GRA has undertaken a number of projects at pre-contact quarry sites in the eastern United States. Our investigations have focused on establishing the geomorphic and geologic contexts of quarries and the sourcing of lithic materials used in the manufacture of stone tools by pre-contact peoples.
Our most intensive investigation to date has been at the Marshalls Creek Quarry sites in Northeastern Pennsylvania. This project entailed both extensive field and laboratory investigations. Fieldwork consisted of evaluating whether or not lithic materials identified at sites were stones quarried during pre-contact periods; stratigraphic observations to establish the integrity of quarry sites, and the development of a site formation model for these sites. Fieldwork was undertaken in conjunction with archeologist-led testing excavations by CHRS of North Wales, PA for the PennDOT. The geomorphic investigations employed radiocarbon and optically stimulated luminescence (OSL) dating, as well as studies of soil geochemistry and sedimentology. Extensive laboratory studies of bedrock and quarried material consisted of: analyzing physical properties of the chert to assess their suitability for flint-knapping; thin-section petrography and macroscopic identification of rock fabric by George Pevarnik and Joseph Blondino from Temple University; and instrumental neutron activation analysis (INAA) by the Archaeometry Laboratory at the University of Missouri Research Reactor to characterize source material geochemistry. These laboratory methods were used to successfully develop an Atlas of criteria which can be used for identifying cherts within the region. The final report serves as the baseline for comparing archeological assemblages to geologic Formations in northeastern Pennsylvania, which has relevance for studies of pre-contact settlement patterns and economy.
By taking an interdisciplinary, scientific approach and utilizing researchers from a range of top institutions GRA is capable of conducting a full range of archeological studies which employ targeted geological methods relevant to archeological investigations at quarry sites.