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 25

Fig. 3 Quickbird satellite image of the La Playa site, denoting the different areas. Satellite image
source: DigitalGlobe
Although artifacts are distributed across much of the site, the majority of the
work at La Playa has concentrated in four areas, subjectively defined by the dis-
tribution of artifact and feature concentrations (Fig. 3 ). The distribution of cultural
materials, however, is largely the result of modern erosional process affecting
the sites' surface; the areas are therefore principally defined by differential patterns
of erosion observed across the site. Three of the areas are characterized by exten-
sive cut-bank and gully erosion that varies in depth by each area (Hornos
Alineados = 0.5 m deep, Los Entierros = 1 m deep, Los Monticulos = 1-4 m
deep). The fourth area (El Canal) is characterized by low energy sheet flood erosion,
which has not eroded deeper than 0.4 m.
Methods
Investigation of the artifact layer at La Playa began with field reconnaissance to
identify those areas at the site where the layer is exposed. These localities are
situated along arroyos where recent flooding has cut into the landscape exposing
a section of the geological and archaeological sequences at the site. A total of 19
locations (Fig. 4 ) were selected to define a detailed vertical stratigraphic section
of the sediments present along with the artifact layer. At each section, GPS
coordinates were recorded to provide the location and elevation control using a
Trimble ProXH GPS unit. Sections were photographed and vertical stratigraphic
profiles measured to document sediment type, grain size, thickness and the
presence of any sedimentary structures that might assist with paleoenvironmental
interpretations.