IT DOMINATES THE SKYLINE AND DWARFS MERE MORTALS as they lift their eyes from the valley floor to its two-thousand-foot cliffs and steeply ridged slopes. What they see is Mesa Verde, named by lost generations of Spaniards when they first perceived it as a "green tableland." For travelers coming from the east, a rock promontory intrudes into the view of the valley. The aptly named Point Lookout would have made a superb castle site for a feudal knight from which to survey his fiefdom and repel challengers to his temporal power. But when armored barons were lording it over Europe, a much gentler people were roaming the green mesas in the New World to hunt and eventually settle. They grew crops and built communities, all without the trappings made possible for their European contemporaries by the use of iron.

From the north, Mesa Verde appears to forbid entry, but here first impressions deceive. From the rugged northern escarpment, the mesa slopes gently southward toward the Mancos River, which carved the mesa's canyon eons ago. In fact, Mesa Verde has been described as an almost classic cuesta (another word of Spanish origin), a land elevation with a gentle slope on one side and a cliff on the other. The Mancos River flows out of the La Plata Mountains and meanders across the broad Mancos Valley, from there to be clutched by mesa and mountain and then released into a deep trench that circles Mesa Verde to the south. From this curving main canyon, numerous finger canyons slash into Mesa Verde's southern rim, giving birth to small mesas that, taken together, form the larger unit. Some canyons climb slowly almost all the way to the northern crest; others rise more steeply to dissolve into the mesa's heartland. Erosion has carved shallow caves into canyon walls and never stops shifting and shaping. Mesa Verde, after all these millennia, is still changing.

It was at least two thousand years ago, long before the Spanish came, that the Indians first appeared and disturbed nature's busy stillness. They must have been intrigued by the unusual rocks and soil that they found; centuries later geologists would classify the basal rock as Mancos shale, a deep marine deposit from the time when all this land was under water. The overlying sandstone gives the mesa its colors, which range from gray to yellow-orange, complemented by a deep layer of rich, red aeolian soil that covers the mesa ridges. All that the virgin land needed to make farming possible was water and someone to till it.

The climate and vegetation varied considerably then as now, because elevations on the mesa range from 6,000 to 8,500 feet. For anyone who ventures into these canyons unprepared, water is more precious than gold, although Mesa Verde is neither as dry as its neighboring valleys and plateaus nor as dry as much of the larger semiarid area in which it sits, a borderline component of the American Southwest. Adequate winter moisture is critical to survival of vegetation, animals, and humans. Except for the Mancos River, the streams that carved these canyons dry up in the summer heat, and precious few springs come to the rescue. The hot summer days drive the animals to the shade, and the cold winters lure them down into the warmer, sheltered canyons. Thus does nature observe the changing seasons.

The variations in vegetation at Mesa Verde are noticeable even to the most casual observer. The lower, or southern, portion of the mesa supports piñon pine—Utah juniper forests, whose dark green color probably gave rise to the mesa's name. They cover about half of the park lands and, at the right season, perfume the canyons and mesas with their fragrance, as do some of the less dominant wildflowers. The delicate blue lupines, vivid cactus blossoms, and spindly cliff roses of Mesa Verde provide a connoisseur's delight, although some visitors proclaim the mariposa lilies the loveliest of all. At higher elevations Gambel oak, serviceberry, sagebrush, and other mountain shrubs vie to cover what the piñon and juniper do not. A few Douglas fir, ponderosa pine, and aspen have taken hold where the moisture and climate suit their individual needs.

Through them all scurry sundry desert and mountain creatures and overhead soar a wide variety of their winged counterparts. Long after all this land became a national park, observers counted approximately 175 species of birds flying over and nesting in Mesa Verde.

Each season at Mesa Verde has its own beauty, as visitors have discovered—and all who come here are visitors. No one has permanently conquered this boldly deployed outpost between mountains and deserts, valley and river. Spring is shortchanged; winter turns into early summer almost overnight. But when the snows melt and the rains come, when the grasses grow and the flowers bloom, most people agree that it is a beautiful country. That lushness lasts all too briefly; the hot sun and warm winds soon parch mesa and canyon as summer settles in. The early, colorful fall days, with their crisp nights, end that season and herald winter's coming. Winter holds the most surprises for even the experienced visitor; its temperatures and weather can encompass all four seasons.

Time had no meaning, no beginning, no ending, and no name at Mesa Verde—until human beings arrived. A thousand years could have been only a moment in yesterday's time, as the pattern of seasons succeeded in endless cycles. At some point several millennia ago, historic time suddenly jarred nature's serenity, providing a point of departure for a new story; human beings walked and climbed into Mesa Verde. What they called themselves we do not know. They apparently had no written language; certainly none survives. To give them a name and reference, we have called them hunters and gatherers, basketmakers, cliff dwellers, and Anasazi (Navajo for "ancient ones"). The exact time of their arrival has eluded scholars, who have established it as roughly two thousand years ago. Modern researchers remain determined to establish a firm date, and the search continues.

Hunters and gatherers drifted in first, depending on wild animals and nature's bounty for food; they lived in caves or on the canyon floors. Eventually some of them changed their nomadic life and evolved into an agricultural people. When the hunt was abandoned and a reliance on crops superseded hunting and gathering, settlement came to the Mesa Verde region.

In time, these prehistoric people evolved into what we know as the basketmakers, a reflection of their impressive skills. Before their era ended, about a.d. 750, settlement had extended into Mesa Verde proper. By then, they had abandoned caves and were living in pithouses that were clustered into small villages, usually built on the mesa top. They had also mastered the techniques of making crude pottery and the bow and arrow. Farming methods had improved, harvests had increased, and their life in general had become better. The population increased correspondingly, and life assumed a rhythmic seasonal pattern.

Slow changes modified that life pattern, and in the Pueblo period, forsaking their pithouses, they experimented with building houses above ground. These eventually became so-called apartment houses several stories high. By about a.d. 1000, the Anasazi had advanced from using rather crude pole-and-adobe construction to the skillful stone masonry for which they are justly famous. The pithouse moved underground and became the kiva, a Hopi word used by archaeologists to describe the room that resembles the modern-day Pueblo ceremonial chamber. An adjunct to the kiva was the sipapu, or small opening into the ground, symbolizing the entrance to the underworld, or Mother Earth. All signs indicate the kiva's primary purpose was for religious ceremonies, but it was probably also used for recreation.

In this period pottery making steadily improved, as did farming; corn, beans, and squash dominated, as much of the mesa-top land was cleared for cultivation. There is evidence that agricultural water-management techniques—check dams and storage reservoirs—helped to compensate for the semiarid environment. The Anasazi traded extensively for such items as seashells, turquoise, cotton, and salt, none of which were found near Mesa Verde.

Their wide-ranging commerce indicates the advancements of these ancient people. At the same time, however, many things about them remain inscrutable. Their accomplishments were achieved without a system of writing, horses, or other livestock (they domesticated only the turkey). Nor did the Anasazi ever develop the wheel or the use of metals. Yet, from their simple hunter-gatherer beginnings, they built a complex culture that reached its zenith in the years from a.d. 1100 to 1300, known as Mesa Verde's classic period, the golden age of the Anasazi. During this period the pueblo dwellings became larger and more concentrated, forming compact villages of many rooms. The several thousand people who may have lived on the mesa represented only a small part of a much larger population that inhabited villages scattered for many, many miles in all directions in the surrounding region and south to the intriguing development centered in Chaco Canyon.

Throughout these golden years, the level of craftsmanship in masonry, pottery, weaving, and jewelry rose markedly. Towers appeared for the first time. The massive stone walls of the large pueblos represent the finest workmanship at Mesa Verde; each stone was carefully laid in a neat, even course.

Then, in the midst of this progressive era, a most startling reversal occurred. There began a major shift of the population back to the caves that had been abandoned centuries before for the more open, healthful, and accessible mesa-top sites. The reason for this change continues to be one of the great mysteries of Mesa Verde. Paradoxically, here within these confined caves, facing building problems more challenging than those on the mesa top, the Anasazi builders produced their architectural masterpieces. The hundreds of cliff dwellings that remain attest to the magnitude of the migration from the mesa-top pueblos. Cliff Palace, with over two hundred rooms, was the largest; others were tiny, one-room structures. Against the back walls of the caves stood the largest apartment houses, rising three and four stories. Structures of this scale and complexity would not be seen again in the United States until the 1870s, hundreds of years later. The quality of the masonry construction and the interior plastering and painting of the walls in red and white demonstrate techniques refined far beyond anything known before. Architecturally, no standard ground plan emerged—the builders simply adjusted to the available space.

The urban concentration that resulted was to be unequaled for centuries. Not only were the inhabitants crowded together in limited space—they devoted what seems to be a disproportionately large share of the space to their kivas. There are twenty-three of them in Cliff Palace. Life could not have been easy—climbing up to the fields each day or clambering down to reach water sources must have taxed young and old alike. One wonders how young children were kept from tottering over the edge of the precipitous cliffs and whether the overcrowding in the caves proved vexing after the spaciousness of the mesa top.

The possible causes for this migration have perplexed archaeologists and historians for decades. One obvious explanation lies in the defensibility of the sites; the cliff dwellings provided an uncommon measure of security for their inhabitants. The weather might also explain the move. The mesa tops, with their higher elevations, were colder in winter; the caves, lower and with southern or southwestern exposures, would have been warmer and sheltered from the wind. Perhaps some religious or psychological reasons motivated the movement. With or without a reason, however, these ancient people gave Mesa Verde the cliff dwellings for which it is now famous.

Strangely, after all the work required for relocating and rebuilding, the Anasazi lived in their new homes for only a few generations. By a.d. 1300, the cliff dwellings had been abandoned, and the people had disappeared. They may have traveled south into what would be New Mexico and Arizona and become the ancestors of some of the modern Pueblo Indians.

Their exodus created another great Mesa Verde mystery: What impelled them to leave? Perhaps it was an extended drought that settled over the area in the years from 1272 to 1299, a devastatingly long time for farming Indians to experience repeated crop failures. The inevitable stresses and social unrest of congested urban living may have constituted a psychological reason for leaving. The population growth had put intense pressure on the land and its resources. The Anasazi may simply have over-exploited their environment and exhausted the soil, the forests, and the animal supply, leaving themselves facing bleak prospects even without the drought. The deforestation of the mesa, in all likelihood, led to serious silting and soil erosion. Long-range concern for the environment seems not to have played a role in these people's lives; pressing daily needs undoubtedly overwhelmed any thought of the future. Today we realize that they failed to be stewards of their resources; seven centuries ago that concept had not yet arisen.

Another plausible explanation for both the migration and the abandonment is the possibility that an outside enemy pressured them to move first into the caves and then, when the threat became unbearable, ultimately to flee altogether. No evidence, however, has been uncovered to support the theory that conflict was associated with the abandonment. Without a doubt, overcrowding could have rendered the Anasazi susceptible to all kinds of pressures, including disease. In the face of all these misfortunes, the Anasazi may have thought their gods had deserted them; a change of location could have been a desperate gamble to reverse their fortunes. Most likely, a combination of both natural and manmade conditions motivated them to wander away. Their culture, which had promised so much and advanced them so far, suddenly fell apart. Such severe trauma could not have occurred without terrible individual and group wrenchings. The number of things they left inside their homes makes it appear likely that they seriously expected to return when times improved.

For whatever reasons, the people departed. By the end of the thirteenth century, the cliff dwellings had become ghost towns. When the last Anasazi walked out, silent shadows settled over Mesa Verde. It was to be many centuries before another party would return, discovering the rich heritage that the Anasazi left behind.