Stratigraphic Relationships
Archaeologists investigating a site may wish to date the activity rather than artifacts on site by dating the individual contexts which represents events. Some degree of dating objects by their position in the sequence can be made with known datable elements of the archaeological record or other assumed datable contexts deduced by a regressive form of relative dating which in turn can fix events represented by contexts to some range in time. For example the date of formation of a context which is totally sealed between two datable layers will fall between the dates of the two layers sealing it. However the date of contexts often fall in a range of possibilities so using them to date others is not a straightforward process.
Take the hypothetical section fig A. Here we can see 12 contexts, each numbered with a unique context number and whose sequence is represented in the Harris matrix in fig B.
- A horizontal layer
- Masonry wall remnant
- Backfill of the wall construction trench (sometimes called construction cut)
- A horizontal layer, probably the same as 1
- Construction cut for wall 2
- A clay floor abutting wall 2
- Fill of shallow cut 8
- Shallow pit cut
- A horizontal layer
- A horizontal layer, probably the same as 9
- Natural sterile ground formed before human occupation of the site
- Trample in the base of cut 5 formed by workmen's boots constructing the structure wall 2 and floor 6 is associated with.
If we know the date of context 1 and context 9 we can deduce that context 7, the backfilling of pit 8, occurred sometime after the date for 9 but before the date for 1, and if we recover an assemblage of artifacts from context 7 that occur nowhere else in the sequence, we have isolated them with a reasonable degree of certainty to a discrete range of time. In this instance we can now use the date we have for finds in context 7 to date other sites and sequences. In practice a huge amount of cross referencing with other recorded sequences is required to produce dating series from stratigraphic relationships such as the work in seriation.
Read more about this topic: Dating Methodologies In Archaeology