3. Deposition

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Concepts

Deposition (or depositional process) is the way in which things got where they are in the ground, and depositional history is the construct that describes that process. It is not observable in and of itself, but is rather based on inference from observations of emplacement. These inferences bear directly on chronology and function.

The classification of features according to depositional categories depends essentially on the manner in which the process can be inferred to have happened, i.e., on the manner of origin of the emplacement. The major types are shown graphically in the following chart.

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Correlations between emplacement and deposition – and typology

To be sure, the categories that define emplacement and deposition are closely interrelated, just as they are in turn with typology. Ultimately, it is the typological definition that we use currently – a definition that is discussed under typology. But it is important to keep the various levels of analysis distinct, and to have the conceptual tools for doing so. This is the goal we pursue within the framework of the Urkesh Global Record.

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Depositional and structural history

Depositional history is not limited to deposits in the technical sense of the term, i.e., gradual and unintended build-up. It refers as well to the way in which buildings developed over time as they underwent structural changes. In this case, one can discover an inner stratigraphic history which is declared by the way in which the structural components are juxtaposed in space.

The simplest observation in this regard pertains to the sequence in which the components must have been set in place: obviously, the laying of foundations precedes the erection of a wall.

Other cases present a more nuanced situation. If the lower part of a brick wall is made of different bricks than the upper part, is it because the supply of a certain type was exhausted, or because at some point the roof was removed and the walls were raised to support a new roof?

In either case, we can assume temporal succession, but obviously the moments of this succession appear to have different weight depending on other concomitant considerations. We can link these “moments” to strata by correlating the structural observations to other depositional factors.
This approach, which has always been central to archaeology, has been developed more fully in what has become an independent discipline, which may be called the developmental analysis of architecture.

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“Harris matrix” and depositional synopsis

The so-called “Harris matrix” is widely used to chart stratigraphic sequences. Undoubtedly a most useful tool, I feel that its nature is often not properly understood, and that its effective range is limited. As an important complementary tool I propose a depositional index and synopsis, as alternative way to chart the depositional process.