On the other hand, there is the hypothesis that these depressions represent house structures; but if so these structures are anomalous in this region. The contour of the ground does not support the idea of a cluster of rooms about a central court, nor does the débris bear it out. Mr. F. H. Cushing has found depressions in the valleys of Salt and Gila rivers somewhat resembling these in form and measurement, and situated always on the outskirts of the sites of villages. Excavations were made, and as the result of these he came to the conclusion that the depressions were the remains of large council chambers, as the floors were hard, plastered with mud, and dish-shaped, with a fire-hole in the center of each; and no pottery or implements or remains of any kind were found except a number of “sitting stones.” Mr. Cushing found traces of upright logs which formed the outer wall of the structure; he inferred from the absence of drainage channels that the structure was roofed, and as the ordinary method of roofing is impracticable on the scale of these structures, he supposed that a method similar to that used by the Pima Indians in roofing their granaries was employed, the roof being of a flattened dome shape and composed of grass or reeds, formed in a continuous coil and covered with earth. If the depressions under discussion, however, are the remains of structures such as these described, they form a curious anomaly in this region, for, as has been already stated, the affinities of the remains of this region are with the northern architectural types, and not at all with those of the southern. There is a third hypothesis which, though not supported by direct evidence, seems plausible. It is that the depression of Clear creek, and perhaps also the one on the opposite side of the Verde, were thrashing floors. This hypothesis accords well with the situation of these depressions upon the tillable bottom lands, and with their relation to the other remains in their vicinity; and their depth below the surface of the ground would be accounted for, under the assumption here made of their use, by the high and almost continuous winds of the summer in this region. Perhaps the slight depressions at the northern and southern side of the oval were the gateways through which the animals which trampled the straw or the men who worked the flails passed in and out. Whether used in this way or not, these depressions would be, under the assumption that the bottom was plastered with mud, not only practicable, but even desirable thrashing floors, as the grain would be subjected during thrashing to a partial winnowing. This suggestion would also account for the comparatively clean ground surface about the depressions and for their location on slightly elevated knolls.