AN EARLY ANTHROPOCENE ANALOG: ANCIENT MAYA IMPACTS ON THE EARTH'S SURFACE

The Maya lowlands has been one of the world’s most active regions for archaeological and paleoclimatic research, but there has been too little geomorphic work. We present new, updated, and synthesized research on human impacts across the Maya lowlands in the Yucatán of Mexico, Petén of Guatemala, and Belize. We draw from the larger region but also our own field studies from lake cores, wetland excavations, alluvial fans, and new research on erosion and aggradation. To understand geomorphic and ecological changes, we examine stratigraphy with relative and radiocarbon dating and a host of paleo-environmental proxies from carbon isotopic ratios, elemental analysis, pollen, phytoliths, macro-botanicals, and soil and water chemical analyses. Most depositional environments show human impacts during the Maya period of the last 3 millennia, though this varies in severity and chronology with many surprisingly early impacts from the Preclassic Maya, nearly 3,000 years ago. Many of these repositories have organic, slow deposition or stable soil formation before agriculture and fire diffused over the landscape in the Third Millennium BP. This led in some areas from 3000 to 1000 BP to accelerated soil erosion and deposition of “Maya Clay” layers. We also distinguish human induced from natural changes such as climatic, natural flooding, water-table rise and gypsum precipitation, and volcanic eruptions. Maya farmers responded with soil conservation technologies in many, but not all, areas. After the Maya Terminal Classic c. 1000 BP many landscapes stabilized, again indicated by organic, low deposition rates and steady soil formation. The Late Preclassic around 2000 BP and Late Classic about 1200 BP experienced widespread droughts coupled with intensive human land uses and geomorphic impacts, but intensive climate changes of the Little Ice Ages without intensive human impacts had little effect on regional geomorphology.