Microwear analysis-determining the function of chipped stone tools

One of my technical specialties is high-powered microwear analysis, a method by which the function of chipped stone tools can be determined. Pioneered by Semenov (1964) and refined by Keeley (1980), the high-powered magnification approach has repeatedly demonstrated that variability in polish formation on utilized surfaces is related to tool use on different materials (e.g. soft tissue, hide, bone, wood, etc.). Striations, or the grooves and scratches of varying orientation and dimensions which often result from abrasive forces imparted during tool use are important indicators of intentional and unintentional motion, such as friction between a stone tool and its haft and/or the contact material being worked.  Taken together, micropolish and striations provide information on contact material, tool motion, and hafting.  In this manner, the identification of distinct surface and edge alteration of tools can be related to prehistoric patterns of activity and raw material use and utilized in the reconstruction of the organization of cultural behaviors.

Today I continue to work on material from three sites. Two sites were recently excavated by a Cultural Resource Management firm as contract excavations. These sites, which date from the Late Archaic and Woodland periods, were investigated to fufill compliance laws prior to disturbance. As part of the data recovery plans, the principle investigators have included a budget for analysis, a part of which is microwear analysis to determine the function of chipped stone tools recovered on site. A range of formal and informal tools were recovered, and so far, results indicate a wide variety of tasks  including butchery, hide,  and bone and wood working occurred on site.

The third site I am working on is the famous Lindenmeier Folsom site in Colorado. These materials were excavated and/or collected in 1934-40 during work at the site by Frank Roberts. Microwear analysis of a sample of endscrapers recovered from the site reveal that many of them were employed in the later stages of hide working. Edge wear in the form of eroded resharpening scars and heavily rounded edges along with a well formed dull-pitted polish characteristic of dry hide was present (see photomicrograph).  During late stage hide working, the edges of the tools are allowed to dull, so that accidental tearing of the hide during stretching and softening is lessened. Some endscrapers were discarded with sharp, fresh edges indicating use during earlier stages of hide working where cleaning and thinning is the object. These discard patterns illuminate the activities that took place on site, and when coupled with an assemblage of worn out, broken and discarded projectile points suggest active hunting and transport of fresh hides for processing at the site was common.  Here is a prime example of the value of why collections should be curated, as when they continue to be available for analysis, we can continue to learn from them.

Heavily worn and rounded distal edge of unifacial endscraper used on dry hide.