Building r Chronology
DAACS has developed an uniform set of methods to infer intra-site chronologies for the sites included in the Archive. Using them, we have assigned most excavated contexts at each site to a set of site-specific phases. The use of common methods is designed to increase comparability among phases at different sites. The methods and the phase assignments they produced are summarized below. For some sites, the original excavators developed intra-site chronologies and where these exist, they are included on the Background page for the site. DAACS encourages users of Archive data to help explore improvements.
DAACS Seriation Method
This page summarizes a frequency-seriation based chronology for the Building r site that was developed by DAACS (see Neiman, Galle, and Wheeler 2003 for technical details). DAACS seriated ceramic assemblages, with more than five 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. DAACS assigned such contexts to the same stratigraphic group. Stratigraphic groups have a SG-prefix, which precedes the group number (e.g. SG01 equals Stratigraphic Group 1). For example, at the Building r site, two portions of a single layer, described by the excavators as ‘heavy charcoal and ash”, spanned two adjacent quadrats (745 and 787). The layer segments were excavated as 745A and 787B. DAACS assigned these contexts to a single stratigraphic group (SG08). Not all contexts have stratigraphic group assignments.
DAACS chose to base the seriation chronology for the Building r 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. In the few cases where 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 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 r Site Phases
Based on the correspondence analysis, DAACS divided the Building r site occupation into four phases. Mean ceramic dates for the four phases are given in the table below. The table also included two estimates of the ceramic TPQ for each phase. The first TPQ estimate is the usual one – the maximum beginning manufacturing date among all the MCD types in the assemblage. The second estimate -- TPQp90 -- is the 90th percentile of the beginning manufacturing dates among all the shreds in the assemblage, based on their MCD types. This second TPQ estimate is more robust against excavation errors and taphonomic processes that might have introduced a few anomalously late sherds into an assemblage.
The phases for the Building r site are among the most massively time averaged on Mulberry Row. This is due to the grading that took place on the site in the 1930’s for construction of a parking lot. Phase 1 is nearly entirely comprised of material from the Jefferson-era occupation of the site, by the inhabitants of Building r, as shown on the 1796 Mutual Assurance Plat. The Phase 2 assemblage has a nearly identical MCD, but its 1840 TPQ indicates it also contains small amounts of post-Jefferson material. A small assemblage from the builder’s trench (F03) for a brick pier of the Brick-Pier Structure (FG01) dates to this phase. So does a small assemblage from a posthole (F18) belonging to a fence line (FG04) just south of the site of Building r. A large feature (F34, SG09), probably a tree disturbance, at the north edge of the site also dates to this phase. Phase 3 contains significantly more post-Jefferson material, as indicated by its 1828 TPQp90 . This phase is largely comprised of two assemblages from stratigraphic groups (SG02, SG05) that the excavators identified as “occupation zones”.
A Seriation Chronology for the Building r Site
The following table presents a seriation chronology for the Building r 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.