PREHISTORIC CERAMIC PRODUCTION: RAW MATERIALS AND FIRING METHODS 261 OF THE LA CROSSE LOCALITY ONEOTA Prehistoric Ceramic Production : Raw Materials and.·. Firing Methods of the La Crosse Locality Oneota

The Oneota who lived in large farming communities in the La Crosse locality from apPl"()~im(itely A.D. 1300 to 1625 are recognized by the characteristic ceramics tl1e¥ pfodllced. They manufactured shell-tempered ceramic vessels. that were much larger(indmore finely made than the grit-:-tempered pottery of the Woodland culturesthat inhabited Wisconsin prior to A.D. 1300. The use of shell· to decrease the porosity, improve the thermal efficiency and increase the durability of the resulting pottery presents a special problem. Under certain conditions when the calcium carbonate inthe shellis heated its chemical composition changes to a more unstable fonn known as calcium oxide. Calcium oxide is hygroscopic, meaning it absorbs moisture from the atmosphere. The absol"Ption of moisture by the calcium oxide causesfired pottery to crack and spall, weakening the strength of the pot and often causing it to crumble. Some attempts have been made to replicate the prehistoric pottery·found in the La Crosse area yet more experimentation is needed to under~··~~~··~·~rarn:ttt1trt~chniques and materials used to produce ceramics with properties similar to those of Oneota pottery. The replicas produced thus far were fired in the controlled environment of a kiln and do not exhibit the same properties as Oneota pottery and attempts to temper the clay with shell have met with spotty success. This research focuses on the problems associated with shell tempered ceramics through the production and testing of clay tiles made from local raw materials and firedllsil1g opel1-a.iffiril1g techniques and the comparison of these tiles with actual Oneota pottery sherds.