Unfortunately, the Animas is one of the river valleys in the San Juan drainage which has not been particularly well surveyed or investigated archeologically. Accounts by early settlers, and passing references in some of Morris’ reports, indicate that in aboriginal times (certainly during Pueblo times), the valley was no doubt heavily populated. It should have been. Good water is readily available in the river and the climate is healthful; prehistorically, game must have abounded in the nearby foothills and mountains. Settlement and clearing of lands in more recent times have eliminated many of the prehistoric remains, but the higher banks along the river terraces still show low mounds of rubble, obviously man made, with indications of cobble and sandstone walls, which evidently were dwellings of the Pueblo Period. Best known in this valley area are the cave and open sites that Morris excavated north of Durango and which contained the remains of early Basketmaker peoples already mentioned and the great pueblo of Aztec, near the town of the same name about 15 miles above the confluence of the Animas and San Juan Rivers. As described elsewhere, this latter structure was also excavated by Morris in 1916-21. Without doubt, parts of the valley were more or less continuously occupied from early Basketmaker times until the final abandonment of the Four Corners country about A.D. 1300. Although we have no firm data on which to base conclusions, it would be safe to assume that the Developmental Pueblo Period in the Animas Valley lasted from about A.D. 750 or 800 to 1050 or 1100, and that conditions in the living patterns of the people elsewhere were reflected in the Animas Valley. As the Developmental Pueblo Period progressed, house arrangements became more complex. The next step seems to have been an extension of the earlier linear or crescent-shaped alinement of contiguous houses by adding on one or more wings, so that the resulting plan was L-shaped or formed a rectangular U. In these cases, the semisubterranean kiva was still retained in the courtyard as a definite religious structure. These types of planned communities are called “unit houses.” Most were single storied, though some may have had a second story added on the back tier of rooms.