Lessons from the mud, lessons from the Maya: Paleoecological records of the Tierra Blanca Joven eruption

Stratigraphic studies of lake sediments were carried out in the Rio Paz Valley and Sierra de Apaneca of western El Salvador. Pollen, charcoal, and organic matter content of the sediments record the Holocene environmental history of the region. Reported here are records from four lake sites, Lagunas Cuzcachapa, El Trapiche, Llano, and Verde. All sites sampled in this region contain tephra from the Tierra Blanca Joven (TBJ) eruption of Volcan Ilopango, a major explosive event that occurred at ca. A.D. 430. This ubiquitous stratigraphic marker allows cross correlation of environmental conditions and human land use throughout the region before and after the eruption. Before the TBJ eruption, most of the study area was under cultivation by Preclassic and Early Classic period farmers; pollen from Zea mays (maize) and agricultural weeds are prominent components of the pollen assemblages from ca. 2000 B.C. until the A.D. 430 eruption. The post-eruption data record fl ooding and increased erosion, as well as secondary forest succession. Abandonment by human populations is clearly indicated in two of the three pollen records (Laguna Cuzcachapa and Laguna Verde), but data from the third pollen site (Laguna Llano) are inconclusive.