In the Piedra district of southwestern Colorado[106] are found jacal buildings in clusters of from three to fifteen. The different structures were often close, but did not touch. A number of clusters, laid in a crescent shape around a circular depression, comprised a village. These depressions are thought by some to have served as reservoirs, or possibly sometimes as plazas or dance courts. Others hold the opinion, based on the results of more recent excavations in other areas, that they may contain pit houses.[41] The earliest houses were pits with sloping jacal walls. Later the floors were merely depressed, and walls were perpendicular. This type was eventually combined with two-room storage buildings of crude masonry. Next, the jacal construction disappeared and the rooms made of masonry were enlarged and became dwellings instead of storerooms. In the nearby region of the La Plata drainage,[95] houses in the beginning of the period differed little from those of Basketmaker times, except that they were somewhat more massive and more masonry was used. There was some jacal construction, but usually a variant form was employed in which only a few widely spaced wooden supports were used. Sometimes the entire wall consisted of clay pressed into position with the hands, and the posts were absent. Stones were sometimes added to the clay, and some crude coursed masonry has been found. Stone slabs commonly formed the wainscoting. Houses were usually grouped in a crescentic form along the north and west sides of a depression containing a subterranean chamber. No dance courts or plazas have been found. During the latter part of Developmental-Pueblo times in the La Plata area, jacal and slab construction were replaced by stone and adobe, and walls became more massive. At first the adobe was considered the important mass and only a few stones were incorporated, but, as time went by, the ratio changed and stone predominated with mud serving only as a mortar. Crescent-shaped room-placement changed to a rectangular structure. In the Ackmen-Lowry region[82] of southwestern Colorado most early Developmental-Pueblo sites consisted of one or two above-ground rooms associated with a pit house which may have served as a domicile as well as provided a place for the celebration of ceremonies. The surface structures were of slabs topped by masonry, or were of jacal construction. Later houses were built of coursed masonry and usually contained from four to six rooms. The associated pit houses seem to have been used exclusively as ceremonial chambers. Also found in this area was a good-sized Pueblo, known as Lowry Ruin, which was occupied late in Developmental-Pueblo times as well as during the succeeding period. Thirty-five rooms have been uncovered, but there is evidence that the pueblo was modified six or seven times, and it is estimated that probably no more than fifteen or eighteen rooms were occupied at any one time.