Geoarchaeological insights gained from surficial geologic mapping, middle Moche Valley, Peru

Abstract

We present the results of detailed surficial geologic mapping for a 10 km 2 area of alluvial (quebrada) deposits located in the middle Moche Valley of Peru, where archaeological features and deposits provide cross-cutting relationships and numerical age control for late Holocene erosion and deposition associated with El Niñ o. Despite surfaces containing clasts that are heavily pitted and cracked due to salt weathering, archaeological and 14 C dates indicate that most quebrada landforms in the study area are late Holocene in age and may reflect enhanced alluviation associated with increased El Niñ o activity beginning ca. 6000 cal yr B.P. Our study provides criteria for correlative dating of other Holocene landforms in the Moche Valley area but urges caution in long-distance (Ͼ100 km) correlation because of geographic variability in surface weathering. Surficial geologic mapping aided by archaeological age control allows improved understanding of the rates of landscape change important to the development of complex irrigation-based societies in the Peruvian Desert. ᭧

Late Quaternary hydroclimatology of a hyper-arid Andean watershed: Climate change, floods, and hydrologic responses to the El Niño-Southern Oscillation in the Atacama Desert

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