page_title: Stratigraphy (archaeology)
section_title: Stratigraphic dating
hierarchical_section_title: Stratigraphy (archaeology) / Stratigraphic dating
caption_attribution_description: graphic created for article harris matrix
context_page_description: Stratigraphy is a key concept to modern archaeological theory and practice. Modern excavation techniques are based on stratigraphic principles. The concept derives from the geological use of the idea that sedimentation takes place according to uniform principles.
  When archaeological finds are below the surface of the ground, the identification of the context of each find is vital in enabling the archaeologist to draw conclusions about the site and about the nature and date of its occupation. It is the archaeologist's role to attempt to discover what contexts exist and how they came to be created. Archaeological stratification or sequence is the dynamic superimposition of single units of stratigraphy, or contexts.
  Contexts are single events or actions that leave discrete, detectable traces in the archaeological sequence or stratigraphy. They can be deposits, structures, or "zero thickness surfaciques", better known as "cuts". Cuts represent actions that remove other solid contexts such as fills, deposits, and walls. An example would be a ditch "cut" through earlier deposits.
context_section_description: 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 figure A. Here we can see 12 contexts, each numbered with a unique context number and whose sequence is represented in the Harris matrix in figure 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.
caption: Figure A
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