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 of the mound, and this excess
was doubtless utilized in neighboring constructions, since it is hardly
to be supposed that it was carried away to any considerable distance.

The purpose of this hollow mound, which is a fair type of many similar
structures found in this region, is not clear. Mr. Frank Hamilton
Cushing, while director of the Hemenway southwestern archeological
expedition, found a number of these structures and excavated some of
them. From remains thus found he concluded that they were sun-temples,
as he termed them, and that they were covered with a roof made of coiled
strands of grass, after a manner analogous to that in which pueblo
baskets are made. A somewhat similar class of structures was found by
the writer on the upper Rio Verde, but these were probably thrashing
floors. Possibly the structure under discussion was for a similar
purpose, yet its depth in proportion to its size was almost too great
for such use. The question must be left for determination if possible by
excavation.

In the southern central part of the map is shown another excavation,
covering a larger area than any of the others, of very irregular outline
and from 3 to 4 feet deep. It is apparently older than the others and
probably furnished the material for the house structures northeast and
southwest of it. Bordering the depression on the south there are some
low mounds, almost obliterated, which probably were the sites of other
house structures.