A Review of the Valsequillo, Mexico Early-Man Valsequillo Archaeological Sites (1962-2004) with Emphasis on the Geological Investigations of Harold E. Malde

Harold E. (Hal) Malde began his study of the geology of the Valsequillo Basin south of the city of Puebla, Mexico in 1964 as a member of the Valsequillo Archaeological Project. Earlier, field reconnaissance by Cynthia Irwin-Williams (Harvard) and Prof. Juan Armenta Camacho (U. Puebla) had located four sites along the north shore of the Valsequillo Reservoir, state of Puebla, where well made stone tools and the remains of extinct Pleistocene mammals occurred together in situ. The artifacts could not be dated directly by 14C since no datable carbon was preserved.

Malde planned to date the archaeological sites indirectly using geological evidence. This included detailed mapping of much of the basin, then essentially a geological unknown, and attempts to match dated tephra layers (volcanic ash and pumice) in the 8-24 kyr range on nearby La Malinche volcano with those that occurred at the sites. No match was ever found.

Meanwhile, uranium-series dates on a mastodon tooth fragment and a butchered camel pelvis from the El Horno and Hueyatlaco sites gave dates of ca 250 - 350 kyr. Additional excavation at Hueyatlaco in 1973 confirmed the stratigraphy originally reported by the Irwin-Williams group. Zircon fission-track dates from two tephra layers stratigraphically above the artifact-bearing units were roughly similar to that for the tooth and bone (Steen-McIntyre et al., 1981, Quat. Res. 16, 1-17; http://www.valsequilloclassic.net/nuke/). The unexpected great age for the samples created a deep rift between the project archaeologist and the geologists. Work was suspended for over two decades.

Research at Hueyatlaco began again in 1997. Hal's last visit to the site was in 2004, when at age 80 he filmed the new excavations, assisted in preparing the trench profile, and entered into lively dialogue with the project scientists.