THE SOILS AND PALEOSOLS OF AGUADA FENIX AND OTHER ANCIENT MONUMENTS OF THE USUMACINTA RIVER LOWLANDS OF TABASCO, MEXICO

The Maya and Olmec regions of Tabasco, Mexico and greater Mesoamerica provide a vast landscape to study the soil Anthropocene by analyzing soils below, within, and above well dated and often thick ancient construction. Recent archaeological rediscoveries from wide area Lidar surveys (Nature 2020) showed features that we subsequently learned included the largest (3.2 to 4.3 million m³) and earliest (~ 3200 BP) Maya structures based on extensive excavations and 69 radiocarbon dates with Bayesian modeling. The ancient Maya built these platforms from multiple sediment sources from wetlands, floodplains, and terraces with distinctive colors and chemistry. This paper uses excavations through multiple meters of ancient infrastructure at Aguada Fenix and other nearby sites along the Usumacinta River in Tabasco, Mexico’s coastal plain to compare soil genesis over time. The Bayesian statistical model provides a precise chronology, and we characterize the soils with standard soil analyses including LOI, XRF, XRD, ICPAES, PSA, and other techniques. We present change over depth in soil profiles of elements, minerals, SOM, carbon isotopes, and soil morphology and types, as well as soil ages and soil parent materials. The excavations reveal soils formed before and after ~ 3200 years ago, and include buried Oxisols and Vertisols in older parent materials and Mollisols formed in more recent parent materials. We present models of diachronic soil changes and for sourcing the disparate sediment sources the ancient builders used to create these features.