Archaeological Stratigraphy — Stratigraphic Excavation and Sequence Analysis
Archaeological Stratigraphic Analysis · Also known as: stratigraphic excavation, Harris matrix method, stratigraphic sequence analysis, layer-by-layer excavation
Archaeological stratigraphy is the systematic excavation and recording of soil layers, deposits, and features at an archaeological site in order to establish the relative chronological sequence of human activity. Grounded in the geological law of superposition — that lower layers are older than those above — it uses the Harris Matrix as a formal tool to map depositional relationships and reconstruct site history layer by layer.
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When to use it
Use archaeological stratigraphy whenever you are excavating a site with multiple occupation phases, cut features, or accumulated deposits and need to establish a reliable chronological sequence of activity. It is the standard method for all complex multi-period sites, urban archaeology, and any context where finds must be placed in depositional order. It is essential when the research question concerns the timing, succession, or duration of past human activities. It is not appropriate as a standalone method for surface scatters with no depth, for sites that have been completely disturbed by modern activity (rendering layers unreadable), or for answering questions that require population-level data rather than site-specific sequences.
Strengths & limitations
- Provides the only reliable relative chronological sequence for the events and deposits recorded at a site.
- The Harris Matrix formalises stratigraphic relationships in a transparent, reproducible diagram that can be shared and critiqued.
- Integrates naturally with absolute dating techniques, finds typology, and environmental sampling to build a comprehensive site history.
- Applicable to sites of any period — from prehistoric to post-medieval — and any geographic region.
- The context-by-context recording system creates an auditable archive that supports subsequent reanalysis.
- Excavation is inherently destructive: once a layer is removed it cannot be re-excavated in its original state.
- Stratigraphy yields relative, not absolute, dates on its own; independent scientific dating is required to anchor the sequence in time.
- Highly complex sites with thousands of contexts demand substantial time, labour, and specialist expertise to excavate and record correctly.
- Post-depositional processes (bioturbation, flooding, ploughing) can mix or destroy layers, making the sequence ambiguous or misleading.
Frequently asked
What is the Harris Matrix and is it always necessary?
The Harris Matrix is a directed acyclic graph that records the stratigraphic relationships between all contexts at a site — which are above, below, or contemporary with others. It is not strictly obligatory on a simple single-phase site, but on any multi-period or complex site it is the professional standard. Without it the relative sequence exists only in the excavator's memory rather than in a documented, peer-reviewable record.
How does stratigraphic sequence differ from absolute dating?
Stratigraphic sequence is a relative order — Context A was deposited before Context B — without specifying calendar years. Absolute dating (radiocarbon, dendrochronology, coin dates) attaches calendar-year estimates to specific points in the sequence. Both are normally used together: stratigraphy provides the framework, absolute dates anchor it in time.
Can stratigraphy be applied to sites with no visible layers?
Shallow or heavily ploughed sites may appear layer-free at the surface, but individual cut features (pits, post-holes, ditches) still retain internal stratigraphic relationships. Micro-stratigraphic techniques using sediment micromorphology can also reveal depositional sequences invisible to the naked eye. Truly unstratified surface scatters are the exception where standard stratigraphic methods cannot be applied.
Who owns the stratigraphic record once excavation is complete?
In most jurisdictions the site archive — all context sheets, drawings, photographs, and finds — must be deposited in a recognised repository (museum, archive, or national records office) and made accessible for future researchers. The destructive nature of excavation means that the archive is the primary evidence; its loss or inaccessibility is an irreversible research loss.
How does stratigraphy relate to typological analysis?
Typology and stratigraphy are complementary: stratigraphy places finds in depositional order, and typology uses the forms and styles of objects (pottery, coins, tools) to assign dates or cultural affiliations. Finds from a well-stratified context can refine typological chronologies; conversely, a datable find type anchors a stratigraphic layer in time. The two methods validate and reinforce each other.
Sources
- Harris, E. C. (1979). Principles of Archaeological Stratigraphy. Academic Press. ISBN: 978-0123264220
- Renfrew, C., & Bahn, P. (2016). Archaeology: Theories, Methods, and Practice (7th ed.). Thames & Hudson. ISBN: 978-0500292006
How to cite this page
ScholarGate. (2026, June 3). Archaeological Stratigraphic Analysis. ScholarGate. https://scholargate.app/en/field-methods/archaeological-stratigraphy
Which method?
Set this method beside its closest kin and read them side by side — the library lays the books on the table; the choice is yours.
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