Seriation in archaeology is a relative dating technique where artefacts and assemblages (collections of artefacts) are separated and classified by style and frequency to create a relative chronology. Seriation can be used to date just about anything!
Sir William Flinders Petrie, who had assemblages from various Predynastic Egyptian cemeteries, first implemented this dating method. Without any stratigraphic evidence, he used the contents of these grave sites to create sequences based on design and popularity.
Objects evolve over time based both on style and function, and these changes can be organized and tracked to form relative dating chronologies over various archaeological sites to get a better understanding of the development and spread.
It is also worth noting that different types of artifact change in style (decoration and shape) at different rates, and therefore vary in the chronological distinctions that they indicate. As with even fashion today, decoration is likely to change more rapidly than shape does. So keep that in mind!
Like goes with like. When something is produced around the same time as something else, they usually look pretty similar. Whereas if you’re comparing objects of the same type that are a couple hundred years apart, they’ll probably look pretty different.
As styles change and develop, they gain more popularity and become more widely used. Then as a newer style or function comes into play, the older one starts to wane out. This pattern creates what we call a battleship curve, and this is the shape we look for when trying to configure our seriation sequence.
For more visuals and a walkthrough on how to complete a seriation sequence, watch the video above!
Let's do an experiment here:
Say we are from the year 2300 and we wanted to do a study on the use of cellphones in developing wanted to do a study on the spread of cellphone use from the 20th and 21st centuries. So what we do, is we find garbage pits or junkyards from that century, and take some samples.
Samples of different cell phones found in different landfills
We don’t have any sort of records for these pits and junkyards so all we have to go on is what we collect from the site. We then take all the phones we found from each site and make a graph of all the data to see how much of each phone we found at each site.
Next, we take these bars that we just created and separate them according to type.
From there, we sort them out to make what we call a battleship curve. Trends usually form in this way, starting small, getting bigger and then tapering out again. We look at all the sites in relation to one another and move them around until we get a pretty decent timeline. Don’t be afraid of some overlap.
And there you go! Seriation!
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Looking to Find Out More?
K. Kris Hirst, An Introduction to Seriation - Scientific Dating Before Radiocarbon
Colin Renfrew and Paul Bhan, Archaeology: Theories, Methods and Practice
O'Brien, Michael J. and R. Lee Lyman (1999). Seriation, Stratigraphy, and Index Fossils: The Backbone of Archaeological Dating. New York: Plenum Press.
McCafferty G. 2008. Seriation. In: Deborah MP, editor. Encyclopedia of Archaeology. New York: Academic Press. p 1976-1978.
Mary Richardson, Byron Gajewski, Archaeological Sampling Strategies, Journal of Statistics Education Volume 11, Number 1 (2003)
Rowe JH. 1961. Stratigraphy and seriation. American Antiquity 26(3):324-330
An Exercise in Seriation Dating - Society for American Archaeology