Why pottery matters so much
Fired clay is one of archaeology’s most useful materials. Pots were made in huge numbers, broke easily and were thrown away, yet the pieces survive for thousands of years almost unchanged. Because potters and their customers followed changing fashions and techniques, the shapes, clays and decoration of vessels vary across time and place. That variation lets archaeologists sort pottery into groups and then place those groups in order.
Pottery gives relative dates: it says that one deposit is probably earlier or later than another. It does not by itself say which year or century. For that, it has to be linked to written records, tree rings or radiocarbon samples.
Typology: sorting pottery into types
Typology is the process of classifying objects according to shared characteristics. For pottery, archaeologists commonly record several kinds of attribute:
- Fabric: the clay, and what was mixed into it, such as sand, crushed shell or straw.
- Form: bowl, jar, cup, storage vessel, and details like rim, handle and base.
- Surface treatment: smoothing, burnishing, slip, paint or glaze.
- Decoration: incised, impressed or painted motifs.
- Manufacture: handmade, coil-built, wheel-thrown or mould-made, and how it was fired.
Types are tools for study, so they are defined to answer questions, and different projects may classify the same material differently. Large excavations generally publish a type series, with drawings and descriptions, so that others can compare finds. In the Aegean, for example, Arthur Evans devised a scheme of Early, Middle and Late Minoan phases based on pottery styles from Knossos and other sites, and refinements of that scheme still underlie discussion of the Minoan civilization. The labels remain in use even though they were later adjusted and tied to absolute dates.
Some types act as markers. Mass-produced beveled-rim bowls are strongly associated with the Uruk period in Mesopotamia, so finding them far from southern Iraq suggests contact with that world. In Italy, the black burnished ware known as bucchero is a characteristic product of the Etruscans, and finding it elsewhere often indicates trade. Archaeologists sometimes call such diagnostic styles type fossils, borrowing a term from geology, though people are less predictable than species.
Seriation: ordering assemblages
Seriation arranges groups of finds into a sequence based on gradual change. The underlying idea is that a style typically appears, becomes popular and then declines, so its frequency in successive assemblages tends to rise and fall.
In the late 1890s, the Egyptologist Flinders Petrie faced hundreds of Predynastic graves with no written records and few clear layers. He wrote the contents of each grave on cards and rearranged them so that similar pottery types, and the ways they changed, formed a continuous series. He called the result sequence dating. Petrie’s approach was imperfect, and later scholars revised the details, but it showed that a sequence could be reconstructed from the objects alone.
Frequency seriation is a refinement used widely in the twentieth century. Assemblages are placed in the order that makes each type’s percentage form a smooth, single-peaked curve. When plotted as bars centred on a line, the shapes resemble the outlines of ships and are therefore informally called battleship curves. American archaeologists in the 1940s and 1950s developed these methods for the Southwest and the Southeast, and computers later made it easier to test the best ordering across many assemblages.
Where the sequence needs an anchor
A seriation gives an order but not the direction. Archaeologists need an independent clue to know which end is older. Stratigraphy is one source: the principles of tell stratigraphy mean that deeper layers are normally earlier. Imported pottery is another. When a distinctive vessel from one region turns up in a securely dated context in another, such as a tomb associated with a named ruler, it ties the sequence to the historical calendar. Radiocarbon dating and tree-ring dating of nearby samples can then calibrate the span of each phase.
Cross-dating of this kind is widely used, but it requires care. A vessel could be an heirloom, kept for generations, or reused long after it was made.
Limits and cautions
Several problems affect pottery-based chronologies:
- Styles do not change everywhere at once. A type may last longer in one region than another, so a sequence made in one valley cannot be assumed to hold in the next.
- Not all pottery is equally sensitive. Plain domestic wares may stay similar for centuries, whereas fine decorated wares change quickly but are rarer.
- Samples matter. Small assemblages, mixed deposits or disturbed layers can distort the order.
- Pots do not equal peoples. A style may show trade, imitation or shared taste, and it should not be equated with an ethnic group.
Modern work often adds scientific methods. Chemical analysis and thin-section microscopy can identify where clay came from, separating local products from imports. Residue analysis can detect what vessels once held. These tools complement typology instead of replacing it.
A foundation, not the final word
Pottery chronology remains a basic framework for much of archaeology, from the earliest farming villages to the wheel-thrown wares of later cities. Its strength is that it can be applied to ordinary sites with little else to go on. Its weakness is that it is only as good as the sample, the classification and the anchors that link it to real dates, which is why it is now usually combined with other dating evidence.