T he northern Petén of Guatemala is one of the more remote areas in the Maya Low- lands. Its intense dry season, lack of peren- nial water sources, and extensive seasonal wetlands form a formidable barrier to settlement. Yet the area was densely populated in the Middle and Late Preclassic periods (1000 B.C.– A.D. 250) and mod- estly occupied in the Late Classic (A.D. 600–900). The prehistoric Maya lived in large urban centers, erected monumental architecture, and exploited the land for its resources. Evidence of such large pop- ulations has led researchers to examine the possi- ble role of environmental change in shaping regional cultural events. Abandonment of the area, which occurred on at least two occasions (ca. A.D. 150 and A.D. 840), has been a puzzle to archaeol- ogists for many years. One possible explanation is climate change (Curtis et al. 1996; Hodell et al. 1995, 2005); another is human-induced environ- mental change in the form of forest clearance and soil erosion (Binford et al. 1987; Deevey et al. 1979; Dunning et al. 2002; Hansen et al. 2002). Theoretically, the fossil pollen record should provide one means of resolving this issue, but in practice it is not always possible to distinguish between naturally and culturally induced environ- A PALEOCECOLOGICAL RECORD FROM A LATE CLASSIC MAYA RESERVOIR IN THE NORTH PETÉN David Wahl, Thomas Schreiner, Roger Byrne, and Richard Hansen Aguada Zacatal is a reservoir located within a bajo 4 km west of Nakbe, Petén, Guatemala. It is 100 m in diameter and the surrounding berm is approximately 1 m tall. The small Classic period site of Zacatal is adjacent to the aguada. The reser- voir’s artificial lining prevents dry season desiccation and enhances microfossil preservation. In 1998 a 335 cm sediment core was taken from the center of the reservoir and analyzed for pollen, microscopic charcoal, and total organic matter. Core chronology, based on two AMS radiocarbon determinations, shows the record covers the period from A.D. 695 to pre- sent. Only the upper 113 cm contained well-preserved microfossils. The pollen record clearly documents a period of agri- cultural activity followed by abandonment and forest succession. In the agricultural period (A.D. 695–840), corn pollen is found in conjunction with disturbance indicators. After the abandonment at approximately A.D. 840, the record is domi- nated by aquatic pollen types and corn pollen is absent. This shift in pollen spectra represents the end of the Classic period. La reserva de agua artificial de Aguada Zacatal está localizada a 4 km al oeste de Nakbe, Petén, Guatemala, en un bajo. Tiene 100 m de diámetro y la berma que la rodea posee aproximadamente 1 m de alto, localizándose cerca del pequeño sitio arque- ológico homónimo del período Clásico. Esta reserva se emplea en las estación seca y permite la preservación de microfósiles. Un núcleo de sedimentos de 335 cm fue extraído de su centro en abril de 1998; y analizado en búsqueda de polen, carbón microscópico, y contenido orgánico. La cronología obtenida en el núcleo sedimentario cubre desde 695 d.C. hasta el presente, sobre la base de dos dataciones en AMS. Sólo los 113 cm superiores del núcleo contienen microfósiles bien preservados. El registro polínico revela claramente la existencia de un período de actividad agrícola y su posterior abandono, sucediéndolo evidencia de bosque. En el período agrícola (695–840 d.C.), el polen de maíz se registra conjuntamente con indicadores de perturbaciones del terreno. Tras el abandono del área, alrededor del año 840 d.C., el registro está dominado por polen de plantas acuáticas, mientras que el de maíz es ausente. Este cambio en el registro polínico representa el fin del período Clásico. David Wahl ■ United States Geological Survey, 345 Middlefield Rd., MS-975, Menlo Park, CA 94025 (dwahl@usgs.gov) Thomas Schreiner ■ Archaeological Research Facility, University of California, Berkeley, CA 94702-4740 Roger Byrne ■ Department of Geography, University of California, Berkeley, CA 94702-4740 (dwahl@usgs.gov) Richard Hansen ■ American Indian Studies Program, Department of Anthropology, Idaho State University, Campus Box 8005 Pocatello ID, 83209-8005 Latin American Antiquity, 18(2), 2007, pp. 212–222 Copyright © 2007 by the Society for American Archaeology 212 LAQ18(2) Wahl 6/8/07 4:00 PM Page 212