Minnesota Prehistory

Pottery Making

Pottery, one of the first synthetics created by man, is created by a dehydration process. The process in which clay is heated and the water found naturally in it is removed, causes an irreversible transformation. In other words the clay is not simply dehydrated but it become a different product all together. This new product is ceramics, which are unchanged by the presence of water because of absence of water of plasticity. Water of plasticity is the substance that allows for clay to be wetted and dried over and over again without permanent change. However, when clay is heated in excess of 500 degrees centigrade another reaction occurs causing permanent and irreversible change. This degree of heating causes the water of hydration to be "driven off."

Most often, clays are tempered in the process of pottery making. Tempering is a process in which materials are added to the clay to help the product resist cracking in the final stages of ceramic production. Many different materials may be used in the tempering process including shell (common among many prehistoric Minnesota peoples), sand and pieces of old pottery. The choice of material in the tempering process is often helpful to archaeologists as it is usually culturally based and easily identifiable.

Decoration and pottery shape are very specific to culture. It is easy to determine one time period or culture from another by specific patterns or handles found on the respective ceramics. Firing is the final step in the creation of ceramics. Most kilns used for firing pottery consist of two separate chambers, one for the fire and one for the ceramics. Other forms of firing include such primitive but still effective practices as having a ring of fire and placing the clay around the fire, or starting a fire in the middle of a ring of clay wares.

Pottery artifacts are prime cultural identifiers in the study of Minnesota Prehistory. Specific types of pottery are identifiers in understanding the age, type, and location, as well as status of occupants at an archaeological sites. Click below for examples of Ceramic and pottery artifacts found throughout Minnesota.