Genesis of an Artifact Layer: Natural and Cultural Processes at the La Playa Archaeological Site, Sonora, Mexico - Reconstructing Human-Landscape Interactions: Interpreting Desert and Fluvial Environments - page 30

Fig. 7 a Photograph of a
section illustrating the
stratigraphic arrangement of
the La Playa silt, overlying
artifact and sandy silt cap.
Note the distinctive
differences in bedding style
between the La Playa silt and
the overlying sandy silt.
b Part of the exposed artifact
layer showing the
concentration of fire-cracked
rock
finer-grained material. This is suggested from the occurrence of mixed artifacts of
Early Agricultural and Trincheras period occupations—spanning almost
2,000 years of occupation at the site. A specific example of this is the occurrence
of human skeletal remains seemingly within the artifact layer mixed with
Trincheras period ceramics. The skeletal remains were radiocarbon dated at
2,816 ± 40 cal BP which dates to the San Pedro phase of the Early Agricultural
period. Considering that the earliest introduction of ceramics in the area is circa
A.D. 150 at the earliest, the coincidence of the skeletal remains in the same
stratigraphic level as the pottery would support the idea that the artifact layer is
comingled materials from multiple occupation events. The interpretation of this
observation is that the San Pedro phase skeletal remains were buried at a deeper
level and the sediment was eroded to the level where Trincheras period occupation
and artifacts were littered among an exposed Early Agricultural period burial.
Such deposits that contain mixed artifacts from multiple occupations are referred
by Bailey ( 2007 ) as a cumulative palimpsest.