Geophysical study of a pre-Hispanic lakeshore settlement, Chiconahuapan Lake, Mexico

Abstract

Results of a combined geophysical survey carried out a long the northern shore of Lake Chiconahuapan in central Mexico are presented. The site contains a series of mounds found between the lakeshore and the ceremonial centre named La Campana-Tepozoco Hill. Those features are the remains of habitation complexes built by the lake residents about 1100 years ago. Archaeological excavations performed towards the northeastern margins of the lake uncovered rectangular clusters of basaltic rocks forming the foundations of ancient dwellings, surrounded bya barrier ('bordo'), built to prevent floods. A mound located close to the ceremonial centre was studied using the vertical magnetic gradient (VMG), ground-penetratingradar (GPR) andelectric tomography (ET) methods. Interesting magnetic anomalies were found towards the central portion of the mound and one of these was modelled with a three-dimensional magnetic polygon. The GPR studies unveiled a circular feature in the central portion of the mound that could be associated with abordo. A rectangular structure was also interpreted within the limits of that structure, which is probably the location of ancient dwelling foundations. Electric tomography profiles were collected in the area, around theVMG anomaly. The resistivity model computed shows the presence of a high-resistivity layer, which displays discontinuities within the area defined by the bordo. Presumably, the ancient settlers built their constructions on top of this horizon. The geophysical results reveal a rather complex habitat within the mound. The larger size of the bordo (ca. 30 m in diameter) compared with others already studied by archaeologists makes us believe that the purpose of the site was of administrative use or hosted a wealthy group of people. Dwelling foundations are found within the limits of the barrier. © 2009 John Wiley & Sons, Ltd.