PRELIMINARY RAW MATERIAL SOURCING OF GROUND STONE TOOLS FOR A MISSISSIPPIAN STRUCTURE BASIN AT ANGEL MOUNDS STATE HISTORIC SITE

Raw material types are an important information source for archaeologists to consider when interpreting artifacts. It is widely understood that certain raw materials were selected due to certain qualities of the rock. Of the three major rock types, igneous and metamorphic are generally used to do more percussive work such as chopping, crushing, hammering, sometimes grinding, and as anvil stones. Sedimentary rocks such as sandstone and limestone are used more because of their abrasive qualities and were generally employed as grinding stone systems to process food and other materials, while handstone abraders were used to sharpen bone and wood tools. Though qualities such as these were preferred in certain tools, they are by no means mutually exclusive and occasionally sandstones were used as anvils--often these have harder cemented grains—but not always. Conversely, large grained quartzites or conglomerates were used as abraders.

The tools found in Unit A at Angel Mounds have an interesting spatial arrangement within the basin of the structure. The assemblage itself implies some kind of production occurred at the structure, specifically ceramic production. The 186 tools of a variety of raw material types are generally sourced to two places. The sedimentary (47.8% of assemblage) tools are fashioned from shale, limestone and sandstone. The limestone was quarried from a local source near the site and is from the Mississippian formation. The sandstone occurs within the Carbondale formation, which surrounds the entire area, and all of present day Evansville, Indiana rests upon. The second group of tools made from igneous (18.3% of assemblage) and metamorphic (33.9% of assemblage) rocks was most likely collected from the Ohio River and were geologically transported to the river system by glacial movement and subsequent processes.

The acquisition of raw materials has implications for the social network of the people, and is evidenced at least in part by the kinds of raw materials used to create ordinary and specialized tools such as the ones found in Unit A. The importance of a raw material source to provide a steady supply of tools for a site at which some form of production occurs is key to the site's vitality.