Scientific definition of carbon dating
The seriation method works because object styles change over time; they always have and always will.
A good example of a change in artifact type is the development of hand-held PDAs from those first enormous cell phones. As an example of how change through time works, consider the different music recording methods that were used in the 20th century.
Absolute dating techniques were not available to him (radiocarbon dating wasn't invented until the 1940s); and since they were separately excavated graves, stratigraphy was no use either.
Of all the music recording artifacts in our sample from Junkyard E, 10% are related to 45 rpm technology; 20% to 8-tracks; 60% are related to cassette tapes and 10% are CD-Rom parts.
It isn't possible to investigate all of a junkyard, so we'll pick a representative sample of the deposit.
We take our samples back to the laboratory, and count the kinds of artifacts in them, and discover that each of the junkyards have broken pieces of musical recording methods in them--old broken records, pieces of stereo equipment, 8-track cassette tapes.
His worrying about where a pot came from and what period it dated to and what that meant to the other objects buried with it were light-years away from the ideas represented in this photo dated to 1800, in which "Egyptian pots" was considered enough information for the thinking man.
Petrie was a scientific archaeologist, probably close to our first example.
The figure on this page is a Microsoft Excel (TM) table showing the results of our frequency count.