Harris matrix
One of the results of Harris's work, however, was the realisation that sites had to be excavated stratigraphically, in the reverse order to that in which they were created, without the use of arbitrary measures of stratification such as spits or planums.
In his Principles of archaeological stratigraphy Harris first proposed the need for each unit of stratification to have its own graphic representation, usually in the form of a measured plan.
[1] A fifth law has been added following papers presented at the "Interpreting Stratigraphy: a Review of the Art" conferences in the UK from 1992 to 2003.In a series of layers and interfacial features, as originally created, the upper units of stratification are younger and the lower are older, for each must have been deposited on, or created by the removal of, a pre-existing mass of archaeological stratification.
Therefore, if any edge of the deposit is exposed in a vertical plane view, a part of its original extent must have been removed by excavation or erosion: its continuity must be sought, or its absence explained.
The Harris matrix is a tool that aids the accurate and consistent excavation of a site and articulates complex sequences in a clear and understandable way.
Harris matrices play an invaluable role in the articulation of sequence and provide the building blocks from which higher order units of stratigraphically related events can be constructed.
As long as undercutting is not endemic, in practice onsite errors in judgment should become evident especially if temporary sections are kept for stratigraphic control in areas of a site that are hard to discern.
The use of archaeological sections when dealing with stratigraphic complexity is limited and their use should be context-sensitive rather than as a running arbiter of sequence.
This diagram, which is based on the Harris matrix, is designed to represent the time lapse in use of recognizable archaeological entities such as floors and pits.
Like Edward Harris, he used contexts numbered and defined on site as the basic elements of the sequence, but he added higher order groupings ("feature" and "structure") to increase the interpretive power.
