As was noted in the preceding section, a few surface houses were built in the Modified-Basketmaker period, but this type of architecture did not become well established until Developmental-Pueblo times. In the beginning of the period, in most areas, pit houses were still the usual form of dwelling. To the west and north of these houses, granaries were built with superstructures in the form of truncated pyramids. Sometimes stone slabs and sometimes crude masonry were used in their construction. Later, jacal structures as well as pit houses served as dwellings. The name _jacal_ is applied to a type of construction in which walls are made of poles set at short intervals and heavily plastered with adobe. At first, walls sloped inward, as they had in the superstructures of the earlier granaries from which it is believed that this type of house was derived. Later, walls were perpendicular and the jacal construction was sometimes combined with masonry. Still later, masonry was used almost exclusively. As time went by, floors became progressively less depressed. In early forms, rooms were not connected, but eventually contiguous rooms became the rule, and, in the course of time, there arose multiroomed structures, sometimes called _unit houses_. Associated with these were highly specialized subterranean structures, used for religious purposes, but apparently derived from the old domiciliary pit house. It cannot be stressed too strongly that these are all general statements, designed solely to show evolutionary trends during this period. Actually the situation is far more complex than this would indicate. In some sections, big pueblos were built very early in the period.[7] In peripheral regions, pit houses continued to be used as dwellings long after they had ceased to serve such a purpose in the main area, and, even in the nuclear portion, the rate of progress was by no means constant, nor was it always in the same direction. For a somewhat clearer picture, it is best to consider some of the different places where excavation of Developmental-Pueblo sites has been undertaken. At Kiatuthlana, Arizona,[107] forty miles southwest of Zuñi, pit houses and jacal structures were contemporaneous during early Pueblo times. The latter were flat-roofed, four-sided buildings, trapezoidal, rather than rectangular, in outline. Some were single rooms, and others had three or four chambers.