In search for early peopling evidence: archaeological survey in the upper Quequén Grande River basin (Pampas region, Argentina)

Despite a notable increase in recent decades of archaeological knowledge from the southeastern Pampas, there is little information for the late Pleistocene-Early Holocene period. The current archaeological information comes mostly from rockshelters located in the eastern portion of the Tandilia Range, dating from ca. 11,000 and 10,000 years 14C AP. To expand the archaeological information for this early time period, we have been conducting surveys since 2012 in the upper Quequén Grande River basin, located in the southeast of the Inter Hills plains. The headwaters of this river are in the Tandilia Range; and, after traveling more than 170 km through the plains, it flows into the Atlantic Ocean. Given the proximity to important sources of rocks suitable for tools manufacture, the upper Quequén Grande River basin could have constituted an important circulation route for human groups. Thus far, surveys carried out along the margins of different streams that integrate this basin have only allowed the detection of isolated finds and small concentrations of surface lithic material. On the other hand, the survey along a small hill of the Tandilia Range, resulted in the discovery of a rockshelter with an early chronology archaeological deposit, called La Tinta Rockshelter. Two 20 x 20 cm test-pits were dug to a depth of 65 cm in the rockshelter. At the lower levels, lithic artifacts and charcoal fragments were recovered, one of which allowed obtaining a radiocarbon date. Lithic artifacts, charcoal, and ceramics were recovered in the upper levels, which indicates the reoccupation of the rockshelter during the late Holocene. In addition, rock paintings were identified on the walls. The La Tinta Rockshelter coincides with the greater abundance of sites with early chronologies in the Tandilia Range, attributed by some researchers to a strong dependence of lithic raw material by early populations. However, the absence or low representation of stratigraphic units from the late Pleistocene-Early Holocene in the surveys carried along the margins of the streams that cross the plains, could be conditioning the archaeological signal of this chronological moment. In conclusion, there appear to be an unequal archaeological representation of early sites in the landscape, a result not only of human decisions, but also of a geoarchaeological bias.