University of Virginia Library

DROUGHT AND THE BURIED CHANNEL

Bryan first chanced upon this buried watercourse near the southeast
corner of Pueblo del Arroyo without knowing at the time that a
nearby exposure had previously been discovered by W. H. Jackson
(1878, p. 444). At this site, the section 4 of his map, Bryan (1954,
p. 54) described the old channel as 13 feet 5 inches deep and its
gravelly bottom 15 feet below the existing surface. The difference
in the two figures illustrates the fact that, after the 13-foot gully
had been completely refilled, an additional 19 inches of sand and
silt were spread upon the refill. Elsewhere the overburden is thicker
and the gully, deeper. The bottom of it lies 18 feet below the surface
in Test Pit No. 3, on the plain fronting Pueblo Bonito (pl. 7, upper).

A short distance upstream from section 4 and on the opposite
bank, Jackson (ibid., p. 443) in 1877 observed a small ruin whose
foundations were "5 or 6 feet below the general level of the valley."

Fig.24 -The "Far East Trench" (upper); the "Middle Trench"; and
the "East Mound Trench" from the post-Bonito channel to the
foundations of Room 171.

Plate 78

Left: To increase
its height,
stones were piled
loosely upon the
east retaining wall,
East Refuse
Mound.

(Photograph by
O. C. Havens,
1924.)

Right: A makeshift
wall enclosed
the East Refuse
Mound on the
south.

(Photograph by
Neil M. Judd,
1922.)

Plate 79

Left: A partly
razed second-typemasonry
structure
was buried under
village waste, East
Refuse Mound.
North retaining
wall at workman's
elbow.

Right: Four feet
beneath the south
foundation of
Room 171, our extended
East Mound
exploratory trench
bared a broad open
hearth.

(Photographs by
O. C. Havens,
1925.)

Plate 80

Until January 22, 1941, the Braced-up Cliff towered above the
fourth-story wall of Room 14b.

(Photograph by Neil M. Judd, 1926.)

A fourth-type wall between Rooms 55 and 57 was supported upon 2 timbers
their ends inserted into the stonework of Old Bonitian Room 58.

(Photograph by Neil M. Judd, 1922.)

Plate 81

Upper: A supposed multiple shrine, built upon blown sand 3 feet above the east foundation of
Room 176.

(Photograph by Neil M. Judd, 1923.)

Lower: Beams seated in pecked holes roofed this small talus room, west end of the
Braced-up Cliff.

(Photograph by Neil M. Judd, 1927.)

This little P. III house has since been destroyed but beneath it, as
seen in 1920 and later, layered alluvium extended to right and left,
the patient deposits of floodwaters flowing over a grassy plain
(Bryan, 1954, pl. 6, upper). In Chaco Canyon where the gradient
has always been a modest one, summertime floods formerly advanced
slowly and dropped their silty burden on the way.

Bryan traced his buried channel up and down canyon a distance
of approximately 5 miles and recorded his observations at 23 numbered
sites. While so doing he repeatedly found proof of human
occupancy coincident with deposition of the main valley fill. He collected
Pueblo I potsherds as much as 20 feet below the surface, while
those attributable to P. III, the period of Pueblo Bonito and its
contemporaries, rarely occurred below 4 feet. Of known P. I pithouses
in the canyon, two stood with roof levels at a depth of 6 feet
or more (Judd, 1924, p. 403; Roberts, 1929, p. 71; Bryan, 1954,
p. 32).

The fact that water-borne sediments were sometimes laid down
so gently that even charcoal in ancient hearths was not appreciably
disturbed evidences both a low gradient and a long-continuing grasscovered
surface. We did no testing south of the present arroyo, but
on the north side we met floodwater silt layers repeatedly. Although
not always deposited as evenly as those underlying the little P. III
ruin near Bryan's section 4, they are undeniable.

When exploring the Northeast Foundation Complex (fig. 11),
we exposed 22 inches of excellent Late Bonitian masonry at Station 1
upon a sturdy foundation 4 feet 7 inches high (pl. 48, right). At
6 inches deeper, or 7 feet from the present sandy surface, is a pavementlike
sheet of floodwater silt, smooth as a kitchen floor. And
wherever we dug deep enough throughout that whole foundation complex
we came upon the same or a similar silt layer.

Close under "Hillside Ruin" are five quadrangular fireplaces
(pl. 47, lower). A test pit 4 feet 10 inches deep between the second
and third revealed another adobe pavement, floor-smooth but covered
by debris of reconstruction and wind-blown sand. Presumably
that pavement is a continuation of the one we had previously
encountered outside Room 184—the pavement that prompted our
5-foot-wide trench to the lower terrace below the Braced-up Cliff
(pl. 42, left); the same pavement, presumably, as that at a depth of
4 feet outside Room 187 where it is overlain by 20-24 inches of
blown sand.