DAACS Seriation Method
This page summarizes a frequency-seriation based chronology for the Building t site that was developed by DAACS (see Neiman, Galle, and Wheeler 2003 for technical details). DAACS seriated ceramic assemblages, with more than 5 sherds, from individual excavated contexts and from stratigraphic groups -- groups of contexts that field records indicate were part of a single stratigraphic layer or deposit. Stratigraphic groups have a SG-prefix, which precedes the group number (e.g. SG01 equals Stratigraphic Group 1). For example, at the Building t site, two portions of a single layer, described by the excavators a single fill deposit in a ditch, spanned several adjacent quadrats (945, 946, 952, 956, 970, and 969). The fill segments were excavated as 945D, 946B, 952A, 956B, 970A, and 969B. DAACS assigned these contexts to a single stratigraphic group (SG22). Not all contexts have stratigraphic group assignments.
DAACS chose to base the seriation chronology for the Building t site on ceramic assemblages aggregated at the level of contexts and stratigraphic groups, and not at the level of features. This is because most contexts and stratigraphic groups on the site were not parts of features. There was one exception. Artifacts from the 10 stratigraphic groups (SG08 through SG17) that comprised the deposits filling 4 subfloor pits (F01, F02, F03, F04) associated with the “Negro Quarter” (FG01) were combined into a single assemblage. These SGs were combined for the seriation because the common alignment of the pits attested to their broad contemporaneity. Where other stratigraphic groups and contexts were parts of features, the relevant feature numbers and descriptions are included in the seriation chronology table below.
DAACS computed the frequency of mean-ceramic-date (MCD) types in the 4 “Negro Quarter” subfloor pits, the other stratigraphic groups, and in individual contexts, when those contexts had no stratigraphic group assignment. The seriation chronology is derived from a correspondence analysis of these MCD-type frequencies. Seriated assemblages were assigned to phases. Phases are groups of assemblages that have similar correspondence-analysis scores and are therefore inferred to be broadly contemporary. Phases assigned by DAACS have a P-prefix that precedes the phase number (e.g. P01 equals Phase 1).
The stratigraphic relationships among stratigraphic groups and unassigned contexts are summarized in the Harris Matrix for the site. Phase assignments from the seriation are shown on the Harris Matrix in color, facilitating comparison of the seriation chronology and the stratigraphic chronology of the site.
Building t Site Phases
Based on the correspondence analysis, DAACS divided the Building t site occupation into 4 phases. The ceramic assemblage from the 4 subfloor pits beneath the early “Negro Quarter” emerged in the correspondence analysis as an outlier in relation to the other assemblages, signaling its distinctive composition, and justifying its placement in a separate phase (P01). The anomalously late mean ceramic date for this assemblage is a function of the 55 sherds of American Stoneware – most or all from the same vessel – found in three of the pits (F01:SG12, F02:SG14, F03:SG8). The Phase 2 assemblages represent the occupation of Building t, shown on the 1796 Mutual Assurance Plat, up to Jefferson’s death in 1826. The fill in the single subfloor pit beneath Building t dates to this phase (F05: SG25). Phases 3 and 4 contain successively greater amounts of material (e.g. whiteware) that postdate Jefferson’s death in 1826. The assemblage from the ditch (F06: SG22) on the northern edge of the site falls into Phase 3.
As is the case for all the Mulberry Row sites, the Building t site phases are massively time averaged. This is the result of both site formation processes and excavation and analytical errors which may have combined, in a single context or stratigraphic group, deposits from different time periods. Each phase represents deposition over many decades and there is considerable overlap between the periods represented by successive phases.
A Seriation Chronology for the Building t Site
The following table presents a seriation chronology for the Building l site. We use the indefinite article to signify that it is not the only chronology possible, nor the best. DAACS encourages users of Archive data to help explore improvements.