Archeology

UNEARTHING A CULTURE

The little band of archeologists stood atop the Southwest's most baffling missing-persons case and strained to understand.

At their feet lay an enigmatic mound of dirt and stone that once formed the hub of a thriving civilization on the banks of the Salt River as it meandered through the Tonto Basin just 80 miles from present-day Phoenix. Schoolhouse Mound, a complex of rooms and granaries built atop a 10-foot-high dirt platform 600 years ago, dominated the surrounding landscape and 2,000 acres of laboriously irrigated corn and bean fields.

Arizona State University archeologist Glen Rice, the senior principal investigator who directs what has become the biggest archeological dig in the United States, peered down the boulder-strewn, saguaro-studded slopes of the secluded river valley that once cradled the Salado civilization. The nearly $10 million project is funded by the United States Bureau of Reclamation. In his mind's eye, Rice visualized the chain of platform mounds his crews had mapped along the old river course at three-to five-mile intervals, each marking a concentration of wealth and power in a valley supporting perhaps 10,000 people menaced on every side by desert and famine.

The Salado Indians occupied the area for 300 years, tilling thousands of acres of irrigated farmland, making pots of wonderful beauty, establishing trade networks that stretched from California to New Mexico, and thriving despite repeated cycles of drought. Then they vanished, along with most other major Southwestern Indian cultures, from the Hohokam who abandoned hun-dreds of miles of irrigation

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Canals near present-day Phoenix, to the Anasazi who deserted their exquisitely balanced cliff dwellings in places such as Chaco Canyon and Mesa Verde. What happened? Where did they go? Why did these ancient desert societies collapse after a millennium of steady growth and ingenious adaptation? "This is a natural laboratory," said Scott Wood, the Tonto National Forest archeologist. "For many, many years it was hard to get people interested in the Tonto Basin at all. All of a sudden, it's the site of the largest archeological project in the country. It's the most ambitious attempt to look at all aspects of a society over a long period of time that has ever been done in North America.

On this particular morning, Rice, Wood, and field archeologist David Jacobs glimpsed a clue to the structure of the whole society in the spacing of the mounds all down the valley. The platform mounds must have anchored the intricate system of irrigation canals that diverted water from the river to the fields and marked the emergence of a ruling elite whose demands drove the society - and perhaps doomed it.

"Sometimes, there's an amazingly brief moment of understanding," Rice said. "Scott [Wood] has an incredible firsthand knowledge of the distribution of sites. He felt that the late platform mounds were arranged in a way that showed that one of their important functions was to control irrigation."

That's the kind of insight the unusual, eight-year project was designed to foster. Archeologists also hope they'll gather new clues to the vexing mystery of the disappearing civilization. The United States Bureau of Reclamation has funded the work in connection with a $347 million project to raise the level of Roosevelt Dam, which ultimately could inundate vital clues to the mystery.

Ironically, earlier archeological work spurred the dam project. Analysis of tree rings on wood samples pulled out of Indian ruins in the area showed that the dam might one day have to handle flood flows fourtimes greater than its designers anticipated.

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The ASU teams are working on a $6.8 million, eight-year contract to excavate and interpret the platform mounds. Tucson-based Statistical Research has a two-year, $400,000 contract to study the "rural" settlements on the flanks of the valley, which harvested agave, prickly pear, and saguaro fruit. In addition, Desert Archaeology has a five-year, $2 million contract to reconstruct the growth of village life in the basin.

It will take years of analysis before the scattered teams come up with a single clear picture.

But already the work has sketched the outlines of a thriving society in an unforgiving environment, a society that may have been undone by its own success.

The key to the riddle may lie in understanding two key sites. One is the Pillar Mound, an ancient temple built to pay homage to the sun. The other is Schoolhouse Mound, a giant granary and power center that marked the emergence of a society that might have finally overtaxed its environment.

The Pillar site is the oldest of five platform mounds the ASU crews have studied, dating back more than 700 years. Its construction marks the development of the distinctly Salado culture, which appears to have been influenced by both the Hohokam in the Phoenix area and the Mogollon cultures in the nearby Mogollon Rim country.

The Pillar site represents one of the most striking finds in Southwestern

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It was at this site (LEFT) that archeologist Dr. David Jacobs happened to observe the sun's rays lining up with the roof-support pillars and doorways, inspiring the name Pillar Mound, and leading to speculation about the structure's purpose as a temple or gathering place.

(BELOW) Near Bass Point Mound, scientists discovered a sun petroglyph, one of many “talking stones” in the area.

archeology in part because it was, practically speaking, useless.

The mound started as a structure of mud and rounded river cobbles enclosing two oversize rooms that were dominated by twin sets of pillars in the middle. At some point, the Salado filled in the original rooms with dirt and stone and built an almost identical complex on top of the resulting mound. They also added several groundlevel rooms that could be reached only through a long, narrow passageway.

The enigmatic pillars in the middle of the rooms turned out to be braces for roof beams that supported extra-high ceilings. But the scientists soon came across another mystery: they found almost no household debris such as cooking hearths or bits of pottery. Apparently, no one actually lived in these giant rooms, which likely means the Pillar site was a temple or gathering place.

But the most remarkable discovery about the Pillar site grew from a chance observation by field director David Jacobs one chilly December morning a few weeks after the winter solstice, the shortest day of the year. Jacobs noticed that the rising solstice sun seemed to line up nicely with the pillars and doorways.

“I walked to the back of the room and turned around to look out the door and noticed that was exactly where the sun had risen on solstice. I thought, that's odd. I walked out of the room and into the next room and back to the corre-sponding corner, and it lined up to the same point.

“It was at that moment it clicked. It's not so much the 'ah-ha' moment. It's more like, you jerk, why didn't you see it a lot earlier?” Subsequent measurements confirmed that, on the shortest and longest days of the year, the sun streamed through the doorways, illuminated the pillars, and cast a thin dagger of light across the floor and up the back wall. The Salado must have marked these days with great ceremony.

But a very different picture emerged from the next major platform mound excavated: Schoolhouse. This giant, L-shaped mound reached its peak activity about 200 years after the Pillar site was abandoned. Pillar probably withered after a side-canyon flood destroyed the nearby irrigation works, and compelled the descendants of its builders to move on down valley toward Schoolhouse. They took with them a much more complex, wealthy, and ultimately vulnerable society than the loose alliance of clans that had built their temple to the sun at Pillar.

For one thing, Schoolhouse was much larger, a bustling, 300-yard-long complex of 115 rooms that served as an economic center. Like the Pillar site, Schoolhouse evolved over time. Year by year, its builders added rooms, developing a complicated, jumbled floor plan like cells dividing in a petri dish.

Then, in an impressive display of mass labor, they filled in most of those ground-level rooms with rocks, dirt, and debris and built a whole new complex of rooms on top just as they had done at the Pillar site. But this was a whole village with rooms for perhaps 200 people.

The biggest surprise at Schoolhouse was the discovery of rooms filled with giant pots and built-in granaries, made of woven branches and plastered with mud, that held great quantities of surplus food.

“We found these incredible storage rooms, one after the other, that have all this evidence of huge storage capacity: large vessels, granaries, baskets, just amazing,” said Owen Lindauer, the archeologist who heads the ASU field crew that excavated Schoolhouse. “These granaries have made an incredible contribution to understanding the economic aspects of this community.”

A CULTURE

The Salt River (ABOVE) enters the Tonto Basin at the east end of Roosevelt Lake. The river is flanked by rich soil-covered basins and mesas that provided an ideal environment for the Salado. (OPPOSITE PAGE, ABOVE) Viewed from Tonto Basin along Reno Creek, water cascades over a cliff in the Mazatzal Mountains. (OPPOSITE PAGE, BELOW, LEFT) Workers at the dig carefully sift dirt through wire-mesh screens to find small artifacts. (OPPOSITE PAGE, BELOW, RIGHT) Archeologist James Marino collects samples from a Salado hearth at Schoolhouse for archeomagnetic dating.

An exquisitely decorated Tularosa black-on-white pottery canteen (ABOVE) placed in fast-flowing Sycamore Creek by the photographer to create an interesting background, was originally acquired by the Salado in trade. (OPPOSITE PAGE, ABOVE) During the hot summers, the Salado Indians were drawn to any water they could find, such as the shallow ponds of Tonto Creek. It was the water flowing from the Salt River that made possible the development of the Salado culture. (OPPOSITE PAGE, BELOW) At Schoolhouse, Dr. Owen Lindauer, left, and Lynn Simon painstakingly clean a wood post before sending it to a laboratory for analysis and dating.

The majestic Four Peaks (ABOVE) look down upon the land of the Salado. Perhaps these crags were sacred, visited only by priests who brought prayer offerings or ventured to its cliffs to gather eagle feathers for ceremonies.

(OPPOSITE PAGE, ABOVE) Spring wildflowers carpet the Tonto Basin below Roosevelt Lake and the looming Sierra Anchas.

(OPPOSITE PAGE, BELOW, LEFT) Archeologist Kathy Hensler admires a Pinedale black-on-red bowl that dates from A.D. 1300. This pottery probably was made in eastern Arizona and traded to an inhabitant of the Tonto Basin.

(OPPOSITE PAGE, BELOW, RIGHT) At the field laboratory, Paula Pyatt uses a weak acid solution to clean a section of a Tonto polychrome pottery jar.

UNEARTHING A CULTURE

Continued from page 8 Lindauer estimates that the storage rooms of Schoolhouse could have held enough corn, beans, and other food to carry the people living on the mound through years of crop failures. Schoolhouse also marked the appearance of an elite group that could control huge surpluses and command the mass labor, the evidence of evolving social complexity Rice had hoped to find. Rice, 43, has devoted the last decade to understanding the enigmatic Salado, who offer a small, graspable metaphor for the fate of Indian cultures throughout the Southwest.

A mild-mannered archeologist with a boyish shock of hair swept to the side, a neatly trimmed beard, and an air of dogged obsession, Rice was convinced that the Tonto Basin can yield clues that can be applied to the almost simultaneous decline of other Southwestern cultures. That includes the Hohokam from whom the Salado probably got the idea for platform mounds. Roughly similar complexes have been found in the Phoenix area in which the mounds appar-ently evolved from large, elevated areas where the Hohokam staged dances with neighboring groups. Eventually, the Hohokam built multilevel complexes atop these elevated areas. Perhaps Salado traders brought back stories of the Hohokam mounds that inspired the Salado honchos to order their own version to prove they were just as grand as the Hohokam elite.

In fact, a more detailed picture of life among the Hohokam also has emerged recently as a result of a huge archeological dig inspired by the aptly named Hohokam Freeway, which cuts straight through a prime Pueblo Grande archeological site. That project has revealed how hard life must have been for the Hohokam. Excavation of a platform mound and related sites on other freeway projects revealed that in the centuries before the Hohokam civilization collapsed it was subjected to repeated famines. In addition, most of the women suffered from anemia and bone thinning.

In order to sustain the population in the face of a 20 percent infant death rate, women probably bore children as soon as they were physically capable and stayed pregnant for most of their short lives. Even so, analyses show that the men ate most of the meat.

Such findings in the Hohokam area make the Tonto Basin even more important as a self-contained laboratory. The archeologists have marshaled the latest techniques to reconstruct a vanished world. Every artifact has been logged into a computer. Already scientists can call up the exact positions of 123,000 potsherds and 44,000 stone tools on a color-coded computer screen, which means they can compare instantly one site to another.

Machines that analyze the trace elements provide clues to diets, including everything from meat to water sources.

Arleyn Simon, who directs the chemical analysis of potsherds, has discovered multiple sources of the clays and pigments. She believes there were trade networks linking the Salado to other cultures stretching from Mexico to Colorado.

Detailed measurements of teeth can reveal genetic relationships between the Salado and other groups, including their modern Indian descendants.

Instruments that measure carbon can date the age of wood samples, enabling scientists to construct a chronology from bits of charcoal in ancient hearths.

Chemical analysis of things such as obsidian and turquoise can be used to pinpoint sources of precious minerals, helping archeologists reconstruct trade networks.

Workers at the Pinto Creek site (OPPOSITE PAGE) south of Roosevelt Lake dig down to uncover floor levels, doorways, and other architectural features.

(TOP, LEFT) Archeologist Tom Bodor records details of an unusual find in the Tonto ruins, an intact storage granary.

(TOP, RIGHT) Carol Edwards, left, and Dr. Arleyn Simon examine a recently discovered storage vessel. Such vessels often are kept intact with the dirt and any other materials packed inside. The finds are wrapped on-site and transported to the field lab where they are disassembled, cleaned, and put back together. The contents are analyzed for pollen and other organic substances.

(ABOVE) Some of the pottery storage vessels uncovered at Schoolhouse had a capacity of 55 to 60 gallons.

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Jamie Mereweather (FAR LEFT) cleans artifacts at the Pueblo Grande site, while clay effigies await his attention in the foreground.

(LEFT) Numerous tiny stone animal effigies were discovered at Tonto Basin. (LEFT, BELOW) Though small, the stylized effigies show remarkable variety, including, clockwise from top, a ceramic dog, Snowflake black-on-white, 6.5 centimeters long; an argillite dog, 4.0 cm; a steatite dog, 2.3 cm; and an argillite duck, 2.0 cm.

(RIGHT) Several rock-lined storage pits were found at Bass Point Mound, which was occupied during A.D. 1150-1300. In prehistoric times the mound was on a high bluff, but today, when Roosevelt Lake is at full capacity, it is surrounded by water. Petroglyphs are abundant on the rocky slopes around the site.

Microscopic analysis of pollen grains and other plant remains make it possible to reconstruct ancient diets, gauging the relative importance of irrigated crops and wild foods.

Computer data bases linking the width of the growth rings taken from thousands of trees enable scientists to reconstruct stream flow, year by year.

Of course, gathering the evidence and artifacts necessary to conduct all these tests remains tedious and time-consuming, a matter of whisk brooms, screens through which sweaty workers sift tons of dirt, dental tools for work around delicate artifacts, and inexhaustible patience. An archeological dig in progress simmers with slow-motion excitement.

The people who do the dirty work are a varied bunch of scientific vagabonds. Most have degrees in archeology and constantly move from dig to dig.

They are drawn by the thrill of ancient mysteries and the rush of insight.

They treasure the moments of contact with that vanished culture. Rice, director of ASU's effort, recalls the day he found a perfect palm print on one of those enigmatic pillars.

"There was a Salado hand from 900 years ago. That's the thing that's quasi-mystical. We aren't just studying pots and mud."

Already, they've unearthed ample evidence of a vibrant, creative culture. The Salado made beautiful pots, painted with elegant, curved designs suggestive of birds' wings and sunbursts, which they traded across the Southwest.

They labored over bits of shell to make wonderful necklaces, witnesses to farflung trade networks.

They fashioned droll figurines, marked sun-bronzed rocks with pictures of great artistry, and left puzzling bits of bone and polished stone that might have been intended for game boards and gambling.

You cannot stand in this thorned, sunseared desert valley without being sobered by the ingenuity of a people without wheels or metal who nonetheless filled great storehouses with food. They shrewdly reaped the bounty of a frost-free climate that offered rich wild-plant resources plus three plantings a year and the dependable drainage of 13,000 square miles.

And they profited from far-reaching trade networks, exchanging pots and wonderfully woven cloth for shells from Mexico and California, turquoise from across the Southwest, obsidian from neighbors, bright-green macaws from Mexico, and other goods from Colorado and New Mexico.

Clearly, Salado society became increasingly complex and stratified, farming the 44 miles of irrigatable streambed. Many lines of evidence converge: the shift from largely ceremonial platform mounds to bustling food storehouses, the first signs of upper-class houses atop the mounds, the concentration of weapons and precious resources such as turquoise at the later mounds, a gradual shift to evergreater reliance on irrigated crops, the emergence of such specialists as potters.

So what happened? Why did the Salado plunge from the peak of their success to extinction in what appears to have been a few short decades in the 1400s?

No one yet knows.

But they've already eliminated some possibilities.

No major shifts in the stream coinciding with the abandonment have been discovered, although Texas A&M geoarcheologist Mike Waters tried to find such a floodinduced deviation that might have destroyed the complex irrigation system. He noted that a series of wrenching floods scoured the valley some 3,800 years ago, but the river remained well-behaved during the crucial 1400s. Floods on tributaries might have forced the abandonment of some areas, like Pillar. But no signs of a basin-wide disaster have been uncovered.

The 1400s also brought no recordbreaking droughts, according to tree-ring studies. Small-scale droughts came and went, but that's not unusual in watershed where the runoff varies from 2.6 million acre feet to 162,000 acre feet per year. The Salado weathered repeated droughts during the centuries of their occupation of the valley.

The full picture won't emerge for several years, but the bits of evidence unearthed by scientists so far paint a compelling picture of a resourceful people who ultimately may have been overtaken by a disaster of their own making.

Perhaps the demands of the elite who dominated the platform mounds overtaxed the environment, suggested Charles Redman, ASU Anthropology Department chairman and coprincipal investigator for the Tonto Basin project. The power of the elite rested on the crop surpluses they controlled, which meant they probably pushed constantly for increased production. But in irrigation-based farming such stress on ever-increasing yields eventually leads to impoverishment of the soil and social collapse.

Perhaps the Salado simply grew so numerous and so dependent on irrigated crops that a drought they once would have weathered did them in, partly because centuries of overuse had denuded the wild resources of the basin. Perhaps they suffered some great epidemic when their population reached too high a density. The stream that nourished them might have become polluted, a breeding ground for disease.

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Or perhaps their society became too competitive and class-conscious, slipping into warfare as the insecure elite atop the platform mound grabbed for more power. The archeologists have found some evidence of escalating violence, including the discovery of one outlying settlement that evidently was raided and burned, its inhabitants killed.

But it would be unfair to let the riddle of their disappearance overshadow the accomplishments of a people who thrived for a thousand years in an environment so rigorous it could kill an unequipped modern urbanite in a matter of hours.

Truth be told, people like Rice, Jacobs, Simon, and Lindauer are more driven by the question of how the Salado lived than how they died. “In archeology,” Lindauer said, “you live for that time when you pick up something that's been hidden for a thousand years, and suddenly that vast amount of time is narrowed to the moment you touch what they left.” Or perhaps the moment the summer-solstice sun illuminates a sacred place on an ancient wall for the first time in 10 centuries. That's exactly what happened at dawn on the longest day of the year when the ASU archeologists and assorted hangers-on proved that the Pillar site had indeed been built as a calendar of mud and stone and hope.

The archeologists converged on the site just before dawn, scurrying about to set up video recorders and measuring poles, glancing repeatedly over their shoulders to the east where the sun would rise.

Then, the sun broke the crest of a distant ridge, and the morning light streamed through the doorways of the excavated temple and suffused the squat pillars. A dagger of light appeared on the back wall, then inexorably lengthened.

After perhaps 10 minutes, the point of the dagger had crept to the base of the pillar, resting there a moment as the harbinger of the seasons came once more to its proper place.

A thousand years ago, priests probably chanted as the light moved across the floor, perhaps illuminating small tableaus of sacred objects. But the archeologists simply watched, sensing the gathered ghosts.

Someone blew a note on a conch shell, echoing with time and lost worlds. The earth turned.

The sun rose.

The light retreated from the pillar. And if the spirits of the Salado still reside in the land they loved, they would have been reassured to see the sun has kept to its duties, although the proper prayers have been neglected for so very long.

Archeology Open House: The Cline Terrace Platform Mound (off State Route 188 just north of Roosevelt Lake, near Punkin Center) will be open to visitors Saturday, February 29, 1992, from 10:00 A.M. to 4:00 Р.М.

The open house is a unique opportunity to learn about the tools and techniques archeologists are using to learn about the Salado Indians who lived in the Tonto Basin. Activities include tours of the site, viewing of on-going excavations, a visitor dig, and demonstrations of prehistoric crafts. Admission is free.

For directions and additional information, telephone archeology Project Manager Brenda Shears at ASU, (602) 965-7181.