Dating techniques in archaeology
Plotting several curves can allow the archaeologist to develop a relative chronology for an entire site or group of sites.
For detailed information about how seriation works, see Seriation: A Step by Step Description.
Cross-dating of sites, comparing geologic strata at one site with another location and extrapolating the relative ages in that manner, is still an important dating strategy used today, primarily when sites are far too old for absolute dates to have much meaning.
The scholar most associated with the rules of stratigraphy (or law of superposition) is probably the geologist Charles Lyell.
First used, and likely invented by archaeologist Sir William Flinders-Petrie in 1899, seriation (or sequence dating) is based on the idea that artifacts change over time.
For more information on stratigraphy and how it is used in archaeology, see the Stratigraphy glossary entry.Seriation, on the other hand, was a stroke of genius.