Some Notes on RBHS Analysis of the Pyla-Koutsopetria Survey Data

No RBHS is not a local high-school to whom I've outsourced PKAP data analysis, nor is it a new type of digital hi-def television.  Those letters stand for Rim, base, handle, sherd and represent the basic parts of a ceramic vessel.  Since most of the vessels one finds in survey and even excavation are not whole or are broken and mangled, documenting the rim, base, handle, and sherds from each vessel is an important way to understand how we as archaeologists are able to identify an particular object and assign it to a date, function, and even, sometimes, place of manufacture. It is also helpful in secure, stratigraphic contexts (that not in an unstratified survey context) for identifying the minimum number of possible vessels of a particular type because we know that some kinds of vessels on have, say, one-handle, then a four handles would represent at least four vessels of this type.

David Pettegrew's research has really set the stage for applying this kind of analysis to the PKAP survey data. He has argued that certainly highly diagnostic artifact types (for example Late Roman 1 amphora handles or Late Roman "combed ware" body sherds) can distort the chronological distribution of material at a site.  Periods characterized by less diagnostic artifact types tend to be less easily associated with a narrow chronology or function and under represented in relation to period defined by more easily identified vessels types.  So isolating the way in which particular periods become visible using our Rim/Base/Handle/Sherd analysis becomes an important to critique our survey data.

Fortunately, the basic system that we use to document our ceramics, the chronotype system, took into account rbhs. The chronotype system required the ceramicist to separate and document as a group, called a batch, according the extant part of each type of vessel present . In other words, we counted in one batch all of the rims from, say, a Roman Amphora and in another batch all the handles from the same kind of amphora. This has allowed us to parse quite finely the character of our assemblages and its relationship to our ability to identify particular types of artifacts based on their individual parts.

So here are some basic observations:

• Of the 19 periods with more than 20 sherds collected using our standard survey procedure, 13 counted the majority of artifacts as body sherds. In other words, for most periods, body sherds represent both the most common and the most chronologically diagnostic type of material.
• Only for the Archaic period were the majority of artifacts identified by one part of a vessel, and these almost all came from one type of vessel, so-called Archaic basket handled storage jars.
• Of the 258 chronotype (that is discrete types of artifacts) that produced extant parts (some chronotypes, like shells or wall plaster fragments, do not produce extant parts that we can easily record), 138 of 55% of these chronotypes were identifiable based on only one extant part. 76% are recognized by only two extant parts and 90% by three. 99% by four extant parts (mainly RBHS).  In other words, most artifacts are only recognizable by one part of the vessel.
• It is interesting to note that the number of chronotypes associated with a particular period has almost no influence on the average number of extant parts by which a vessel is identified. Large number of chronotypes identifiable by a large number of extant parts (4+) come from Roman (40), Late Bronze Age-Hellenistic (18), Ancient Historic (39), Hellenistic-Early Roman (24) vessels. At the same time 4 or more extant parts also appeared for periods with fewer chronotypes, like Classical-Roman (6), Late-Cypriot II-Late Cypriot III (4), and Post-Prehistoric (4).  This means that while the majority of sherds from each period are body sherds, they nevertheless have vessels that are identifiable based on other parts of the artifact.  In other words, our ability to date artifacts to a particular period is independent from the number of vessels with identifiable extent parts. Some periods have three or four chronotypes with lots of identifiable fragments; others have 25 different chronotypes with a mix more and less easily identifiable artifact types.  There does not seem to be a pattern.
• Far more central to the number of parts of the vessel that we can identify is the kind of vessel and their function. Kitchen/Cooking ware produce the most possible extant parts (4+) followed by coarse ware and amphora chronotypes (3.8). Medium coarse ware produced 3.5, while pithos, semi-fine, and fine all produced 2.4 or fewer extant parts per chronotype. This likely has more to do with the shapes of the vessel than the size of the vessel.

This kind of analysis may seem tedious and complicated, but it is important to understand how bias in our ability to identify a particular type of artifact can influence the kinds of chronological and functional landscapes that we create from survey data.  In examining our data in this way, we can really see the point of contact between what our ceramicist does in placing artifacts in particular classes and our historical reconstructions of the landscape.  The entire world of Pyla-Koutsopetria is literally born from the data gleaned from individual artifacts.