om above, and possibly the profile of the
mounds was already established, being only slightly modified by surface
erosion since.

[Illustration: Pl. LII: Ground Plan of Casa Grande Ruin.]

About 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