Geoarchaeological evidence from desert loess in the nazca-palpa region, southern Peru:: Palaeoenvironmental changes and their impact on pre-columbian cultures

The paper presents proxies from an interdisciplinary geoarchaeological working group. Sediment analyses and geomorphological studies, radiocarbon ages of snail shells and luminescence dating of loess allow a preliminary chronology of the environmental evolution of the eastern Atacama desert, Nazca-Palpa region (southern Peru). Until now, typical desert loess was unknown from the arid western flank of the Andes (southern Peru). The loess points to periods of more humid conditions with open grasslands at the eastern Atacama desert margin in the early and middle Holocene. In the footzone of the Andes, aridification set in before the Paracas Culture (c. 800-200 BC) evolved, but the Cordillera Occidental remained semi-arid. A second push of increasing aridity started at the latest in the Middle Nazca Period (after AD 250). During this time, the Nazca settlement centres moved upstream through the river oasis, following the eastward-shifting desert margin. It is possible that culminating aridity after AD 600 caused the collapse of the Nazca civilization. During the Gate Intermediate Period (AD 1000-1400); more humid conditions favoured the massive reoccupation of the eastern Atacama up to a distance of about 40 km from the Pacific coast. Since the 14th and 15th centuries, the Palpa region has again been part of the hyper-arid Atacama. The study shows that in the Nazca-Ica region, the deep cultural changes of Pre-Columbian civilizations were not caused by catastrophic run-off of El Nino events, but by a shifting eastern desert margin due to the changing monsoonal influence.