At the close of this period, what were conditions in the lower Animas Valley, especially in the immediate vicinity of what is now the Aztec Ruins? Was there a small, early-type Developmental Pueblo Village at this particular spot? Or possibly a large “unit house” type structure? Lack of knowledge about the Animas Valley precludes a definite answer, and early excavations at Aztec Ruins were largely confined to the main ruins themselves. In most places the digging did not penetrate to what may have been the underlying and earlier remains. In a few places beneath the great ruins, where the excavations went deep enough and where the later building of the great pueblo had not eradicated them, there seem to be indications that there were kivas of an earlier type, and possibly a few scattered aboveground dwellings. An early-type Developmental Pueblo village may have stood at this same spot. THE AZTEC PUEBLO. At the beginning of the Great Pueblo Period in the Animas Valley there may well have been a sizeable population living in scattered unit house dwellings and small villages, built largely of river cobbles and adobe mud. The area to the south of Aztec, in and around Chaco Canyon, and that to the northwest, in and around Mesa Verde, had each developed local variations in architectural style, religious concepts, and minor arts and crafts. Cultural influences from these two areas were to have a marked effect upon the large pueblo at Aztec that was built, abandoned, and reoccupied during this period. [Illustration: Chaco-style masonry wall.] The Chaco Wash (today a dry streambed during much of the year) rises in the high plains north of the Chacra Mesa, extends westward for 68 miles, and then twists sharply to the north to join the San Juan just above Shiprock, N. Mex. For about 20 miles it flows westward through a beautiful yellowish-brown sandstone canyon, the cliffs of which step back in a series of gigantic sandstone ledges. In places the canyon bottom is broad and level, but today it is scarred by a deep arroyo with branches which extend up each little side canyon, so that travel on foot across or up and down the canyon is difficult. A thousand years ago this arroyo did not exist, and the Chaco Wash was a shallow, clear-flowing year-round stream, meandering through a lush green valley. Where today the sandstone ledges stand starkly denuded of all trees, there was once a dense forest of pines and junipers. Along this canyon bottom and on the mesatops to the north and south, the prehistoric Chacoans erected some of the finest sandstone masonry pueblos in North America. A number of other large Chaco-like sites were built in places outside the canyon proper, and the influence of this building style was felt for 50 miles around.