Friday, March 13, 2015

Groovin' with stone axes

This week in our alphabetical trip through Pennsylvania archaeology, we have reached the letter “X”; and, to keep it simple, “X” stands for axes, specifically stone axes.

Axes are one of several hafted stone tool types that are differentiated by the angle at which the head is seated. An axe blade or head, is hafted parallel to the handle rather than perpendicular to the handle as in hoes or adzes. There are two basic axe forms; chipped axes and pecked and polished axes. Chipped axes have two opposing notches and the notches were used in the hafting process. They are relatively simple to make and were used during many time periods in prehistory. Ground and polished axes are grooved for securing the head to the handle. A full grooved axe has a groove that encircles the entire piece. On the ¾ grooved axes, the groove does not extend to the bottom side.

chipped axe

sketch of full grooved axe

sketch of 3/4 grooved axe

Ground and polished axes frequently start out as river cobbles that were chosen for their general size and shape. Metamorphosed siltstone or sandstone, basalt or diabase was frequently used and sometimes quartzite. Depending on the degree of stone that needed to be removed to reach the desired shape, axes are first chipped to remove excess material or if only a small amount of material needs to be removed, they are pecked into shape. The pecking process involves using a stone hammer and repeatedly but carefully striking the axe blank, removing small pieces of the surface. The groove formed early in the manufacturing process. Once the entire surface was pecked to the desired shape, the axe blank was rubbed on a piece of sandstone to smooth the surface. Although not found in Pennsylvania, special axe grinding slabs have been found in the western United States. In order to attain a very high polish, the final rubbing takes place on a charred piece of wood.  

groove started on an axe blank

Full grooved and ¾ grooved axes were hafted slightly differently as can be observed in the figure below. The functional differences, however, are not clear. In addition, sometimes the groove is bordered by a ridge on one or both sides and sometime there is a double groove. It is assumed that this was part of the hafting method but again, the functional differences are not clear. Depending on the hardness of the stone, the manufacturing process for a full grooved and completely polished axe required 30 to 60 hours of work.

sketch of hafted axes

finished full groove axe

finished 3/4 grooved axe

double grooved axe

Axes were sharpened by simply grinding down the bit end as it became worn. Most of the axes in The State Museum collection are broken or worn down, nearing the end of their use life. However, some are very large (see below) and some of the unfinished pieces are extremely heavy weighing 4445 gr or 10 pounds and measuring 39 cm or 15 inches in length.

large finished full grooved axe

longest axe

 heaviest axe

Native Americans have been using axes to cut wood ever since they arrived in North America. However, during the Paleoindian period (11,700 - 20,000 BP.) they are neither notched or polished and difficult to identify unless systematic microwear studies are conducted. It is not until the Middle Archaic period (6850 – 10,200 BP.) that ground and polished axes are produced. Full grooved axes are the earliest and ¾ grooved axes do not appear until the (Late Archaic 4850 – 6850 BP.) and become common during the Transitional period (2800 – 4850 BP.).

            The State Museum is initiating an inventory and preliminary analysis of its unprovenienced collection of grooved and chipped stone axes. This group of artifacts was received as part of various donated collections such as those from Gerald Fenstermaker and Samuel Farver and are not located by specific site. They are primarily from eastern Pennsylvania and mainly the Susquehanna drainage basin. Up until a month ago, they were stored in boxes and underutilized. For exhibit or research purposes, we didn’t know what we had unless we inventoried and catalogued all 54 boxes. Our goal is to make a list of all that we have, catalogue them by type and take some basic measurements to determine variations in size, breakage patterns, how they were made and the lithic materials that were used. Our intern this semester, Tamara Eichelberger from Elizabethtown College, has volunteered to process the collection. Although they had been washed sometime in the past, over 40 years of dust had accumulated so they needed to be wiped clean. Since each will be measured and entered into a data base, each needs an individual catalogue and specimen number. With the help of volunteers, Tamara is completing the labeling process and will begin taking measurements next week. There are over 500 specimens in the collection so she should be able to develop a good characterization of axes from eastern Pennsylvania. The results of her analysis will be the subject of a blog in early May.

Tam and her axes

Additional reading

Adams Jenny L.

2014    Ground Stone Analysis: A Technological Approach. The University of Utah Press, Salt Lake City. 

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

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