GROUND-PENETRATING RADAR IDENTIFICATION AND CHARACTERIZATION OF AN EARLY MONUMENTAL STRUCTURE, NORTH COAST, PERU

The Los Morteros archaeological site is located near the town of Chao on the desert coast of Peru, approximately 475 km north of the capital city of Lima. The roughly elliptical feature (250 meters x 200 meters in diameter and 14 meters high) has a distinct, north-facing central depression and a broad raised area below and adjacent to the mound to the south. The feature occupies a prominent position on a paleoshoreline 5 km from the modern beach. Early archaeological work limited to excavations at the top of the feature identified the site as a Pre-Ceramic Period occupation (3600- 5500 cal BP) focused on maritime subsistence. The original investigator believed the site was built on the top of a relict dune or a sand-covered bedrock hill. A preliminary ground-penetrating radar (GPR) survey in 2006 produced profiles with returns consistent with walls and other architectural features, suggesting that the site is a human-constructed mound. The early Pre-Ceramic dates in the upper portion of the mound suggest that the interior structure may be significantly older. A more detailed GPR survey of the site in 2010, consisting of 25 km of profiles, was used to characterize the interior structure of the mound. This work has identified a series of platforms, large dividing walls creating three distinct, confined areas, smaller buildings, and potential evidence of remodeling or phased construction. This work provides insight into the architectural plan of the site and is serving as the basis for excavations, scheduled to take place from September to December 2012.