Dragana made several points relating to dating in the video. Dating is crucial for archaeology and we distinguish between two kinds of dating: relative and absolute. A relative chronology involves placing events in the relative sequence in which they took place (A happened before B, B before C etc.). Absolute dating provides not only a sequence of events but also a precise information when something took place (in which year or century, depending on the material one is working with).
Relative dating methods have been used in archaeology almost from its beginnings. They include stratigraphy (observing the sequence in which archaeological layers formed, about which you will learn more in week four) and typology of finds (systematic ordering of artefacts based on common attributes such as material, shape and decoration in order to determine the sequence in which they developed; this information is used to determine the sequence of contexts that these objects came from).
The only way to obtain an absolute calendar date in those days is to obtain it from one of the ancient sources. While this might have worked to an extent for Classical Antiquity or Egypt, the majority of past cultures had no comparable evidence to work from, and their chronologies were just floating sequences without any fixed points.
This changes after 1950s when due to several scientific breakthroughs methods were devised that allowed for precise absolute dating of archaeological material. These are mostly physical residue analysis of certain elements or properties for which we can reconstruct the original quantity or quality. For example the Radiocarbon dating that I mention dates organic materials based on how much Carbon 14 isotope is left in an organic material in its present state, while knowing how quickly that isotope breaks down and how much an organism would have originally contained. There are several other scientific methods working on a similar principle.
Please post any questions below, and also comments and links that can help others to learn about archaeology as a multidisciplinary endeavour.
The next video will go through the different scientific expertise that we use at Portus. There are then a video and two articles dealing with specific examples – the study of seeds, animal bones, and written materials. Please post your own thoughts on where archaeology sits in the humanities-sciences spectrum, and indeed whether you think it matters!