Exploring the Durable Effects of Climate and Anthropogenic Factors in Ancient Wetlands

Authors: Byron Smith*, Department of Geography and the Environment, Tim Beach, University of Texas at Austin, Sheryl Luzzadder-Beach, University of Texas at Austin
Topics: Soils, Remote Sensing, Physical Geography
Keywords: LiDAR, Soil, Archaeology, Geochemistry
Session Type: Virtual Paper
Day: 4/11/2021
Start / End Time: 11:10 AM / 12:25 PM
Room: Virtual 36
Presentation File: No File Uploaded

This paper uses LiDAR and geochemical analysis to compare two distinct wetlands along Rio Bravo floodplain of northwest Belize. We focus on a saturated lower basin and compare it to a seasonally saturated upper basin. Our interests center on how these soils developed over time and how those distinct geochemical environments affected human use along this floodplain. Here we present preliminary analysis of remote sensing data and compare it to soil evidence from excavations and cores near the ancient Maya settlements of Gran Cacao and Chawak But’o’ob that reveals soils buried underneath ancient architecture. What makes these regions significant is their history of wetland field cultivation and geochemical divergence. To characterize floodplain stratigraphy, we analyzed particle size distributions to determine soil texture; X-Ray Fluorescence (XRF) to quantify the soil’s elemental composition; loss on ignition (LOI) to measure for the presence of organics and carbonates; carbon isotopes to estimate relative amounts of C4 and C3 species; magnetic susceptibility to estimate ferric iron (Fe) inputs; and accelerated mass spectroscopy (AMS) for chronology. The resulting investigation uncovered depositional sequences in both regions with paleosols of varying ages that extend as far back as 2,340 BP. Our findings also indicate differential sedimentation rates along the floodplain that likely reflect environmental and land use contributions. Together, these data allow us to compare geochemical and anthropogenic factors of soil formation within zones of ancient, intensive, indigenous cultivation.

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