In the Mesa Verde region the people were also learning to build in sandstone, but the available standstone was coarser than that in Chaco and did not have the clean fracture planes, and the masonry was of a thicker and seemingly cruder sort. Walls were made of rectangular blocks of tan sandstone which quite often were carefully shaped and ground to give a pleasing effect.
On the sloping green tabletop mountain, known as the Mesa Verde (from which the surrounding area gets its name), in the early part of this period (A.D. 1050-1200), the people built large unit-type pueblos upon the long finger-like mesatops which extend southward from an abruptly rising escarpment on the north. Most of these units were multistoried, and although they centered around a central plaza, they were much smaller, more tightly contained units than their Chaco Canyon counterparts of the same period. Frequently they contained at least one towerlike structure connected by an underground passage to a nearby kiva. One or more other kivas might be located in, or front on, the small central plaza.
Although the rooms are smaller than the ones in the great communal houses of Chaco, they are solidly built of double course standstone blocks. Because in most cases the mesas are sloping southward, many of these unit houses were built upon one or more terraced flats. Frequently the only entrance into the pueblo was by staired entranceway leading from the south into the small interior court or plaza.
At Mesa Verde, in the latter part of this period (about A.D. 1200-1225), the people who had been living on the mesatops in the unit house type of dwelling seem suddenly to have abandoned these dwellings and taken up residence in the nearby caves. Here they built great pueblo-type structures, often of several hundred rooms with numerous associated kivas. Since they were limited by the ceiling of the caves to two and three-story structures, and not so exposed to the elements, it was not necessary to use such thick, strong walls, roofs, and ceilings. The general construction at Mesa Verde was therefore thinner than at Chaco, and the rooms and doorways are considerably smaller. In fact, with the warm southern exposure of the caves which were used, the people must have done most of their living and daily chores outside, in the small plaza areas and on the roofs of the lower tiers of rooms. The rooms themselves could be small, for they were probably used only for sleeping and storage. Because the native sandstone at Mesa Verde is coarser grained and does not fracture as easily into blocks and spalls, the style of alternating large and small banded masonry found at Chaco was not adopted there. But much of the stonework at Mesa Verde is nonetheless excellent; perhaps some builders had greater artistry than others, for some of the rooms, especially the circular towers, contain blocks which have been carefully pecked, ground, polished, and fitted into exact position with loving care.
In this period, also, a structure known as a Great Kiva comes into prominence. It usually has an entrance on the north side (instead of through the smoke hole), often with a stairway. It has a large raised firebox in the center of the south side, and occasionally another entrance there. In addition, on the east and west sides of the floor are large, rectangular stone-lined pits, built up above the floor. Their exact use is still a mystery, and perhaps they served more than one purpose. It has been suggested that when covered with boards, they would make excellent foot drums for the dances, or good places for the medicine men to conceal themselves while performing certain magical rites during initiation ceremonies. Finally, four large posts set into the floor of the kiva supported the roof. Great Kivas are fairly common in the Chaco area, but in the Mesa Verde vicinity they seem to be very rare.
In each of the two areas mentioned above—Chaco Canyon and Mesa Verde—archeological work has revealed a continuous occupation of the sites and the immediate vicinity. At the great Aztec ruin, however, there is still some doubt as to what really happened. In two different time periods there seem to be strong architectural relations to both the Chaco and Mesa Verde centers, as well as close ties in ceramics and other items of material culture. Part of the intriguing mystery at Aztec is whether these similarities represent actual migrations from those centers on a fairly large scale, or an exchange of ideas, or small groups of migrants who strongly influenced the local population.
In the midst of the populous Animas Valley, along the edge of an old river terrace, early in the 1100’s a large multistoried stone pueblo was built in an architectural style reminiscent of that in Chaco Canyon. Did a large migrant group from the Chaco area—or some other area where Chaco-like people were living—move into the Animas Valley and erect this structure? Or did some of the local citizenry decide to join in a community effort and copy the building techniques of their neighbors to the south? If so, what was the impetus which launched the local people upon this ambitious project? Perhaps a small group of highly skilled technicians, under the leadership of a few “priests” or medicine men, came from the Chaco area into the Animas Valley. Once established there, by persuasion, teachings, or by religious magic and psychological control, they may have prevailed upon some of the local population to join them and to build their homes and kivas of sandstone blocks, in the traditional Chaco style.
We may never know the exact answer to these questions, but wherever the people came from, whoever they may have been, whatever the guiding impetus, Aztec pueblo, like Rome, was not built in a day. Dates from tree rings—as described later—indicate that the pueblo was built between A.D. 1110-1124, with the major construction periods in 1111 and 1115. Probably a small group, or just a clan, moved into the site about 1110, and finding it suitable for habitation erected the first small part of the pueblo. The next year a much larger group, perhaps several clans or more, joined the earlier settlers and more than 50 percent of the pueblo was finished. Then, in 1114 or 1115, a third wave of migrants arrived and essentially completed the pueblo, except for the one-story row of rooms which closed off the south side. It is possible that some of the indigenous Animas population joined these newcomers and moved in with them. From 1115 until about 1124 or 1125, occasional rooms were added as new quarters were necessary for newly married couples and as old rooms were used as refuse dumps.
To the northwest of the ruins, less than 2 miles away, the Indians found an outcropping of sandstone which could be broken into shape and then ground into rectangular blocks. These were hauled to the proposed building site, where the women took over the construction. Holes were dug in the clay soil nearby, water poured into them, and then stirred to produce a thick adobe mud. This was used, along with crude unshaped sandstone blocks, as filler for the walls. On the outside, the women laid up the well-shaped blocks in regular courses, chinking them with small spalls or potsherds.
The rooms were laid out in rows adjoining one another; as one row was finished, another was added alongside of it. When several rows had been completed, second and possibly even third stories were added. The first group to arrive probably completed the major part of one wing; later groups added to this and erected the other wings and associated kivas until the entire pueblo had the traditional planned aspect of a typical plaza-enclosed Chaco pueblo. In the central plaza area several kivas were dug and roofed over at ground level. The fourth side consisted of a single row of one-storied rooms. Finally, even a fourth story may have been added in places. Sometimes a large square space was temporarily left open, later to be filled by a circular kiva.