Hidden in plain sight: Engineering marvels of the Ancestral Puebloans

A version of this article appeared in Preservation magazine in July/August 2003.

Is or isn’t it an ancient shovel?
Archaeologist Kurt Anschuetz navigated his pickup slowly along the uneven bottom of the arroyo. Skirting hillocks and boulders, we made our way from Tesuque Pueblo into the high desert north of Santa Fe. From the front passenger seat, Louie Hena, a Tesuque farmer and tribal council member, shown near left with Anschuetz, scanned the sandy 60-foot walls. He was looking for the spot where he had seen what seemed to be the remains of small, gravel-mulched, cobble-edged fields (usually called grid gardens or gridded plots) built by his ancestors. The newly rediscovered type of early Pueblo agriculture is redefining the concept of irrigation and providing powerful new legal evidence for communities, like Tesuque, that are engaged in water litigation.

However, on that day in August 2001, Hena was concerned about PNM, New Mexico’s utility company. It had long been developing plans to march a power line through the area, which was part of Tesuque’s reservation. The utility’s archaeological studies—undertaken in 1985 as required under federal lawhad found no evidence of the old plots that Hena had recently spotted.

But Hena knew that most archaeologists, accustomed to studying dwellings, wouldn’t recognize the little-understood fields. He hoped that Anschuetz, an expert on them, would agree that artifacts of Tesuque’s heritage were in harm’s way.

Hena had met Anschuetz, who directs the Rio Grande Foundation for Communities and Cultural Landscapes, a Santa Fe nonprofit that helps groups preserve their traditional lifeways, at a 1994 environmental conference at Taos Pueblo. The two men discovered a mutual fascination with the early agriculture of northern New Mexico and undertook a cross-cultural collaboration. Combining the analytical tools of the scholar with the practical knowledge of the Indian farmer, they have co-published papers and given presentations to groups including Native communities, gardening students, and lawyers.

As the ancestors of today’s Pueblo people moved south from the Four Corners area (the point where what are now Colorado, Utah, New Mexico, and Arizona meet) after 1250, they expanded on the agricultural techniques that they’d used up northmainly contour terraces, reservoirs, ditches and check dams. In the process, they created a dynamic system of multiple technologies that they scattered across the land.

Hena tries what seems to be an old planting tool
This practice, called land-extensive agriculture, provides protection against environmental challenges (such as long-term drought or localized storms) and human demands (such as population growth, either gradual or sudden, as when Cochiti Pueblo took in refugees during the 1680 Pueblo Revolt against the Spanish).

Gravel-mulched, rock-bordered fields were one of the new techniques the ancestral Puebloans devised upon arriving in what is now north-central New Mexico. They eventually constructed about 10,000 acres’ worth of the rectilinear plots in the valleys of the Rio Grande and its tributaries; most of the fields were installed between 1300 and 1500. Each grid garden is, on average, about nine feet by twelve feet, and is bordered by cobbles that are approximately seven inches high and ten inches long, laid end-to-end.

The farmers covered the topsoil within each rectangle with gravel mulch, which was designed to trap rainfall, melt snow, and prevent evaporation. The mulch also encouraged moisture to soak into the ground, where it seeped downslope past the roots of crops in one hillside field after another. By doing this, they made sure that little evaporated or ran off, as rain or snowmelt ordinarily would—essential in this region of meagre precipitation.

In the rich soil, the farmers grew cotton for clothes, as well as corn, beans, squash, perennial herbs, and other foodstuffs. They bred special domesticated plants, such as corn with an especially long mesocotyl (the first shoot that breaks through to the surface after germination); this variety can be planted at depths of up to 16 inches to take advantage of underground moisture.

In and around the beds, the early Puebloans managed other, non-domesticated plants (contemporary Indian farmers don’t like to call them “wild,” since they were encouraged to grow, not merely collected randomly). This huge array of affiliated plants—including purslane, lamb’s quarters, amaranth, yucca, and much moreprovided everything from food and medicine to fiber and soap. Prickly pear cactus, which seeds itself in cracks in rocks, sprang up between the cobbles, providing edible pads and flowers as well as a spiky fence that kept out small predators. Remnants of these plant populations can still be seen in some plots.

Clusters of grid gardens range in size from a few isolated plots to hundreds of contiguous ones. In aerial photographs of the region, the groupings look like nets cast over the hilly land bordering the rivers. They have caught the eye of pilots as far back as Charles Lindbergh, who photographed them while flying over Abiquiu Mesa in 1920s. Their ground-hugging patterns can be easier to see from the air, I learned in a conversation with pilot Lee Baker, whose husband, archaeologist Tom Baker, photographs old sites from her plane. “In some areas,” she said, “where they are very subtle, you can see them while you’re flying. Then, if you parachuted right down into them, you probably wouldn’t be able to see them at all.”

Initially, I couldn’t pick out the gridded plots at all when Clayton Brascoupé showed me the ones at Poshu-ouinge, a 13th-to-18th-century pueblo in the Santa Fe National Forest. Brascoupé is the Mohawk-Algonquin director of the Traditional Native American Farmers Association, an intertribal community-outreach organization in Santa Fe. It was my first visit to the Southwest and, frankly, the area looked to me like an undifferentiated expanse of rocks, sand, and the occasional shrubby tree.

Then, as Brascoupé pointed example after example, the subtle rectangular outlines snapped into focus. I was to learn that day, and in subsequent visits to other plots, that so much of what made them work so well was just at, or even below, the surface. Their efficacy has profound implications for modern land use; they are also redefining the concept of irrigation, which affords powerful support for present-day Pueblo water claims.

The remains of grid gardens seen from the air
The grid gardens were ignored or misunderstood by scholars for much of the 20th century. In 1880, guides from Santa Clara Pueblo identified the structures as agricultural when they led Swiss-American explorer and archaeologist Adolph Bandelier to one of their ancestral pueblos. Later researchers rejected this description as oral history, therefore unreliable, and devised alternate explanations that seem fanciful in retrospect. They postulated that the rock enclosures were plans for homes that were never built or the remains of pre-ceramic pueblos. Why anyone would have planned such immense dwellings, or how they could have constructed them, remained as much a mystery as what they were to begin with.

During the late 1970s, David Bugé, Katherine Fiero, Richard Lang, and other prominent archaeologists took a second look at hypotheses about the rock traceries and reintroduced the idea that they had an agricultural purpose. Over the next two decades, important studies and doctoral dissertations by Anschuetz, Timothy Maxwell, James Moore, John Ware, Steven Dominguez, and others confirmed this.

Roads, buildings, and other facilities have obliterated some of the grid gardens; I saw cattle lumbering through others. All-terrain vehicles also cause tremendous havoc; ATVs not only rip up the ecologically fragile desert surface, they also enable their owners to bounce through hitherto inaccessible places. “Distance from roads has always been the best protection for old sites,” says archaeologist and hydrologist Dominguez. “Now, with increased access, so much is in danger.”

The remaining fields sit on land with an unrelated patchwork of ownership: individuals, municipalities, Indian reservations, the State of New Mexico, the U.S. National Forest Service, the Bureau of Land Management, and the Archaeological Conservancy, among others. Some of these entities are determined to protect the gardens and their associated dwellings and field houses through legislation forbidding vandalism and theft, or via locked gates. Others may not know the structures exist.“They are protected under preservation law, but it’s such a vast landscape, and the gardens cover thousands of acres of it. That’s the tough part,” says J. Michael Bremer, Forest Archaeologist of the Santa Fe National Forest. “Even at our fenced site at Poshu-ouinge, cows and elk sometimes break in.”

As we lurched along the arroyo, Hena and Anschuetz filled in some details. “My ancestors treated the land as a sponge, encouraging water to soak into the ground,” Hena explained. In contrast, he said, the modern irrigation systems you may be more familiar with flush water over the earth’s surface in concrete-lined canals. “It looks efficient, but a lot is lost to evaporation that ends up as rain somewhere else,” said Anschuetz.

Hena added, “You aren’t feeding the roots of beneficial plants or recharging wells along the way. In recent decades, the Bureau of Indian Affairs has done us, and other Pueblos, the supposed favor of lining our irrigation ditches with concrete. Here at Tesuque, the wild plum trees along the ditches died as a result, and we lost a food source.” Also important, water passing through a concrete-lined ditch doesn’t recharge the aquifers, a critical failing in the arid West, where the great underground water repositories are shrinking nowadaysa sword of Damocles hanging over all of us.

Under cultivation until the mid-1700s, many of the now-unused grid gardens are still doing what they were designed to dohold moisture and soil and promote growtheven though no farmer has turned up to maintain them in 250 years. “Often, you can spot them because they’ve got grass growing in them,” Anschuetz pointed out.

For all their subtlety, they’re remarkably rugged. During the early 20th century, a dirt road was built through the plots near Sapawe, a 2,000-room pueblo on the banks of the Rito Colorado that was occupied during the 1500s and 1600s. After all these years, and periodic passes by road scrapers, the cobbles haven’t budged.

By siting this particular type of field on hills and mesa tops, the farmers of old avoided the cold air that settled in the flood plains of major rivers and shortened the growing season in the valleys. On the other hand, higher-altitude plantings couldn’t be irrigated with water diverted from the streams, as those in valleys could have been; manipulating precipitation was therefore critical to the grid gardens’ success.

Deciding where to site their plots was not the farmers’ only consideration. They also tailored stone hoes, shovels, axes, and digging sticks to fit the requirements of different crops and soil types. The heavy tool heads can still be found in the beds; their owners likely stashed the items where they needed them and carried handles that could be lashed on. At the end of the growing season, they left a cover of stubble behind to shelter birds and small animals and to entice browsing deer, which contributed to the community’s meat supply.

Demonstration garden at Pojoaque Pueblo
“When the Spanish got here in the 1500s, they described this land as a Garden of Eden. Now it’s dry,” Hena said defiantly as we jolted down the arroyo. “What’s different? We Indian people are not out there, managing the land. Nowadays, there’s a lot of erosion, and a lot of topsoil is lost. You can see it in the turbidity of the water when we have sudden rains and flooding.

“In the old days, with our ancestors managing the watersheds from the top down, the water soaked into the ground, slowed down, and continued downhill and out onto the plains without taking the topsoil with it. In fact, the stuctures we Pueblo people placed on the hillsides captured topsoil, increasing it.”

For their sophistication, as well as their extent, the grid gardens are as significant as the aqueducts and other engineering feats of Rome, according to Dominguez. But, whereas the aqueducts are impossible to miss, these fieldworks are nuanced modifications of the landscape that are nearly hidden in plain sight.

To bolster his claim, Dominguez subjected the plots to rigorous hydrological analyses. Digging into the gardens with a mason’s trowel; then, using sieves with graduated mesh sizes to separate rock from soil, he gathered data from a promontory called La Mesita, in the Rio Santa Cruz Valley, northeast of Santa Fe. Upon analyzing the numbers, he discovered that the fields operated with diamond-cutter accuracy. The farmers used optimum stone sizes for their gravel mulch, which increases water absorption, cuts evaporation and runoff, and checks erosion. “Fifty millimeters is the upper limit for the size of stones that can be used effectively,” Dominguez explained; in the fields he studied, most stones were between two and fifty millimeters. Further, he noted, the entire layer should be at least three centimeters thick. At La Mesita, the rock coverings of north-facing plots averaged just that; in south-facing beds, where plants had to survive additional hours of dessicating sunlight, the thickness was plumped up to an average of five centimeters.

Snowmelt was as important as rain in a region that counts the winter months among the wetter ones. “I was out in the middle of a snowstorm when I realized how effectively the gravel mulch melts snow, building up moisture for spring planting,” he recounted. “The rocks hold heat, so the garden beds were patches of bare gravel, while the snow was piling up around them.”

The cobble borders also helped collect winter precipitation. As a rule, Dominguez says, hydrologists find that the most efficient snow fencesincluding low ones like thesehave gaps no larger than 25 centimeters, with all the openings adding up to 40 to 60 percent of the surface area. Measuring the barriers at La Mesita, he calculated that they conformed to these exact requirements.

Then Dominguez checked topographical maps to see where the structures were placed on the landscape. Again, the farmers were spot on: The fences were at ideal angles to the prevailing winds and at optimum spots on the hillside slopes to gather snow.

And, the gardens’ builders had accurately calibrated the proportion of fence height to distance between barriers; the snow would have just filled one plot with a drift before hitting the next row of stones and forming another billow. The dimensions of the beds deviated from the nine-by-twelve-foot norm in spots where changes in a hill’s incline would have caused the wind speed to increase or decrease, thereby altering the lengths of the drifts. “This ability to take advantage of wind speed and direction is why you see a lot of grid gardens on hilltops--and why you see them from the air,” Dominguez says. “The only kind of moisture that moves upslope is blowing snow.”

The precision with which the fields were constructed, he added, gave the farmers tremendous flexibility, allowing them to deal with changes in terrain, to respond to short-term changes in weather, and to survive long-term environmental and population shifts.

To achieve this exactitude, the old-timers put their faith in observation itself, rather than in instruments of observation. The ability to look carefully has so atrophied for most modern people, they may have a hard time believing the ancients were so acute, says Dominguez: “We city dwellers have no clue. For me, the book learning was just part of being able to do this work. The other part was getting out there, seeing the rain falling or the snow blowing. The fields’ builders were walking the land, observing spring growth, looking at plants responding to different conditions, watching how everything interacted. And many generations of meticulous observers preceded them. The farmer of todaythe farmer of agribusinessis a technician. He follows instructions. The expertise resides not in him, but in John Deere or Monsanto.”

The ancestral farmers even figured out that you have to deliver air as well as water to the plants’ roots, says Anschuetz. In some locales, he and Hena found that the old Pueblo irrigation ditches spilled their water through openings that were partially blocked with rocks, creating turbulence and aerating the water so that it was rich with oxygen.

“The symbology of that facet of the planting is so incredible,” says Tessie Naranjo, a sociologist from Santa Clara Pueblo who has written on Pueblo agriculture and pottery. “We have a supernatural being called the water serpent. You see him in decorations on our pots. He is the aerator of the ground and makes it breathe so the crops can come up.”

Efficacy may have been important to the early Pueblo farmers, but they also appear to have reveled in some of the most dramatic scenery in North America. Whoever built the plots on the rim of La Bajada Mesaa 500-foot escarpment overlooking a 50-mile valley ringed by precipitous peakshad a well-developed sense of theater. However, that spot is also a great place to plant. “Right there at the very edge, the slope of the mesa top flattens out, so it receives the slowest moving water, delivered continuously to the plants,” Anschuetz explains.

 “I have looked at many of the old sites, and at every one, I marvelled at the choice of location,” says Naranjo. “There’s an instant apprehension of the beautiful and the practical. That describes the Pueblo mind.”

Cochiti offers a contemporary example of this notion: Water passing through unlined irrigation ditches has given rise to a grove of trees near fields cultivated by elder farmers Joseph Benado and Gabriel Trujillo. In the thicket, they have placed a bench, where they can periodically rest in the cool, damp air and admire the scene framed by the boughs: tasseled corn rustling its fronds over bright chilies, cheeping birds, distant mountains limning the boundary between earth and sky. However, because the little stand of trees makes a long day in the brutal desert heat possible for the farmers, it is as useful as it is lovely. “It’s beauty and function all rolled into one,” says Naranjo.

“I think this is the place,” Hena told Anschuetz, who stopped the pickup. Hena got out and sprinted up the nearly vertical walls. He walked along the top of the cliff, as Anschuetz and I followed along in the bottom of the arroyo. “Alluvial soil,” remarked the archaeologist, indicating the exposed earth walls. “The Rio Grande is a rift valley. When it collapsed millions of years ago, it left a deep layer of a combination of sand and loam that had washed down from what is now Colorado. It’s great for farmingif you can get water to it.”

Hena found what he was looking for and called out. Anschuetz and I climbed up to join him. Juniper and piñon trees dotted the hilltop. Across the Rio Grande Valley, the crags of the Sangre de Cristos Mountains hulked on the eastern horizon, and cumulus clouds floated in a bright blue sky.

“OK, let’s see what you see,” Hena challenged Anschuetz, who suddenly crouched by one of several low four-foot-wide mounds of broken stones. “Firecracked rock,” Anschuetz explained for my benefit. “Here are the distinctive right-angle breaks and the orange markings-iron oxidized by heat. These pits might have been places to roast corn. Now, because of erosion, they look like mounds.”

For several hours, the two men worked their way over the hill, finding fire pits; garden beds; terraced gardens; a metate, or flat stone for grinding corn into meal; and a flake, or sliver of rock, knocked off a piece of quartzite that one of Hena’s distant grandfathers had fashioned into a tool. Each discovery provoked a spirited debate. “Louie will be challenging me every step of the way now,” joked Anschuetz.

As an archaeologist, the Anschuetz looked for material evidence of human interaction with the artifacts, such as concoidal fractures on the edges of tools (“like the breaks you get when a beebee goes through glass,” he explained) and alignments of rocks that could not have been caused by geological processes. Meanwhile, Hena sought living proof of his ancestors’ activities. He would note that a bit of land was greener than its surroundings and postulate that it was a garden bed that was still collecting topsoil and water; or he would notice that a series of trees was thriving in what seemed to be a row of cobble-rimmed enclosures, perhaps because of better growing conditions there.

At one point, Hena picked up a stone that looked like an old hand hoe, testing its heft in his hand, demonstrating how easily it cut into the soil. “Much better than a modern one,” he said. “I’ve done a lot of fieldwork, and these rock tools are good. It’s near here that I found that old double-handed shovel. I use it now, and it goes down easy.”

“I don’t see a working edge,” retorted the ordinarily soft-spoken Anschuetz, as he turned the palm-size rock over in his hands. He then defended his position to me: “I take a conservative approach. That rock may have been used as a tool. I can see how beautifully it works when Louie uses it, and one of his ancestors may also have found this to be true. But I need to see clear indications of use on its surface. When Louie points out places that would be good to plant or tools that feel right in the hand, I listen. Then I look for what lets me define them as such and nearby pottery shards that date them. Archaeologists base their version of the story on the most redundant, unquestionable evidence.” He asserts that therefore the archaeologist therefore offers just a part of the whole picture: “If it’s not material, we can’t see it. We may miss things, like fields that were bordered by brush or worked with wooden tools. But that doesn’t mean they’re not there.” The traces of some ancient farming techniques may have melted awaylike the old mud-brick pueblosback into the earth’s surface.

After Hena and Anschuetz finished wrangling over an artifact, Hena deftly fitted it back into the cavity created when he had removed itpatting the dirt around the chunk of stone as tenderly as if he were transplanting a seedling. Finally, Anschuetz conceded the larger point: “I’m seeing arrays of stone that couldn’t have been formed by geological processes. We’re getting close to where I could say that these are old fields, that identifying them as such would hold up in court.”

In fact, these gardens, or others like them, may figure in legal cases. Many New Mexico communities are engaged in long-standing disputes over water, an increasingly precious resource in the arid West. Though the Pueblos have priority claims, because they were the first to irrigate in the region, amounts have been a long-standing point of contention. The allocations have been based on the amount of water that was diverted from rivers to low-lying fields via canals. However, the hilltop grid gardens indicate that early Pueblo farmers captured and diverted much more, using sophisticated techiques.

“We have aboriginal water rights, but increasingly, the courts want more detailed information. The old gardens will be useful in providing it,” says Herman Agoyo, tribal council member and former governor of San Juan Pueblo. “Farming has been neglected in terms of land and water rights.”

The old fieldworks are more than legal weapons, though. “Other applications of information about the gardens are also coming into being,” says Agoyo. “Kurt and Louie have contributed to our education about the activities of our ancestors and to our understanding that ecology is about interconnectedness. It’s inspiring to see that our forebears were so knowledgeable, and that what they were doing with the land and environment shaped our lives today, and all of the connections throughout the universe.”

Hena and Brascoupé have put some of the old techniques to work in their fields. Hena uses traditional principles when restoring eroded land. “Originally, I would start at the low end of an area and work up, putting in check dams and gabions,” he says. “Then, I noticed that my people would start at the top and work down. Using that approach, I’ve seen how much more topsoil the structures capture and how much growth arises to hold that soil.”

He also places large cobbles in his household garden, where they act as heat sinks, protecting the plants by taking up warmth during the day and releasing it at nighta technique he saw in the old fields. I touched the surface of one of the rocks at mid-day; it was burning hot. Hena pulled it aside; the soil beneath was cool and wet.

Brascoupé found that the old-time tools outperform modern ones in desert soil. He uses a digging stick instead of a tractor when planting his fields. A machine’s blades would churn the surface, he says, breaking up the structure of the soil, drying it out, providing footholds for weeds, and oxidizing the nutrients instead of letting the plants take them up as they grew. He also notes that the biodiversity around the old plots played two important roles: It ensured gene swapping between the domesticated plants and their non-domesticated relatives, and the variety of blossoms attracted an array of pollinators—necessary for a healthy garden.

Throughout the Pueblos, people worry that agriculture is disappearing as a way of life for them. “What does a harvest festival mean if we are no longer harvesting?” one person asked. Communities are experimenting with ways to reverse the trend—setting up agricultural cooperatives, children’s gardens, and the like. Brascoupé’s Traditional Native American Farmers Association works with many communities; the group also offers an annual gardening workshop that attracts mainly young Native people.

The emphasis on youth is pervasive and is entwined with language-preservation initiatives. “Without language, they have no connection to the land,” Agoyo says. The precipitous loss of the world’s languagesas large regional ones like English, Spanish, Mandarin, and Swahili swamp smaller oneshas triggered awareness of what is lost when a tongue is silenced. Knowledge, both practical and poetic, disappears forever.

Benado, of Cochiti, explained some of the information that the Keres language holds. Speaking in the harmonious, breath-infused tones of the language of the southern Pueblos, he explained through a translator that for his people plant-rearing is akin to child-rearing and that the two activities have a comparable vocabulary. He then expanded on the linguistic complexities of Pueblo farming by describing the life cycle of corn and the different names the plant has at every stage from planting to harvest time. Shifting into English, he added, “As a farmer, you enjoy what you do so much. When I look at my family’s table, filled with what I have grown, I feel such joy at having provided for them. Farming makes you a better person, because you are always looking forward to next year.”

I described what I had heard in Benado’s voice—its musicality and breathiness when he spoke in Keres—to Naranjo. “When older Pueblo people talk about corn, they’re reverential,” she explained. “When corn came to us, we danced for the bounty. When wheat came to usfrom the Spanishwe grew it, but never danced for it. We never assigned sacredness to it. Corn is irreplaceable. When Mr. Benado talks about corn, he goes to that sacred place.

“The breath in his voice expressed our sense of ourselves as being a part of a universe in which everythingincluding rocks, trees, and cloudshas breath. We take in their breath when we need to borrow their power. When my father, who was great hunter, brought down two or three deer, we’d have a deer dance, because the deer gave up their breath for our survival.”

Over the course of the afternoon, the clouds had darkened, and thunder had begun to rumble. Lightning plunged into the Sangre de Cristos Mountains across the Rio Grande Valley, as the archaeologist and the farmer took a break from their survey of the hilltop. Silhouetted against the storm and speaking urgently, Hena explained the gardens were more than a repository of historical relics, more than a reminder of his tribe’s lost past. The sky was the vault of their cathedral, he said, the earth their altar. “Wouldn’t you call this place sacred?” he demanded.

Update: Ultimately, PNM decided to send the line up a nearby highway, sparing the ancient gardens.

c. Stephanie Woodard; photographs by Stephanie Woodard.