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 23

Fig. 1 Location map of the
La Playa site in northern
Sonora, Mexico and ASTER
satellite image of the area
surrounding La Playa
extensive modern erosion has exposed artifacts across much of the site surface,
this work focuses on areas where the artifact layer lies below a sediment cap. The
goals of the study are to address whether this artifact layer is a product of (1)
cycles of deposition and erosion whereby artifacts are displaced and concentrated
by fluvial action (environmental), or (2) if the artifact layer represents an undis-
turbed, earlier level of occupation that was subsequently buried by younger
deposits (cultural).
Background
Archaeological Setting
La Playa is a 9 km 2 archaeological site located along the Rio Boquillas, north
of Trincheras in northern Sonora, Mexico (Fig. 1 ). Unprecedented numbers of
archaeological features are complemented by a dense, diverse material culture of
artifacts and human refuse that spans from the terminal Pleistocene to the modern
age (Carpenter et al. 1997 , 2003 , 2005 ; Villalpando et al. 2000 , 2001 , 2002 ,
Fig. 2 ). The earliest evidence of human utilization of La Playa—a few projectile
points—date to the Clovis tradition (13,500-13,000 cal BP) of the Paleoindian
period (14,000-12,000 cal BP). During the Holocene, a continuous sequence of
projectile point styles indicate repeated human use of the site over the approxi-
mately 8,000 year-long Archaic period. With the adoption of horticulture during
the subsequent Early Agricultural period (3,700-1,900 cal BP), the occupation of
La Playa was markedly more intensive. Although artifacts document a relatively
continuous utilization/occupation of the site for the past 12,000 years, the majority
of the cultural materials represent the remains of the extensive Early Agricultural