Interpreting broken pottery: Exploring rim diameters

Submitted by Sammy Smith (sammy@thesga.org)

Archaeologists may find themselves faced by piles and bags of broken pottery that they need to interpret.

Interpretation begins with trying to see which pieces fit together and what size and shape the vessels they came from were when they were whole.

The reconstruction information is combined with where the broken pieces were found—their all-important context, or provenience—to figure out how the whole vessels might have been used.

Although this may sound straightforward, it can be very complicated.

One way archaeologists determine the size of pottery vessels is to take rim or lip sherds—those from the open edge of the vessel. Indeed, one of the ArchaeoBus activities helps visitors to learn about this technique.

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The curved rims of the broken pieces are compared to the pre-measured curves on this chart to determine the diameter of the opening they framed.

How would you interpret the following data? What if you had 300 rim sherds, and about 1/3 measured about 11 inches in diameter, the rest measured about 6 inches in diameter?

This is similar to the pattern that the following vessels might yield.

DIA_wine_water_jugs_top.jpg

Note however, that although the openings of the two vessels on the right are similar, the vessel shapes are quite different. These three vessels are on display at the Detroit Institute of Arts. The middle one is the most vertical and narrow of the three, while the one on the right is full-bellied.

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The three vessels are ancient Greek vessels with specific usages. The one in the middle was used for carrying wine, and is called an amphora. This particular amphora dates to 540–520 BC. Some amphorae had a rounded bottom, and needed a coiled shape to rest in to remain upright. Wine and olive oil were shipped around the Mediterranean in amphorae.

The vessel on the right was for carrying water, and called a hydria. This hydria dates to 475–450 BC.

The narrowed necks on these two vessel types made the liquid in them less likely to spill when they were moved.

The vessel on the left has a wide-mouth, and is called a krater. It dates to the 300s BC.

The ancient Greeks considered it more civilized to mix wine and water rather than drinking the wine straight. When feasting or entertaining, wealthy Greeks would have all three vessels at hand. The wine and water would be mixed in the krater, then served to diners.

Because of historical information, we know how Greek vessels with these distinct shapes were used. However, these uses are sometimes confirmed by images on the vessels. The hydria, for example, shows a woman getting water from a well.

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Now that you’ve learned about these three types of large Greek vessels, the amphora for wine, the hydria for water, and the krater for mixing and serving the two, what kind of vessel do you think the one at the right is?

What if the group of rim sherds you measure instead were about 5 percent very large, maybe 15 inches in diameter, and the rest were 4 to 5 inches in diameter?

A similar pattern to this has been interpreted as follows. The large vessels were serving vessels and the many small vessels were personal eating bowls. This kind of pattern has been observed when large groups of workers has been marshalled for communal labor activities.

What have you learned from this discussion of ceramic rim diameters, based on collections of broken pottery from known contexts?