The large building in Hackberry Canyon, one of the terminal spurs of
Bridge Canyon, a mile northeast of the cluster in Holly Canyon, is
particularly instructive from the fact that surrounding the remains of
a circular tower, for two-thirds of its circumference, is a concentric
wall with compartments separated by radial partitions (fig. 12, 1).
[Illustration: FIG. 12.—Horseshoe (Hackberry) Canyon.]
Horseshoe House (pl. 23, _c_) stands on the north edge of the canyon
(fig. 12, 1), having its straight wall on the south side, as is usually
the case, the well-preserved north side being curved. The northeastern
corner still stands several feet high. The southeastern corner formerly
rested on a projecting rock, which recalls the cornerstone of Sun
Temple. The masonry of most of the southern segment of the enclosed
circular room or tower has fallen down the cliff. There does not
appear to have been a doorway on the south side, and there is not space
for rooms on this side on account of the nearness to the edge of the
cliff. While the form (fig. 13) of Horseshoe Ruin recalls that of Sun
Temple, in details of room structure it is widely divergent. The length
of the south wall, or that connecting the two ends of the horseshoe,
is 30 feet, its width 27 feet; the highest wall on the northwest side
is 12 feet. Figure 13 shows the arrangement of the rooms and the
mutilation of the south wall of the ruin. The distance between the
outer and inner concentric walls averages 4 feet; the circular room is
17 feet in diameter.
In the same cluster as Horseshoe Ruin (pl. 24, _a_) there is another
well-made tower (fig. 12, 4), constructed on a point at the entrance
to the canyon, and below it in a cave are well-preserved walls of a
cliff-dwelling.
[Illustration: FIG. 13.—Ground plan of Horseshoe House.]
A short distance due north of Horseshoe House, at the head of a small
canyon, a tributary of Bridge Canyon, there are two large pueblos and a
round tower. The pueblos are mentioned by Prudden, who gives a ground
plan which indicates an extensive settlement.