GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 233-3
Presentation Time: 9:00 AM-6:30 PM


WAHL, David B., U.S. Geological Survey, 345 Middlefield Rd, MS-975, Menlo Park, CA 94025,

Widespread abandonment of several large human population centers in the southern Maya lowlands at the end of the Classic period (~AD 900) has been attributed to environmental change caused by human activity and/or climate variability. Defining the interplay between climate change, human modification of the environment, and cultural responses, however, has been a persistent challenge in the Maya lowlands. Fire histories are a useful tool in parsing drivers of environmental change in this region as fire is linked with pre-Hispanic land use and was essential to anthropogenic landscape modification. When proxies for anthropogenic activity are coupled with independent reconstructions of climate variability, it becomes possible to assess the relative importance and timing of natural versus human drivers of landscape change. We present results of a paleoenvironmental reconstruction from Laguna Ek’Naab, a small closed basin lake in the northern Homul region. A 7-meter-long sediment core extends from ~AD 300 to 2013, providing the opportunity for exceptionally high resolution analyses. Multiple proxies are used to reconstruct fire history, agricultural land use, climate, and environmental conditions, which include pollen, macroscopic charcoal concentrations, stable isotope (C and O) geochemistry, and geophysical properties. Proxy data are integrated with settlement history as inferred from archaeological mapping. Results show high amounts of erosion and local burning in the watershed from around AD 300-700, with peak values between AD 625-700. Zea pollen, which indicates nearby maize agriculture, is consistently present from the base of the core until around AD 1000. Decreased anthropogenic activity in the watershed during the Terminal Classic period, associated with evidence of regional aridity, is indicated by the near-complete absence of burning and decreased erosion from AD 750-850. After AD 850, burning resumes at significantly lower levels and persists until AD 1000. Evidence for fire and landscape disturbance cease after this time, although occasional Zea pollen is found until ~AD 1430, suggesting small human populations persisted in the watershed for several centuries after the end of the Terminal Classic period.