Stratigraphy and the Harris Matrix

Archaeological stratigraphy is the study of the layered sequence of deposits and the relationships between them; the Harris matrix is the standard diagram for expressing that sequence as a relative chronology.

Definition

The analysis of the depositional and erosional sequence at an archaeological site, formalized through the Harris matrix, a diagram that orders individual contexts by their stratigraphic relationships into a relative chronology.

Scope

This topic covers the laws of archaeological stratigraphy, the identification and definition of contexts (layers, cuts, and fills), the principle of single-context recording, and the construction of the Harris matrix to represent stratigraphic relationships as a directed sequence independent of absolute dates.

Core questions

• What are the laws governing how archaeological deposits accumulate and relate?
• How is an individual context defined, recorded, and assigned a number?
• How does the Harris matrix convert physical layering into a relative sequence?
• How are absolute dates and phasing mapped onto a stratigraphic matrix?

Key theories

Laws of archaeological stratigraphy

Harris's adaptation of geological superposition into laws of superposition, original horizontality, original continuity, and stratigraphic succession that govern how archaeological deposits are ordered in time.

Single-context recording and the matrix

The method of recording each deposit or cut as a discrete unit and expressing only its immediate stratigraphic relationships, which combine into the Harris matrix as the site's relative chronology.

History

Archaeological stratigraphy was first borrowed from geology in the 19th century but remained tied to visible sections until Edward Harris, working in Winchester in the early 1970s, devised the matrix that bears his name. His 1979 Principles of Archaeological Stratigraphy, revised in 1989, established single-context recording and the matrix as standard practice in urban and open-area excavation.

Debates

Interpreting matrices and grouping contexts into phases

Practitioners debate how individual contexts should be grouped into stratigraphic phases and how much interpretation belongs in the matrix itself versus in separate phasing, especially on complex urban sites.

Key figures

• Edward C. Harris
• Steve Roskams
• Philip Barker

Seminal works

• harris1989
• harrisetal1993

Frequently asked questions

What is a context in archaeology?

A context is a single, distinct event in the formation of a site, such as a layer, a wall, or a cut like a pit, which is recorded as one unit and given a unique number.

What does a Harris matrix show?

It shows the relative order in which contexts were formed, expressed as a flow diagram of which contexts are earlier or later than others, without assuming any absolute calendar dates.