a “constantly changing drama” involving local residents, the government, private tourism operators, foreign visitors, and indigenous communities, each with different stakes in how the sites are presented and protected.17American Anthropologist. Touring Ancient Times: The Present and Presented Past in Contemporary Peru The Nazca Lines became a UNESCO World Heritage site in 1994, which provides some international protection framework, but enforcement on the ground remains difficult across such a vast area.
Geoglyphs and the Land Art Tradition
Ancient geoglyphs did not exist in a cultural vacuum, and their influence extends into contemporary art and design. The twentieth-century Land Art movement, which emerged in the late 1960s, produced works that share a formal kinship with geoglyphs: large-scale earthen forms designed to interact with the landscape. Robert Smithson’s Spiral Jetty, Michael Heizer’s Double Negative, and James Turrell’s Roden Crater project all manipulate terrain at a scale reminiscent of prehistoric ground markings. The conceptual lineage has been explicitly traced from prehistoric geoglyphs and burial mounds through historical monuments to contemporary landscape interventions, including works like Maya Lin’s Vietnam Veterans Memorial and Martha Schwartz’s Jacobs Javitz Plaza.18IOP Publishing. Earthen Forms in the Landscape of Cities as Structures of Symbolic
The comparison is more than aesthetic. Both ancient geoglyph builders and modern Land Artists grappled with the same fundamental challenge: how to create something meaningful at a scale that exceeds the viewer’s immediate field of vision. The Nazca builders could not see their own creations in full. Neither can a visitor standing on Smithson’s Spiral Jetty. Both require the viewer to mentally reconstruct the whole from partial ground-level experience, or to gain altitude. The difference is that modern artists chose this disorientation deliberately, while for ancient builders, the relationship between ground-level experience and aerial visibility remains one of the enduring puzzles. Whether the Nazca figures were “meant” to be seen from above, or whether they were meaningful primarily as pathways walked on the ground, is still debated. The answer may be both, depending on the type and size of the figure.
Common Misconceptions
The most persistent popular myth about geoglyphs is that they required aerial viewing technology to create and therefore imply lost advanced civilizations or extraterrestrial assistance. This idea, popularized in the 1960s and 1970s, has no support in the archaeological record. Geoglyphs can be and have been replicated experimentally using stakes, cords, and simple surveying techniques available to any organized group of people. The figures are geometrically impressive but not geometrically impossible. Straight lines can be extended over long distances with minimal tools, and curved figures can be laid out using scaled-up versions of small designs.
A second misconception is that the Nazca Lines are unique. They are the most famous and arguably the most elaborate, but as the evidence from Brazil, Kazakhstan, Arizona, and elsewhere demonstrates, the impulse to create large ground markings was independently invented by multiple cultures on multiple continents. The Nazca tradition is exceptional in its density and variety, not in its existence.
A third misconception concerns the Amazonian geoglyphs specifically. Early media coverage often framed them as evidence that the Amazon rainforest had been cleared for agriculture on a massive scale before European contact. The actual research tells a more nuanced story. The geoglyph builders managed their forest landscape actively but did not engage in widespread deforestation. Construction involved only small, temporary clearings, and the surrounding forest was shaped by human management but remained largely intact as forest.19PubMed Central. Impact of pre-Columbian “geoglyph” builders on Amazonian forests The distinction matters: these were forest people who built monumental structures within a forested landscape, not people who destroyed the forest to do so.
Geoglyphs We Have Not Found Yet
The speed at which AI is uncovering new geoglyphs at Nazca, one of the most intensively studied archaeological landscapes in the world, raises an obvious question about everywhere else. If 303 previously unknown figurative designs were hiding in plain sight at a UNESCO World Heritage site that has been surveyed by archaeologists for nearly a century, how many geoglyphs remain undiscovered in less-studied regions?20PubMed Central. AI-accelerated Nazca survey nearly doubles the number of known figurative geoglyphs and sheds light on their purpose
The Amazonian earthworks are a case in point. The 450-plus enclosures documented so far occupy a single Brazilian state, and only the portions exposed by modern deforestation have been surveyed. Comparable structures may exist under intact canopy across a much larger area. Lidar technology, which can penetrate forest cover to map ground topography, has already revolutionized the archaeology of tropical regions in Central America, where it revealed massive Maya urban infrastructure beneath jungle. Similar systematic lidar campaigns over the western Amazon could dramatically expand the known extent of geoglyph construction in that region.
Kazakhstan’s steppe earthworks are in a similar position. The initial discoveries came from Google Earth browsing, and systematic survey using higher-resolution imagery and AI detection has barely begun. The earliest dated structures go back to around 800 B.C., but the full geographic and temporal range of the tradition remains unmapped.21Archaeological Research in Asia. OSL dates for the ancient geometric earthworks of Kazakhstan Saudi Arabia, Jordan, and other parts of the Middle East also contain vast numbers of large-scale stone structures visible from the air, many of which remain formally undocumented and undated. The coming decade of satellite archaeology, powered by increasingly capable AI and ever-higher-resolution commercial satellite imagery, is likely to rewrite the global map of monumental ground construction in ways that make even the Nazca discoveries look like a warm-up.