Man and Environment in the Eastern Atacama Desert (Southern Peru): Holocene Climate Changes and Their Impact on Pre-Columbian Cultures

Abstract

Geoarchaeological evidence for Holocene palaeoclimates in the eastern Atacama desert is compiled to reconstruct the palaeoenvironmental history in the Andean foreland. In contrast to earlier assumptions that El Niňo events controlled the environment of pre-Columbian people in the Ica–Nazca region, major hydrological changes, triggered by oscillations of the summer monsoon in the western Andes, concurred with cultural changes.

Loess deposits, phytoliths, and snail shells indicate that during the early and middle Holocene the eastern Atacama desert was a grassland until the third millennium BC. With the aridisation hunter–gatherer people concentrated on favourable sites along the river oases, which were flooded seasonally by reliable rains in the western Andes. During the rise of the Paracas culture the increasing population density went hand in hand with the formation of more complex societies. After ∼200 BC the Nasca displaced the Paracas culture. Approximately four centuries later the aridisation of the region accelerated and the Nasca settlements shifted eastwards into the valleys of the Andean footzone. With even more reduced summer rains in the western Andes, the river oases dried up. Finally, shortly after 600 AD, the Nasca culture collapsed.

A new hydrological oscillation took place after ∼1100 AD. Monsoonal rains reached the Andean foreland again and narrowed the desert to ∼40 km. During the following Late Intermediate Period (LIP), pre-Columbian people re-occupied the eastern Atacama desert until the sixteenth century AD. The Little Ice Age, with its coldest temperatures between the seventeenth and nineteenth centuries AD, was a very dry period in the study area, so that LIP settlements were abandoned and desert conditions reappeared lasting until today.