A sediment core collected in 1993 from Lake Chichancanab, Yucatan, Mexico, contained evidence of a protracted drought that coincided with the Classic Maya collapse in the 9th century A.D. Cores retrieved from Lake Chichancanab in summer 2000 are better dated and have higher sedimentation rates, providing new, higher-resolution records of climatic events in northern Yucatan. We have also extended our paleoclimate studies into the Peten Lake District, Guatemala, permitting comparison of long-term climate change between the northern and southern Maya lowlands. Preliminary results from Lago Salpeten, Guatemala, indicate that oxygen isotope values were lowest and lake levels were highest during the Preclassic Period, from ~400 B.C. to 150 A.D. Climatic drying, indicated by increasing oxygen isotope ratios, occurred in steps at approximately 150, 560, 850 and 1400 A.D. Several of these events correlate temporally with documented cli-mate changes in northern Yucatan, and with discontinuities in Maya cultural evolution. We used seismic profiling in Lago Salpeten to map the 3-dimensional distribution of the "Maya Clay" unit, an erosional deposit that has been equated with human-induced deforestation of the lake catch-ment. The base of the "Maya Clay" was dated by AMS-14C of terrestrial organic material to 3,160 14C years B.P. (~1400 BC), suggesting that the Peten environment had already sustained substantial Maya impact by the end of the early Preclassic Period. Lastly, two distinct volcanic ash layers were identified in Peten cores and dated by AMS-14C to ~1500 (+/-50) and 1840 (+/-80) 14C yrs B.P.
Hodell, D., Rosenmeier, M., Brenner, M., Curtis, J., Anselmetti, F., Ariztegui, D., McKenzie J. and Guilderson, T. 2001. Human-Climate-Environment Interactions in the Maya Lowlands. Presented at the 21st Symposium in Plant Biology, Lowland Maya Area: Three Millennia at the Human-Wildland Interface, University of California, Riverside, CA, January 18-20, 2001.