Magnetic study of archaeological structures in La Campana, Colima, western Mesoamerica

Abstract

Results of a magnetic survey of the archaeological site at La Campana in the Colima area of western Mesoamerica are reported. The site is located in the northern suburbs of the city of Colima over a terrain characterized by volcanic debris avalanche deposits. The study area of about 12,600 m 2 is divided into two sections corresponding to (1) the main archaeological site and to (2) a potential extension north of it. The magnetic survey shows the presence of three large dipolar anomalies oriented N–S or NNE–SSW occurring over small hills some 2 to 4 m high. The archaeological excavations have uncovered three large structures made mainly of rounded volcanic boulders built on large platforms. The southern structure consists of a pyramid (25×25 m 2 at its base) and an adjacent structure (at least 30×15 m 2). The central structure is a pyramid (20×20 m 2) with stair-like accesses on either side. The northern structure is a large complex extending over an area at least 40×30 m 2. A detailed survey in the open plaza area, using the vertical gradient method, revealed an elongated shallow linear feature, which turned out to be part of a channel network constructed with flat volcanic slabs. Inverted conical openings that end in a small well are connected to the channel network, which was apparently designed to collect water from rain and distribute it to the surrounding structures. The magnetic survey also shows the occurrence of a dipolar anomaly over a small topographic elevation that may likely correspond to another large pyramid. North of it, there is a series of elongated anomalies similar in shape and amplitude to those associated with the hydrological network. The archaeological remains extend over an area considerably larger than the one excavated in the archaeological study. The characteristics and size of the pyramidal structures, the plazas and channel network, and the apparent overall extension of the archaeological site strongly suggests that La Campana constituted a major urban and ceremonial center in westernmost Mesoamerica.