Quebrada Tacahuay, southern Peru: A Late Pleistocene site preserved by a debris flow

Here we describe the properties of a debris flow apparently generated by a warm phase El Niño event that buried an intermittently occupied Late Pleistocene forager site located in the southern coastal desert of Peru. Although the event deposited roughly one meter of sediment over the initial occupation, our analyses of debris flow dynamics and data from large scale archaeological investigations indicate that the earliest anthropogenic deposits at the site of Quebrada Tacahuay were preserved intact as a result of the burial episode; there is no evidence that the debris flow scoured or disturbed the cultural deposits. The event that buried the oldest archaeological contexts at Quebrada Tacahuay differs from other flood events that are characterized by turbulent, fast-moving floodwaters. Our data on debris flow dynamics and our results from excavation have implications for identifying, investigating, and interpreting other deeply buried archaeological sites both in the central Andes and in other geographic regions.