Lisa Wells

"Humans change the land, and the land changes humans." Richard Rothaus made this statement during the American Association for the Advancement of Science 2000 annual meeting, describing the puzzle geoarchaeologists try to understand. We use geologic tools to answer archaeological questions, and we use archaeological data to understand how humans change their environment. Geoarchaeologists come from the ranks of Quaternary geologists, geomorphologists, geographers, sedimentologists, stratigraphers and archaeologists. Our research crosses the broad divide that separates the physical sciences from the social sciences. As such, we have been doing — since before the beginning of the 20th century — the research that Gail Ashley, Geological Society of America past president, recently termed "new science" (GSA Today, v. 10, p. 24, 2000). Rapp and Hill (Geoarchaeology: The Earth Science Approach to Archaeological Interpretation, Yale University Press, 1998) provide a good historical review.

People as earth-movers

Humans today move more sediment than does any geologic process. The engineering literature of very short period human-induced perturbations is strong, but our understanding of sustained and intense land use is poor. As we come to terms with the rapid depletion of the natural resources of the earth surface (soil, biota and sediment), geoarchaeologists can document how both geology and culture responded to past failures at land conservation. The importance of this topic is documented in increased numbers of papers, presentations and symposia, including the 1999 Geological Society of America annual meetings, the 2000 meeting of AAAS, the 2000 meeting of the Society for American Archaeology and the American Quaternary Association special report, "A Vision for Quaternary Science and Geomorphology."

The field matures

Through much of the 1970s and 1980s geoarchaeological projects generally were tacked on to archaeological projects. Scientists worked in parallel toward an understanding of geomorphic and cultural change. The language differences between the physical and human sciences reinforced the divide, and each discipline’s reports on a region were in effect separate reports. Many archaeologists appreciated the need to include a project geoarchaeologist, but they did not know how to integrate geoarchaeology research into their results. In my early collaborations, questions were often limited to provenance and geochronologic issues. Happily, the situation is changing.

The most exciting trend in geoarchaeology today is that geologists and archaeologists are working together from the conceptual stages of a project so that interdisciplinary questions can be answered. This interaction has required learning each others’ languages — a trend reflected in a wave of recent books that present geological fundamentals to the practicing archaeologist. The complementary books, those that teach archaeological fundamentals to geologists, have yet to appear.

When projects are conceived of and managed with an interdisciplinary staff, data collection and management can be maximized to answer interdisciplinary questions. For example: How have some cultures sustained agriculture and grazing for long periods while others have suffered catastrophic failures of their soil and ecosystems? What specific kinds of effects can a landscape sustain for millennia without failing? How long does it take for the soil and ecosystem to recover from collapse? What are the feedbacks between natural systems and the cultural systems that must adapt to environmental change? How do landscape and culture coevolve? Recent technological advances in desktop geographic information system and database software, digital photography and geographic positioning system surveying greatly aid this research. Answering these questions is crucial if we are to learn from the past and avoid repeating past environmental tragedies.

Can we live within our means?

The extent and intensity of current land use may well be approaching the earth's carrying capacity. Given the threshold nature of geomorphic response, we may exceed carrying capacity before we are aware of it. My own research in Peru, Greece, Cyprus and the western United States suggests that humans repeatedly have had to relearn these lessons, forever battling to keep the soil on the fields. (Perhaps we should heed an ancient Cypriot proverb: "The fool adds manure, the wise man builds check dams.") We may need to turn our attention away from soil amendment, pest management and genetic engineering of crops toward soil conservation. Geoarchaeology has the potential to help us avoid relearning these lessons the hard way in the 21st century.
 

Wells is the chair of the Archaeological Geology Division of the Geological Society of America and teaches geology at Vanderbilt University.  E-mail: lisa.e.wells@Vanderbilt.edu

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