Geology Department Colloquium, Apr 22

Speaker: Peter Douglas (’05), California Institute of Technology

Title: “What molecules in mud tell us about the ancient Maya”

Please join us: Tuesday, April 22nd @ 11AM in Edmunds 130

Abstract: The ancient Maya of southeastern Mexico and northern Central America created a highly complex Pre-Columbian civilization, and were also a major cause of regional environmental change. Around 800 A.D. the ancient Maya experienced a major demographic and political collapse whose cause still remains uncertain. Recently, paleoclimate records have suggested that a series of major droughts could have caused societal disruption at this time, but the available data is not fully consistent with archaeological evidence.

I will be presenting new data on interactions between the Maya and their environment gathered from the isotopic composition of plant wax biomarkers preserved in lake sediments. Plant wax hydrogen isotope ratios provide a record of past aridity, while plant wax carbon isotope ratios indicate changes in vegetation related to ancient Maya land use. Additionally, the measurement of radiocarbon in plant waxes is critical to determine the chronology of these environmental records, and also indicates changes in soil carbon cycling. Together these isotopic data suggest that the ancient Maya modified their agricultural practices in response to earlier droughts, but that these adaptations could not mitigate more intense and widespread droughts beginning around 800 A.D.