Eelskin Rockshelter Lithic Debitage Analysis

My name is Alaina Helm, I am a Junior at Oberlin College in Ohio and a Keystone intern in Archaeology for this summer.  Over the past several weeks and for a brief month-long stint back in January, I have been working on a flake refitting project here in The State Museum of Pennsylvania,  Section of Archaeology. The project was supervised by Dr. Kurt Carr, Senior Curator, and  consists of an argillite debitage cluster collected from the Eelskin Rockshelter (36Bu59) that was theorized to have been created over a single knapping event.

Steve Nissly flint knapping

                Analysis began with the organization and cleaning of the entire assemblage of debitage. Artifacts were cleaned using warm soapy water and a Sonicor ultrasonic cleaner, similar to a jewelry cleaner. We also experimented with the use of diluted vinegar water to remove patination, but it was found to be no more effective so was not done on all pieces. Once cleaned, flakes were uniformly laid out on trays for refitting by type as entire, proximal, medial, or distal pieces. A small quantity of other materials was found amongst the debitage and separated out that includes jasper, quartz, bone, and chert. A wide range of colors was noted in the argillite which is generally black. We also found two biface fragments, a proximal utilized flake, and an end scraper among the debitage.

 Several weeks were spent attempting to fit pieces together where flakes had come off each other or flakes had broken apart.  If successful, refitting a flake cluster back together would allow for the study of stone tool creation through flake reduction techniques. In the case of this cluster from the Eelskin Rock Shelter, only five refits were found over several weeks of searching through the hundreds of pieces in the collection. Methods used in attempting to match related flakes together included; grouping by color, grouping by texture, and grouping by type. Type attributes included the shape of the bulb of percussion (Lipped, bulbar, etc.) and the shape/ size of flake (length, width, thickness). These groupings did not reveal the relatively large number of matches that could be expected in a chipping cluster.

The majority of the debitage demonstrates late stage and baton reduction techniques. Late stage reduction is the process of reducing an already acquired raw material into a complete tool. Almost all flakes are thin with several dorsal flake scars. 68.4% of the proximal or entire flakes are lipped. Lipped flakes are a key indicator of late stage baton production technologies. 

Due to the small quantity of matched pieces found and the variations in color and texture, there is a good chance that although the lithic material first appeared to belong to a single chipping event, it instead represents several knapping events. This conclusion is additionally supported by the fact that there is a small amount of lithic materials other than argillite present, as listed above.  Other potential explanations for the high quantity of debitage found together could include that the materials were part of a rubbish pile or that several short knapping events occurred in the same location.               

example of color variation

This comparative analysis was an exercise well suited for my studies, as it brought together my interests in archaeology and geology. It provided useful experience in lithic analysis, and although sometimes tedious and frustrating when days were spent with no matched flakes found, was valuable in determining that the lithics cluster found at the Eelskin Rockshelter was not the refuse of a single toolmaking event. This project was ultimately beneficial to my own learning while also letting us learn a little about the activities being performed on the site.

Thanks for reading my blog and I hope you will check back for another blog post from me about the experimental archaeology test I conducted on stone scrapers.

Bibliography

Justice, Noel D.

1987       Stone Age Spear and Arrow Points of the Midcontinental and Eastern United States. Indiana University Press.

Anonymous

n.d. Eelskin Rockshelter-36Bu159, anonymous manuscript housed in the County Files, The State Museum of Pennsylvania, Section of Archaeology, Pennsylvania Historical and Museum Commission, Harrisburg Pennsylvania.

For more information, visit PAarchaeology.state.pa.us or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .