Initial results of an electrical resistivity survey of the volcano-sedimentary sequence of the Valsequillo basin in central Mexico are presented. The volcanosedimentary deposits preserve rich paleontological , paleoclimatic and paleoenvironmental records , which include extinct megafauna remains associated with human artifacts. The report of possible 38 ka old human footprint tracks in the Xalnene tuff attracted renewed interest in the basin stratigraphy. We examine the shallow stratigraphic sequence in the Xalnene tuff outcrop plain northwest of Cerro Toluquilla volcano using vertical resistivity soundings (VES). Inversion models of VES soundings show a layered structure of high and low resistivity units, which characterize the Xalnene tuff , lacustrine and fluvial edements and volcanic rocks. 2-D resistivity cross section document three major units corresponding to the Zalnene tuff and sediments filling a