Quaternary Stratigraphy of the La Playa Archaeological Site (SON F:10:3), Northern Sonora, Mexico - Reconstructing Human-Landscape Interactions: Interpreting Desert and Fluvial Environments - page 6

Fig. 2 Quickbird satellite image of the La Playa site with the major areas of the site labeled.
Satellite image source: DigitalGlobe
remains. Drake ( 1961 ) examined gastropods from the silt, and identified genera
suggesting moist conditions prevailed. This supported Johnson's ( 1960 , 1963 )
proposal that La Playa was a cienega or marsh-like setting prior to rapid incision
and subsequent arroyo formation in the early twentieth century. The exposed
thickness of this silt is approximately 2 m, and it unconformably overlies a red,
sandy paleosol with calcareous root casts. The upper parts of the paleosol occa-
sionally contain imbricated and rounded fluvial gravels. The paleosol also contains
diverse Rancholabrean megafauna including mammoth, bison, camel, horse, deer,
peccary, and tortoise (Carpenter et al. 2005 ). Although the development of the
paleosol dates broadly to the Pleistocene based on the fossil assemblage (Carpenter
et al. 2005 ), its exact age and that of the overlying silt have yet to be determined.
Archaeological Setting
Over 3,000 archaeological features have been recorded and 580 of these have been
excavated during the last 14 years of archaeological investigation at La Playa.
The earliest occupation of the La Playa site was during the Clovis tradition
(13,500-13,000 cal BP) of the Paleoindian period (14,000-12,000 cal BP)
(Fig. 3 ). During the Early Agricultural period (3,700-1,900 cal BP), occupation
and utilization of La Playa intensified and as a result, artifacts and human burials
date primarily to this period. Followed by the Early Ceramic period and Trincheras
traditions, use of La Playa diminished, but a notable presence of humans continued
at this locale until about A.D. 1950.