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FLOODWATERS

He repeatedly calls attention to features that distinguish these
lesser waterways. They were a characteristic of the second cycle of
alluviation, spreading out disjointedly while the main valley fill was
building up. They tend to be round-bottomed wherever confined
laterally, with a crescentic fill of sand, clay, and clayey gravel; they
occur most frequently in midvalley but often reach out on either
side and one actually underlies the south rooms of Pueblo Bonito.
This latter may have been directed in its course by some undisclosed
upcanyon obstacle for it was remarkably persistent. We came upon
it quite unexpectedly during the digging of our extended East and
West Mound trenches (figs. 7, 24, c).

In both exposures the one-time floodway is floored with coarse
sand in which clay streaks, pellets, and gravel lenses occur. But
these water-borne deposits are overlain by quantities of household
sweeping and the discards of constructional activities—sandstone
spalls and chunks of dried adobe mortar bearing the imprints of
building materials. The source of all this wastage was Pueblo Bonito
itself. Some of it had been dumped there early, as witness the lenticular
bed of household sweepings 10 feet below the surface at Station
180, West Mound trench (fig. 7), and the metate fragment at
comparable depth above Station 164 in the second trench, 250 feet
distant (fig. 24, c). Witness, also, the two deep-lying hearths built
on the dry bed of the channel to meet the momentary need of local
picnickers or traders from far countries.

Obviously here was a former channel that had held transient water
from time to time and that had become a common dump-ground for
the village people living nearby. As village rubbish mounted, the
floodwaters were diverted and new courses eroded. I do not pretend
to experience in such matters, but later stream channels certainly
are indicated by the higher, more or less crescentic layers of
jointed clay and silt-streaked sand seen in the East trench between
Stations 55 and 80.

Our Middle Trench (fig. 24, c), an exploratory venture between the
East and West mounds, was neither long enough nor deep enough
to bare the full history of this intermediate section. The laminated

sand and clay to the right of Station 50 clearly mark the bed of a
former watercourse, subsequently filled with debris of demolition
and it is possible the two walls beyond were erected to curb the
outward drift of that debris. The outermost wall is a little higher
and later than the other. But between and below the two is a narrow
channel in which water once flowed, 5 feet below the present
valley floor.

Running water had threatened the earlier wall from the outside
and, presumably to prevent undercutting, a willow mat, its component
rods horizontal, had been suspended against the lower stonework.
But the water continued on its way, leaving clay-streaked
sand and gravel, until one of the local engineers brought it under
control by erecting a wattled wall opposite the mat. Rotted sticks,
apparently juniper, stood here at the time of our excavation, still
thickly coated on both sides with sun-dried mud. Three sandstone
blocks above the laminated silt may have been placed there to provide
footing for the mason who built the second wall. Outside this
latter, filling what appears to be an old arroyo bed, is a succession
of sandy-clay, gravel, rocks, and water-washed village debris.

Our two major trenches likewise revealed evidence that Pueblo
Bonito farmers undertook at times to harness midsummer floodwaters
and turn them to advantage. A channel on which man clearly exerted
a directing influence appears above Station 60 in the West Mound
trench (fig. 7). The bottom of it, gouged through occupational debris
filling an earlier and broader watercourse, lies 6 or 7 feet below the
present level of the plain and is marked by a quantity of broken
rock purposely thrown there. Above the rock is a 2-foot-thick deposit
of cross-bedded sand and, above the latter, a wide crescent of
laminated sandy clay. While this second layer was collecting, a
masonry wall was built along the south side of the channel.

Shortly thereafter, as I read the record, this masonry wall toppled
outward and was lost under the continuing clay layer before a less
vigorous stream carved a shallower course outside the first and a
bit higher. To restrain this successor, or perhaps merely to check the
spread of household waste, a second and less stable wall was hurriedly
erected (above Sta. 35). Beyond this second barrier, to the
right of Station 10, are the ill-defined limits of Bryan's post-Bonito
arroyo which, in Test Pit No. 3, measured 18 feet 3 inches deep—
well below the channels described above.

What may be a continuation of this same walled waterway was
disclosed in the East Mound trench between Stations 20 and 35

(fig. 24, c), its silt-streaked bottom 4 or 5 feet below the present level
of the plain and its margin again eroded by the post-Bonito, or thirdcycle,
channel.

Bryan (1954, p. 45) believed these successive channels were entirely
artificial because they paralleled the south side of the two
refuse mounds, were confined on the downhill slope by masonry, and
were repaired or replaced whenever a section filled up or washed
out. He believed they were designed to convey upcanyon floodwaters
to fields beyond the village—a practice followed by the inhabitants
of Peñasco Blanco and Kinbiniyol (Judd, 1954, p. 59). That floodwaters
continued to flow this way despite Bonitian efforts to turn
them aside is obvious from the layers of laminated sand and silt they
laid down in passing. That they persisted in their accustomed course
long after Pueblo Bonito had been vacated is further suggested by
the water-borne gravels Dodge (in Pepper, 1920, p. 24) observed in
some of the south-side rooms.

Thus a new and pertinent chapter in the history of Pueblo Bonito
has been disclosed by these prehistoric floodways, rubbish-filled and
forgotten until bared by our exploratory trenches. It is noteworthy
that the south wall of the pueblo, its foundation 2-2½ feet above the
present level of the plain, rests upon a 10-foot-deep rubbish fill the
beginnings of which lie 8-8½ feet below that same plain level (fig. 7).
As the village continued to increase in population and ground area
its accumulating refuse piled up 18 and 20 feet, forcing westwardflowing
floodwaters farther and farther toward midvalley until they
converged to form Bryan's 12th century arroyo.

How long floodwaters had followed this east-west course where
Pueblo Bonito now stands is still open to conjecture. Our geologists
would venture no opinion. We did not attempt to dig deeper than the
floor of our two trenches and this appears to be as deep as Dodge
(in Pepper, 1920, p. 24) ventured. However, John Wetherill during
a visit to Pueblo Bonito on November 2, 1929, told me that his
brother, Richard, had dug a hole 43 feet deep between the ruin and the
south refuse mounds before finding clean sand.

East of Pueblo Bonito, 400 feet beyond Room 176, a shallow
trench exposed still another round-bottomed channel (figs. 11, 24, c).
Its presence adds weight to Bryan's belief that upcanyon runoff, including
that from the rincon back of Chettro Kettle, was sometimes
purposely directed past Pueblo Bonito to down-valley plantings. I
am loath to suggest that the long, lone foundation wall from
Room 176 to Station 2, or that the curved pair south of it, had anything

to do with directing or diverting those floodwaters but it is
possible.