Artifact Highlight: A knapped glass base in Bullitt County, KY

By Xiong Xiong , Archaeologist

*All photos were taken by author and permitted for use in this blog post, courtesy of ERG, LLC.

Glass fragments can be a common artifact found at historic sites. Full bottles, bases, body fragments, neck, and lip are some of the pieces that archaeologists come across often. Sometimes fragments contain embossed writing, faded enamel labels, or even a maker’s mark to identify its manufacturer and the date and location where it was made. Other times, glass fragments recovered from a site are small and indeterminate in form and function. The photos below illustrate these common glass finds from a 2018 excavation of site 15BU662 in Bullitt county, Kentucky. This was a multi-component site, meaning it contained both historic and prehistoric artifacts.  A total of 313 artifacts were recovered; 303 historic artifacts and 10 prehistoric artifacts.

Of the 142 historic glass artifacts recovered, the glass base (artifact H) being highlighted here stands out. At first glance, it looks like a thick base of a worn aqua blue container with a maker’s mark. The “KY. G.W.” mark indicates the glass container was manufactured by the Kentucky Glass Works Company in Louisville, which operated from 1879-1887. More detail about the Kentucky Glass Works Company and its manufacturing lifespan can found at

A closer examination reveals that some parts of the base edge has been worked. Glass tends to break clean and relatively straight, yet there are two distinct edges that have small chips, or micro flakes, removed resulting in a tapered finish similar to native stone tools. The photos below show both the unworked and the chipped edges on the same glass base.

Close-up photos (below) taken with a high resolution microscope show flake scars on this glass artifact that suggest someone made these on purpose, by knapping the glass. Knapping or flint knapping refers to a stone tool technology. In its simplest terms, knapping is where stones are struck against each other in various ways to produce sharp flakes and shape raw stone materials into tools.

A further step in flint knapping is pressure flaking, where the edge is refined to create sharper and/or serrated edges for specific purposes. If the edge has been used, there will be even finer chipping or flake scars present. This artifact exhibits both a consistent flaking pattern and smaller micro chipping that indicates it was purposefully shaped and possibly used (photo C).

Glass properties are similar enough to chert and obsidian that it can be flint knapped into tools resembling prehistoric stone tools. A quick search on the internet will produce multiple modern day examples of knapped glass tools. This particular knapped glass base was found within a historic context. The foundation stones and historic artifacts recovered from the site suggested domestic usage from 1801 to 1950. So the presence of a historic glass artifact that may have been knapped poses many questions.

Who made it and why? Was it someone passing through who happened to have knowledge of flint knapping technology? Or was it someone who was a resident at the site? What was the cultural heritage of the individual or community at the site? As an archaeologist, it is my job to ask these questions and try to decipher the artifacts in hopes of discovering more about the history of the people that used to live in Kentucky.

In my research, I found there has been worked glass recovered throughout the United States and abroad, but there is not a clear consensus on the interpretation of these artifacts.  There is the issue of correctly identifying whether a historic glass fragment has been knapped, chipped by usage, or accidently chipped by circumstances (ie. disposal, plowing, agriculture). Knapped glass has also been found in Native American, African, and Euro-American context.

The most significant take away from the limited published research on this topic is the reminder that technology continues through the passing of information between humans over time via cultural practices and learned behaviors (also known as cultural transmission). The presence of knapped glass artifacts, like this piece, is evidence that some parts of flint knapping knowledge was likely passed down despite the consolidation and attempts to assimilate native inhabitants and their descendants. This means the first people of Kentucky used their flint knapping skills before, during, and after contact with Europeans. 

There is not enough diagnostic data present at the site to make a singular conclusion about the background of the individual who knapped this glass artifact.  Instead, this artifact serves as an example of the cultural complexities that existed but were not documented in Kentucky’s history. Artifacts like this one can start to shed light on questions like: Did mixed-heritage communities or households exist during and after the precontact period in Kentucky? How common was it? What are the specific mixed heritages present in Kentucky at the time? What specific social conditions could have allowed for something like native flint knapping technology to survive? How did it resurface within a historical context in central Kentucky?

Articles on knapped glass artifacts for further reading interests

Ahlman, T. M., Braly, B. R, & Schroedl, G. F. (2014). Stone Artifacts and Glass Tools from Enslaved African Contexts on St. Kitts’ Southeast Peninsula. Journal of African Diaspora Archaeology and Heritage, 3(1), 1–25.

Cooper, Z., & Bowdler, S. (1998). Flaked Glass Tools from the Andaman Islands and Australia. Asian Perspectives, 37(1), 74-83. Retrieved from

Conte, I., & Romero, F. (2008). Microwear Analysis of Retouched Glass Fragments from Fortlet Miñana, Azul, Argentina, 1860—1863. International Journal of Historical Archaeology, 12(3), 248-262. Retrieved from

Simmons, S. C. (2014). Exploring Colonization and Ethnogenesis through an Analysis of the Flaked Glass Tools of the Lower Columbia Chinookans and Fur Traders. Dissertations and Theses. Paper 1804.

Wachett, J. M. (2015). Knapped Glass: a practice of all cultures. The Post Hole, 42, 20-27.

Wilkie, L. (1996). Glass-Knapping at a Louisiana Plantation: African-American Tools? Historical Archaeology, 30(4), 37-49. Retrieved from


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