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Stratigraphy
The term “stratigraphy” is ubiquitous in archaeological discourse, but the concept is not generally as rigorously defined as one might wish. In a loose sense, it is often used to refer to a variety of concrete field situations where different elements overlay or intersect each other.
The concept originated in geology and has remained a core feature of this discipline, with a variety of methodological approaches having arisen in recent years. Catuneanu 2026 provides a comprehensive synthesis of eight distinctive types of geological stratigraphy, two of which have are particularly relevant for archaeology.
Allostratigraphy (Catuneanu, chapter 8) focuses on the interface among the constitutive elements – the term “allo” in the name referring to the discontinuities and bounding surfaces that are found among, and are thus “other than,” the building blocks of the system, i. e., the lithological elements which can be defined morphologically. This correponds to the types of contact among elements in archaeological stratigraphy.
Sequence stratigraphy (Catuneanu, chapter 9) focuses on the dynamics of events as they can be assumed on the basis of repetitive conformities especially in their surfaces as evidence of erosion and deposition. This is the most recent trend in geological stratigraphy, whereas it has been at the center of archaeological stratigraphy since the beginning, particularly in its effort at relating space and time as part of the same continuum.
Interestingly, no substantive mention is generally made, in discussions of geological stratigraphy, of archaeological stratigraphy. In effect, the latter differs in its essence from geological stratigraphy, even though the starting point is the same. The difference is instructive, and it needs to be brought out. A comparison is certianly useful for archaeology, as one think it should be for geology as well.
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Archaeological stratigraphy
Archaeological stratigraphic analysis differs in two respects from its geological counterpart, and it is a radical difference. What is at stake is both the context and the method.
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The same and the unique
The geological record is built around sameness. A given lithological element, definable in terms of distinct characteristics, is the same at different points, and this implies a regional or global tectonic event.
Archaeological stratigraphic analysis, on the other hand, is built around uniqueness. Each element, however minute, has a “dignity” of its own (Buccellati & Kelly-Buccellati 2026). This does not mean that there are no similar events that can have identical effects on elements, or that there are no similar phenomena to be identified in the record. Obvioulsy, excavation of a pit or the construction of a structure such as a wall are similar and hence “repetititve” – and so is a conical cup similar to hundreds of other conical cups found dispersed in the “strata” that have been deposited at a given site. But each event and each element must be viewed in and of itself, as specific and unique. Similarity is not sameness.
repetitive: horizons, periods
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The index and the whole
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Types of interaction
At its simplest, one thinks of layers that are horizontally placed one on top of the other, and a layer cake is the most commonly used metaphor for this situation. This is the principle of superposition, which is correct especially in a chronological sense (later events affect earlier ones after these have left elements in a certain “position”). Given the nature of the context, archaeological stratigraphy is highly distinctive. Later events often do not just cause elements to “lay” on top of earlier ones, in a layer-like fashion. They often intrude and disturb the earlier “layers” so that their original disposition is altered.
Another important factor is that the process, unlike what happens in geology, is non repetitive. Resulting from cultural activities, the depositional process is highly unpredictable, and must therefore be observed and recorded according to distinctive concepts and procedures – according to a distinctive, archaeological grammar.
At the basis of such a grammatical approach lies a sharp distinction between emplacement and deposition. One must observe and document each element as it is found in the ground in order to infer from it how it got there in the first place. To this we will turn our attention the following pages.
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References
Burgess & al 2021
ChatGPT 2026-420
Cateneanu 2006, 2026
Gavin
Harris
Mardon & al. 2021 esp. p. 111f
Wikipedia: Stratigraphy; Stratigraphy_(archaeology)
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