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Introduction
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. 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. In point of fact, the situation is generally more complex, and, even more importantly, one must more sharply differentiate the two constitutive and very different aspects of statigraphy, emplacement and deposition.
These two aspects interact with each other as, respectively, the static and the dynamic moments of one and the same situation. Additionally, one should consider for each the possibility of measuring or dimensioning in space (emplacement) and time (deposition).
A full discussion of the concept of stratigraphy as followed here will be found in Chapter 42 of the Grammar. Here, a chart will help to summarize graphically the relative aspects of emplacement and volumetry on the one hand, and of deposition and sequencing on the other:
| static | dynamic | |
| descriptive | emplacement: internal characteristics and reciprocal contacts of things as they are in the ground | deposition: inferences about how things have come to be placed where they are |
| dimensioning | volumetry: metric measurements of things in space | sequencing: relative intervals in time |
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Relevance for documentation
The main reason why it is crucial that the distinction be closely maintained is that only emplacement can be properly observed and documented, while deposition can only be inferred (and hence cannot be documented). Since documentation is the main task of proper field work, it will be clear why the two must be kept rigorously distinct, even though it is impossible to deal with one without dealing at the same time with the other. In other words, it is not a matter of being blind to either one or the other, but rather to keep the levels of analysis separate, all the while one invokes both at one and the same time.
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Emplacement
Emplacement refers to the way things are in the ground. In particular, it aims to observe, document and describe (1) the nature and internal disposition of their inner components (e.g., alignment of inclusions) and (2) their reciprocal localization. With regard to the latter, it deals primarily with different types of direct contact.
The specific situations that are found in the current unit are discussed below.
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Sequencing
The correlation of all depositional moments that have been inferred from emplacement leads to the establishing of a broader depositional history that subsumes not only the sequence of narrowly confined areas (a locus, an area) but the entire site and is then in fact extrapolated to an entire region. It is in this context that one speaks of strata, phases and horizons as progressively more inclusive spans of time.
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Correlations between emplacement and deposition
The categories that define emplacement and deposition are closely interrelated, as is shown graphically in the synoptic chart below:
| emplacement | deposition |
| horizontal surfaces | floors |
| vertical buildup | deposits |
| amorphous amassment | fill, dumping, collapse |
| ordered organization | installations |
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