Late Holocene environmental dynamics in fluvial and aeolian depositional settings: Archaeological record variability at the lower basin of the Colorado river (Argentina)

This paper deals with the way in which the environmental dynamics that took place in the lower basin of the Colorado River (Buenos Aires province, Argentina) have affected the degree of archaeological resolution, integrity, and site preservation in different sectors of the study area (e.g., coastal fringe, delta and interior dune fields). Evidence from geomorphologic, stratigraphic, and sedimentary analyses as well as chemical parameters and zooarchaeological assemblages are used in order to propose spatial and temporal variations in the structure of the archaeological record. These lines of evidence were also used for inferring general paleoclimatic trends. The results obtained indicate that the inland landforms that contained Initial Late Holocene archaeological assemblages (3000–1000 14C BP) have suffered important morphodynamic processes that produced site destruction, loss of organic material and lower degrees of integrity and site resolution. Conversely, landforms located near the delta and the coastal fringe underwent more stable geomorphic processes (e.g., pedogenesis) that promoted better preservation, resolution, and integrity during the Initial Late Holocene and, particularly, during the Final Late Holocene (1000–250 14C BP). The recognition of this pattern is crucial in order to evaluate demographic processes linked with the intensity and mode of hunter-gatherer occupation of the area and population dynamics throughout time.