Casa Grande Ruin | Page 6

the center of the eastern side of the terrace, and also on the western side, the water which falls on the surface of the structure is discharged through rather pronounced depressions at these points. These depressions are not the work of running water, though doubtless emphasized by that agency, but represent low or open spaces in the original structure, probably passageways or gateways. Furthermore, before or inside each gateway there is a slightly depressed area, just where we would expect to find it under our hypothesis, and showing that the process of filling in is not yet completed. If the structure were to remain undisturbed for some decades longer these spaces would doubtless be filled up from material washed from the mounds, giving eventually a continuous slope from the base of the mounds to the edge of the terrace.
On the eastern margin of the map and in the southeastern corner two small and sharply defined mounds, differing in character from any others of the group, are represented. That shown on the eastern margin rises about 6 feet and the other about 10 feet above the surrounding level, and both stand out alone, no other remains occurring within a hundred yards in any direction. These mounds seem a thing apart from the other remains in the group; and it is probable that they represent the latest period in the occupancy of this site, or possibly a period subsequent to its final abandonment as a place of residence. Analogous remains occur in conjunction with some large ruins in the north, and there they represent single rooms, parts of the original structure kept in a fair state of preservation by occasional repairs while the remainder of the village was going to ruin, and used as farming outlooks long after the site was abandoned as a place of residence. As these farming outlooks have been discussed at some length in another paper[1] it is not necessary here to enlarge upon their function and the important part they play in Pueblo architecture. If the high mounds in question mark, as supposed, the sites of farming outlooks such as those which are found in the north, they indicate that the occupancy of the region in which they occur was continued after the abandonment of the Casa Grande structure by the people who built it or by people of similar habits and customs.
[Footnote 1: A Study of Pueblo Architecture; 8th Ann. Rep. Bur. Eth., 1891, pp. 86, 227, and elsewhere.]
An inspection of the map will show a number of depressions, some of quite large area, indicated by dotted contour lines. The principal one occurs a little west of the center of the area, and is worth more than a passing notice since similar structures are widely distributed throughout this region. It may be roughly characterized as a mound with excavated center. The ground for some distance about the structure (except for two depressions discussed later) is quite flat. From this flat surface as a base the structure rises to a height of 5 feet. From the exterior it has the appearance of an ordinary mound, but on reaching the top the interior is found to be hollowed out to a depth which even at the present day is below the surrounding surface, although not below the depressions adjoining. The main structure or mound is shown in figure 329 (an enlargement from the map). It measures on top of the crest 150 feet from north to south and about 80 feet from east to west, but covers a ground area of 200 feet by 120 feet or over half an acre. The crest is of the same height throughout, except for slight elevations on the eastern and western sides and a little knoll or swell in the southwestern corner. There is no indication of any break in the continuity of the crest such as would be found were there openings or gateways to the interior. The bottom of the depression in the main structure is at present about a foot below the surrounding ground surface, but it must have been originally considerably more than this, as the profile indicates long exposure to atmospheric erosion and consequent filling of the interior. No excavation was made and the character of the construction can not be determined, but the mound is apparently a simple earth structure--not laid up in blocks, like the Casa Grande ruin.
[Illustration: Fig. 329.--Map of hollow mound.]
[Illustration: Pl. LIII: General View of Casa Grande.]
To the east and to the west are two large depressions, each about 5 feet below the surrounding ground surface, evidently the places whence the material for the construction of the mound was obtained. Yet the amount of material removed from these excavations must have been considerably in excess of that used in the construction