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Highlights
Geoarcheaology
David L. Cremeens

Geoarchaeology, the application of geoscience techniques and concepts to archaeological studies, provides an earth-surface based context for the archaeological record — providing input as to why people were at a certain location, what they did there and what has happened to their record since they left. Of all the geoscience disciplines covered in this Highlights issue, geoarchaeology may be the least traditional and is certainly one of the most interdisciplinary. Geoarchaeologists come from a wide variety of geoscience backgrounds and practice the discipline in academia, private industry (including cultural resource management firms) and various governmental agencies.

This year, seven topical sessions have been proposed for the annual Geological Society of America (GSA) meeting in Denver. In addition, a pre-meeting field trip, proposed by Rolfe Mandel and Jack Hofman of the University of Kansas, as well as Steve Holen of the Denver Museum of Nature and Science, will visit the High Plains of northwestern Kansas and eastern Colorado to focus on buried Paleo-Indian landscapes and sites. The Society for American Archaeology (SAA) has a Geoarchaeology Interest Group (GIG). At this spring's annual meeting, GIG sponsored one symposium on geoarchaeology and complex societies organized by Mandel and Paul Goldberg of Boston University.

How to become a geoarchaeologist

Formal academic programs for training as a geoarchaeologist are in the early stages. Industrious graduate students in geology, geography, archaeology and anthropology departments have been able to put together graduate programs for years. These individuals were the driving force behind the Graduate Programs Directory. Created in 1996, the directory is currently being updated. The directory is available via links on Web sites of the Archaeological Geology Division of the GSA and the Geoarchaeology Interest Group of the SAA.

Several North American universities offer one or more classes in geoarchaeology, usually at the senior and graduate levels. Graduate programs are slowly beginning to evolve. The University of Arizona has the National Science Foundation "Integrative Graduate Education and Research Traineeship." This five-year grant for graduate training in archaeological sciences is available through any of the participating academic departments. Students would receive their doctorate degree in that discipline. The three major foci of the program are: chronometry, past environments, and ancient materials and technologies.

Field training in geoarchaeology is in an even earlier state than formal academic training. In the summer of 2005, Mandel and E. Arthur Bettis of the University of Iowa will be conducting a joint three-week geoarchaeology field school. The school, open to both graduate and undergraduate students, will focus on natural processes that create the archaeological record and stratigraphic approaches to reconstructing landscapes of the past. One half of the class will take place in the east-central Plains, based in Lawrence, Kan., and the second half will be based out of Iowa City, Iowa, and will focus on the Mississippi River valley, the Des Moines Lobe and the Paleozoic Plateau.

What's new?

Who the earliest inhabitants of the Americas were, and how and when they got there continues to be of prime interest in the geoarchaeology community. A GSA session on the topic last fall as well as two articles in the February 2004 Geotimes highlight the increasing interest in this topic. In the first article, a review of the "Ice-Free Corridor," Lionel Jackson and Michael Wilson provide a history of the development of this model and a good discussion of the geoarchaeology of several key sites that were instrumental in developing it. They end the article with the suggestion that the ice- free corridor may not be the best model for the interpreting the entry of the first peoples into North America.

The second article picks up where the first left off, with Renée Hetherington, J. Vaughn Barrie, Roger MacLeod and Wilson discussing geological evidence for the coastal migration route that followed the northwestern coast of North America. The coastal migration route is along continental plate boundaries and is geologically active with earthquakes and relatively rapid response to eustatic sea level, sedimentation, erosion, glacial and water loading, and tectonic movement. Coastlines may have shifted more than 100 kilometers within the span of a few lifetimes of the migrants. Part of the continuing research is locating paleoshorelines with the idea that many sites are now drowned.

Another area of increasing interest is the application of geoarchaeology to historical and urban archaeology studies. At a session at last year's GSA meeting, several papers discussed research in which geoarchaeology was instrumental in the evaluation of historical sites. Matthew Harris, Joseph Baker, Gary Stinchcomb, Richard Petyk and John Branigan dealt with using comprehensive geoarchaeology techniques to relocate and map farmstead building foundations and other cultural elements in a key portion of the Civil War Battle of Antietam battlefield in Washington and Frederick Counties, Md. Alan Gilbert and Joseph Schuldenrein are organizing most of these papers for publication in an upcoming issue of Historical Archaeology.

One focus at historical sites, particularly battlefields, is the accurate interpretation of geomorphic conditions and topography at the time of interest, and their influence on the outcome of events at the site. At the recent GSA combined Northeast-Southeast regional meetings in Tyson's Corners, Va., two sessions were held on "Geology and the Civil War." Scientists discussed the influence of topography and geology on the various battles, along with changes in the landscape brought about by the battles.

In a paper presented at last year's GSA annual meeting, Philippe Letourneau discussed the challenges facing geoarchaeologists in deciphering natural and cultural stratigraphy in urban historic archaeological sites. The regulatory context of these sites imposes a number of limitations on the geoarchaeologist, including construction schedules, inadequate exposures in active urban areas, and continuing human activities that tend to mix or even destroy past records.

One final note of interest to geoarchaeologists is the continuing refinement of the radiocarbon record (Geotimes, February 2004). In the Jan. 9 Science, an article by Edouard Bard, Frauke Rostek and Guillemette Ménot-Combes describes the problems with radiocarbon dating, particularly on older sites (older than 22,000 calendar years ago) and describe methods to calibrate radiocarbon years to calendar years based on paleoclimatic data from around the world. New results presented by K. Hughen, S. Lehman, J. Southon, J. Overpeck, O. Marchal, C. Herring and J. Turnbull in the same issue has now pushed the calibration curve to at least 41,000 calendar years and maybe as far back as 50,000 calendar years based on a stratigraphic method with ocean sediments.

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Cremeens is chair of the GSA Archaeological Geology section and senior staff soil scientist for GAI Consultants, Inc., in Monroeville, Pa.

Links:

Archaeological Geology Division of the GSA
Geoarchaeology Interest Group of the SAA

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