Ceramic analysis considers a number of attributes of both the manufacture and the decoration of pottery vessels. These include the shape of the vessel, the kinds of decoration, the way that the decoration was applied, where on the vessel the decoration was applied, the kind of temper that was used in manufacture, and the kind of clay.
Ceramic analysis might study the specific decoration on pottery, to determine when it was made, and how it compares to other types of pottery. Different regions and different time periods will have different decorations on their pottery, and often use different kinds of temper or make vessels in different shapes. These details help us to date the site, map trade and communication networks, and determine if several groups of people might be present.
The clay itself can also be examined. Each region has distinctive kinds of clay, often with slightly different minerals or other inclusions. Archaeologists can identify if a pot was made from the local clay, or if it was made of clay exotic to the area. If exotic, they may be able to pinpoint the source of the clay. This provides good information for discussing trade and communications networks.
Pottery first appears in Wisconsin about 2500 years ago. The designs change through time, just as styles of cars or clothing change, making pottery a very sensitive tool for dating sites. Specific changes occur in the temper, decoration and surface treatment of the vessel through time.
Woodland period (500 BC to 1200 AD) pottery is the oldest pottery found in Wisconsin. The oldest pottery has sand or crushed rock (grit) mixed with the clay. The body of the vessel was usually formed by coiling strips of clay. The pot was shaped with a paddle wrapped in cords, leaving a characteristic cord-roughened surface. Sometimes this surface was smoothed over, or covered with a pattern created by pressing a mussel shell into the clay at alternating angles (rocker stamping). Decoration was done using fingernails, sharp tools, twisted cords, net-like fabrics, a cord-wrapped stick, rocker stamps, or dentate stamps (sticks with a series of carved notches that were pressed in the clay).
Oneota pottery (1200 AD to 1625 AD) was tempered with crushed, burned mussel shells. The vessels are much larger, and were probably formed by modeling lumps of clay. The body of the vessel has a smooth surface. Decoration was done using fingers or sticks to make trails and dots (punctates) in the wet clay.
The oldest pots (Woodland) vary from flat bottoms with straight walls (Marion) to globular with a conical bottom (Madison). Oneota pottery is also globular with a conical bottom and flared rim, and often has two handles.
The oldest Woodland pots held about half a gallon, while more recent Woodland vessels held two to three gallons. Full-size Oneota vessels held 10 to 15 gallons.