By Lotte Govaerts
Why is the study of ceramics so prevalent in archaeology?
There are a few reasons: First, clay has always been an abundantly available resource. People all over the world have had easy access to clay throughout history and prehistory. Most human cultures made use of it. They shaped and fired clay to make ceramic vessels of various forms, as well as figurines, architectural elements and other objects (in this post I will only talk about pots, though). The pervasive use of ceramics is fortunate for archaeologists, because although fired clay is breakable, it’s also very durable. Pottery can last a very, very long time in archaeological contexts. Unlike metal, which corrodes in almost all environments, and unlike organic materials like bone or wood, which rot away more or less rapidly depending on circumstances, fired clay can last almost indefinitely. Pottery isn’t indestructible. Clay fired at relatively low temperatures is somewhat prone to erosion and cracks. Even so, it isn’t uncommon for us to find pieces of pottery (sherds) that are hundreds or thousands of years old, yet look like they broke last month.
Some of the "Middle Missouri" potsherds from archaeological site 39ST56 in South Dakota, which we have been (re-) cataloging recently. Photo by Lotte Govaerts.
What can we learn from the pot sherds we find?
Sometimes we find whole pots. This could happen in undisturbed burial contexts, or more exceptionally, if a house or even a whole town was buried quickly, like at Pompeii, which was buried under volcanic ash in AD 79. Far more often, however, what we find are pieces of broken pots. Sometimes all the pieces of a pot are found right where it fell, and we can easily put them back together. Some small pieces are usually lost to the long-term effects of rodent burrows or tree roots, but we can still make a reconstruction that looks almost exactly like the vessel would have looked before it broke. However, it is more common for sherds to get scattered after a vessel breaks. They might get walked on or kicked around. They might get swept up into a trash pit. Some of the larger pieces might be put to use as digging tools, and later discarded elsewhere. Someone interested in reassembling broken pots might find pieces of a single vessel spread out over various contexts. Restoring a pot from scattered sherds can be very satisfying, but it’s obviously not always possible, nor is it always necessary. We can learn a lot about pots from just fragments, too!
A small collection of Aztec and Matlatzinca tripod bowls in storage here at the Smithsonian's National Museum of Natural History' s Department of Anthropology. These bowls were excavated in the late 19th century in Mexico's Toluca Valley. Photo by Lotte Govaerts.
For example, from a single sherd we can make certain observations about things like color, form, and decorations. We also consider the type of clay, firing methods, and type of tempering agent used. Temper is a material added to the clay by the potter to reduce breakage during firing. A wide variety of materials was used for this purpose, like crushed rocks, sand, shell, grass, and even ground up old pots. By measuring the curve of a rim sherd, we can determine the size of a vessel’s opening. Being familiar with the pottery of a particular time/place/culture can allow an archaeologist to estimate the distribution of vessel forms and ceramics types at a site by just assessing a collection of small sherds.
Dan Rogers teaches Julia and Maddy how to measure a vessel's (approximate) opening diameter using rim sherds, here at the Rogers Archaeology Lab. Photo by Meghan Mulkerin.
Careful study of vessel forms and decorations allows archaeologists to construct a “relative chronology” for a certain area and time period. Once we figure out how certain styles of pottery evolved over time in a given area, we can then use sherd styles to date other contexts.
Some attributes of sherds can’t be seen with the naked eye. But we have all kinds of advanced technology to help with that! We can determine the source of the clay via chemical analysis. If paint is used for decoration, that can be similarly analyzed. We can visualize painted decorations that have faded with time, based on the identification of minute pigment particles left behind on the vessel. Through residue analysis, we can sometimes determine what a vessel once contained. Some people even study the fingerprints left behind on ancient pottery when the pots were made!
Meghan holds up a partially reconstructed vessel from another Middle Missouri site (39ST224) in South Dakota. Photo by Lotte Govaerts.
So, what does all this tell us?
Although observations about a ceramic artifact might be interesting on their own, archaeology is not about single objects. Archaeologists always try to learn something about a specific society, or about humankind in general. We learn by integrating observations about ceramics and other artifacts with each other and with facts we already know. Ceramic artifacts can tell us about technology and how it changed over time, about social organization and issues relating to status or class, about trade networks, about what types of goods were traded, about style and fashion and how they change over time, about how ideas are transferred, about food and drink, and about so many other things!