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Research


In the broadest sense my research represents a melding of the fields of Quaternary paleoecology and cultural ecology.  While most of my research aims to elucidate various aspects of cultural change, I approach questions of cultural change with a physical sciences (biogeography and Quaternary paleoecology) toolkit.  In the field, my sampling methods range from lake sediment coring to modern vegetation sampling to archaeological test pit excavations.  I believe that this kind of integrative approach yields novel insights into the nexus between nature and culture. 

Holocene Vegetation and Climate Change
   Pollen                                               field working I completed my Ph.D. in December, 2001.  My dissertation was essentially an environmental history of western El Salvador, the most deforested and densely populated country in Latin America.  Human impacts - both before and after the early 16th Century arrival of Europeans - were considered in light of the historical ecology of the region.  The results from environmental reconstructions using pollen, carbon isotopes, magnetic susceptibility, and charcoal data indicate that the prehistoric Maya of El Salvador did have a significant and lingering impact on the local flora, fire regimes and erosion rates.  My dissertation also provides the first evidence of an Early to Middle Holocene (8500-6000 BP) warm period in the highlands of northern Central America, a finding that informs current debates regarding Holocene climatic stability in the Neotropics. Current paleoecology/paleoclimatology projects in Latin America include continuing work in El Salvador, as well as collaborative efforts in Nicaragua (with Mark Abbott, Univ. Pittsburgh) and Mexico (with Andrew Sluyter, LSU).

Volcanic Hazards
    extracting maize macrofossilsIlopango TBJ tephraAnother of my research areas is natural hazards.  Specifically, I am working volcanic hazards and the cultural/historical record of human responses to these events in Central America.  My research shows that the southeastern Maya not only initiated widespread environmental change, but that they were also dramatically affected by environmental perturbations, such as the 5th century Tierra Blanca Joven (TBJ) eruption of the Ilopango caldera in central El Salvador.  Research carried out with colleagues John Southon (UC Irvine) and Payson Sheets (Univ. Colorado) indicates that the economic infrastructure of southern Mesoamerica was irreparably disrupted by the TBJ event, and moreover that the cultural trajectory of the Maya was profoundly influenced by the catastrophe.



Pre-Columbian Agriculture in Latin America
   TazumalMaize leaf impression from I have also been pursuing the study of prehistoric agricultural systems.  The history of maize cultivation has been investigated using both data from lake sediment cores and fossil agricultural fields.  While studying the 5th century Ilopango eruption, colleagues and I discovered that the tephra resulting from this event effectively preserved a 1500 year-old cultural landscape, one containing abundant evidence of prehistoric agriculture in the form of cultivated fields.  We have also discovered similar, but better preserved field vestiges buried under tephra from the ca. 2800 year-old Cuzcátan eruption in the valley of San Salvador.  These fields represent a virtual time capsule of Middle Formative Period southern Maya food production.  One of these fields contains a sophisticated drainage ditch system and abundant maize leaf impressions preserved in situ.  It is my hope that continued diachronic studies of these fossil fields will eventually lead to a better understanding of the relationships between demographic intensification, changing food production strategies, and land-use patterns in Prehispanic Mesoamerica. 
    The stratigraphic pollen record has also been used to track the history of maize in El Salvador.  The ca. 4400 year-old Zea pollen from Laguna Verde in the Sierra de Apaneca is the oldest evidence of maize/teosinte ever discovered in El Salvador. Continued work in this area will hopefully help to situate the history of maize cultivation in El Salvador within larger debates regarding maize origins and its geographical dispersal throughout the Americas.