The masonry of these villages was roughly constructed, the walls being often less than a foot thick. Very little adobe mortar seems to have been used; some of the thickest and best preserved walls have apparently been laid nearly dry (Pl. LXI). The few openings still preserved also show evidence of hasty and careless construction. Over most of the area the debris of the fallen walls is very clearly marked, and is but little encumbered with earth or drifted sand. This imparts an odd effect of newness to these ruins, as though the walls had recently fallen. The small amount of debris suggests that the majority of these buildings never were more than one story high, though in four of the broadest clusters (see plan, Pl. LX) a height of two, and possibly three, stories may have been attained. All the ruins are thickly covered by a very luxurious growth of braided cactus, but little of which is found elsewhere in the neighborhood. The extreme southeastern cluster, consisting of four large rooms, differs greatly in character from the rest of the ruins. Here the rooms or inclosures are defined only by a few stones on the surface of the ground and partly embedded in the soil. There is no trace of the debris of fallen walls. These outlined inclosures appear never to have been walled to any considerable height. Within one of the rooms is a slab of stone, about which a few ceremonial plume sticks have been set on end within recent times. [Illustration: Plate XLI. Back of Oraibi house row.] The motive that led to the occupation of this mesa was defense; the cause that led to the selection of the particular site was facility for procuring a water supply. The trail on the west side passes a spring half way down the mesa. There was another spring close to the foot trail on the south side; this, however, was lower, being almost at the foot of the talus. In addition to these water sources, the builders collected and stored the drainage of the mesa summit near the southern gap or recess. At this point are still seen the remains of two reservoirs or dams built of heavy masonry. Only a few stones are now in place, but these indicate unusually massive construction. Another reservoir occurs farther along the mesa rim to the southeast, beyond the limits of the plan as given. As may be seen from the plan (Pl. LX) the two reservoirs at the gap are quite close together. These receptacles have been much filled up with sediment. Pl. LXII gives a view of the principal or westernmost reservoir as seen from the northeast. On the left are the large stones once incorporated in the masonry of the dam. This masonry appears to have originally extended around three-fourths of the circumference of the reservoir. As at Ketchipauan, previously described, the upper portion of the basins merged insensibly into the general drainage and had no definite limit.