The Use of Innovative Techniques to Decodify Early Anthropic Activity in the Sonoran Desert (NW Mexico)

The Early Agriculture Period (EAP) in the southwest of USA and northwest of Mexico began just after the Altithermal period (7500–4500 years BP). During the EAP, agricultural societies cultivated corn and constructed canals for irrigation; however, searching for the sites of this period and reconstruction of the ancient activities surrounding them meets difficulties and requires the development of geoarchaeological indicators. The present study aims to identify anthropic processes from three paleosols in the arid Northwest Mexico using physical, micromorphological and biogeochemistry characteristics. In addition, the physical and biogeochemical variables were analysed by redundancy analysis. Results show that the combination of physical, micromorphological-micromorphometric and biogeochemistry analyses are an accurate indicator of agriculture during the Early Agriculture Period (4500 years BP); additionally, the soil organic P (Po ) fraction extracted by HCl (HCl-Po ) is also a good indicator of soil changes induced by human fire management. The integrated analyses of these methods thus had a higher potential for determining the human activities effect on paleosols from the Late Holocene.