4.2.4 Producing the stratigraphic relationships of structural remains

Recognising the stratigraphic relationships between one wall segment and the next is an essential first step toward the necessary identification of large, individual construction events for producing a phased plan of a site. These events, termed Wall Construction Units (WCU) in our methodology, reflect the construction of several walls in a single event - the creation, for example, of a room, a suite of rooms, or even an entire (albeit simple) building - and therefore help to disentangle this event from preceding and subsequent events. A plan of wall construction units (Figure 12) dramatically reduces the complex appearance of the architecture compared to a plan of its wall segments (Figure 13). Moreover, key stratigraphic relationships (other than bonding) between individual wall segments help interpret the entire wall construction unit by indicating the relative chronology between wall construction units. For example, the fact that WS_003 of WCU_001 overlies WS_004 of WCU_002 means that WCU_001 is later than WCU_002 and was built only after WCU_002 went out of use (Figure 12).

Figure 12 Figure 13
Figure 12: Example of two Wall Construction Units. Inset: example of the Wall Segments that constitute the Wall Construction Units.
Figure 13: Detailed example (from inset of Figure 12) indicating the various Wall Segments that constitute the two Wall Construction Units.

However, many wall construction units do not have a direct physical relationship with each other and therefore have no observable stratigraphic relationship. In order to tie these masonry units together within a broader urban fabric it is necessary to turn to other forms of comparative evidence. Typological considerations, such as those of masonry construction techniques, choices of materials, and mortar types (Figure 14), are used in combination, along with other analogical considerations, such as those of the alignments of the constructions, and of their symmetry, and of the elevations of their foundations, destruction, and/or floor levels, to group wall construction units into larger units called Sub-Phases (SP) (Figure 15). These sub-phases constitute the first, basic, site-wide Harris Matrix (Figure 15, inset) of the relative chronology of these buildings and provide the best sense of the 'shape of space'.

Figure 14 Figure 15
Figure 14: The East Field at Isthmia, example of walls with Stratigraphic Relationships.
Figure 15: Example of a collection of Wall Construction Units that make up Sub-Phases.

In order to move beyond the spatial definition of the site and to combine the sub-phases into the largest of our abstractions, the phase, information must be incorporated from still other sources (Figure 16). Evidence from excavation and legacy data, including ancient texts where appropriate, is combined with the shape of the space provided by the sub-phases in the masonry analysis. The first goal is to move from the relative chronology into an absolute chronology using historically dated objects; this has the added benefit of further refining the relative sequence of construction by establishing the amount of time that occurred between the sub-phases. Additionally, finds data are used to determine the function of the space where possible. This has the potential to identify changes in use between the masonry sub-phases, as not all functional changes are represented by architectural changes.

Figure 16
Figure 16: The hierarchy of abstractions.

In summary, the phase is therefore the direct product of a process that begins with the observation of stratigraphic relationships among and between wall segments, wall faces, and non-architectural features. Then a suite of bonded wall segments are combined to form a wall construction unit, which is grouped with other wall construction units into sub-phases through both stratigraphic evidence and analogical inference. Finally, absolute dating and evidence for the function of spaces is incorporated to refine further the understanding of the site into phases.

Figure 17
Figure 17: Example of Phases.

While the phase plan (Figure 17) is a specific end product of this method, the process that creates it is a suitable and useful methodology for analysing complicated structural remains of a number of construction processes. In the first instance, the data-flow (the recording system and interconnections among the data) is structured to match the work-flow (on-site observation and analysis) to offer a predictive and flexible process. The problems resulting from more traditional masonry analysis methods, and the naming categories that these produce, are circumvented. Most importantly, a plan of the evidence is produced at each stage of the analysis (Figs 10, 12, 13, 15, and 17). These plans aid the interpretation of the site as a whole and of specific relative sequences at each stage in the process; such as those in a stretch of masonry (wall segment), in a bonded group of masonry constructions (wall construction unit), or in a bonded and typologically similar suite of architecture (sub-phase). Finally, these intermediate plans aid in the creation of the phase plans by giving shape to the space as well as providing base plans upon which to attach other legacy data from the written records of the original excavation.

The methodology described above attempts to adapt the way that masonry analyses are conducted so that they can produce data that fit more seamlessly with those produced by other archaeological methods, notably the recording procedures used for the original excavations. By abstracting the process of masonry analysis into a hierarchy of steps, this method guides both the on-site research and the data collected along appropriate analytical paths, ensuring that the evidence is recorded in appropriate formats that lead the analysis to the next step. This process is both iterative and additive. That is, each step produces a valuable tool for analysing the site in a linear manner. The method provides a standard platform both for the incorporation of existing data and for the inclusion of new evidence resulting from any expansion of an excavated area or site. The stability, flexibility, and concern for interoperability of this method make it useful in any archaeological context with complex architectural remains. By producing a phased plan of a site from evidence and interpretations that are transparent at each step in the process, this method creates more comparable data and takes an important step towards reducing the problems faced when attempting to combine new analyses with legacy data from old excavations.


© Internet Archaeology/Author(s) URL:
Last updated: Mon Jun 30 2008