This week, I’m continuing to work on producing a preliminary report for the Western Argolid Regional Project. One of the particular challenges in writing a report is the tension between the granularity of our survey data and the size and complexity of our survey area. As a project committed to conducting siteless, “artifact-level” survey, field walkers spaced 10 m apart collected all artifacts visible on the surface from their 2 m wide swaths. These artifacts were all analyzed and given a chronological range, a functional category, and, whenever possible, a place within existing artifact typologies. At the same time, we also counted each visible artifact using a clicker counter allowing us to have an almost instant assessment of the quantity of sherds present in each walker’s swath and each unit. We recorded this data, along with basic environmental data collected from each unit, on a survey form that we then entered into the project database and projected into our project’s GIS.
In a traditional intensive survey, artifact densities serve as an indicator of sites in the landscape. These projects then documented these sites with a different level of intensity usually through gridded collection or some other more spatially rigorous sampling strategy. This allowed survey projects to distinguish the assemblages produced by these “on site” practices from those produced by “off site” survey practices which generally involve larger transects and less intensive sampling regimens.
Artifact level survey, in contrast, tends to emphasize a consistent method for sampling the landscape, in part, because they recognize the complexities of site formation in the landscape and approach any definition of a site with skepticism. In fact, my colleagues and I argued over a decade ago that many sites in the Corinthian represented the complex interplay of assemblages from multiple periods rather than a single “multi-period” site with recognizable continuity in activity. In this context, then, overall artifact densities offer only the coarsest indication of activity in the landscape or, worse, are illusory when they occur only when the edges of unrelated, narrow-period scatters overlap. A growing awareness of geomorphological and geological processes, varying levels of artifact visibility, and changing vegetation, the presence of background disturbances and the character of the surface clast, further complicate any argument that high density sites produce meaning in the landscape.
As this approach to intensive survey fundamentally questions the value of artifact densities as the basis for the historical analysis fo the landscape, are artifact densities meaningful in siteless survey?
As I work on the WARP preliminary report, I argue that they are for three reasons. First, artifact densities do provide a measure of artifact recovery rates from a particular unit especially when combined with surface conditions like visibility. A unit that produces a high artifact densities in relation to visibility is probably a unit with a significant quantity of material obscured by the independent vagaries of surface conditions. Knowing this kind of information, for example, allows us to consider more carefully issues like the extent and continuity of an artifact scatter datable to a particular period. While we may not be able to control for all the site formation processes that shape a context as complex as the surface, we can sometimes control for the variables that impact artifact recovery from the plowzone.
The second advantage of collecting density data for intensive survey is that it provides a context to measure the diversity of the assemblage present in a unit. We recognized in studying data from the Eastern Korinthia Archaeological Survey that the chronological and functional diversity of an assemblage tends to increase with artifact densities. In other words, we had very few examples of units where a single period – or even artifact type (think: modern tiles) – increased artifact densities in a significant way. We then applied this realization to lower density units that often result from compromised surface visibility or other conditions. In these contexts, we discovered that some units with low artifact density tend to produce more diverse assemblages than others. These high diversity, low density units may provide windows into more complex scatters that the vagaries of surface conditions and site formation obscured.
Finally, artifact densities do provide insights into large-scale, diachronic patterns in the landscape. Diachronic intensively survey has some chronological challenges in that artifact level survey tends to push us to fragment the landscape into the finest periods possible. In some cases, these periods are quite narrow (final decades of the 4th century) and in other cases quite broad (Medieval or Classical-Roman). The broadest and narrowest periods create some challenges of commensurability as they tend to produce vastly different meanings in the landscape. A narrowly dated artifact, for example, might well represent a particular activity – such as a funeral practices or household activities – whereas a broadly dated artifact tend to represent broader and more persistently uniform functional categories: storage or roofing. Understanding the relationship, then, between landscapes defined by narrower chronological (and usually functional) categories and and those defined by more broad categories is difficult and always risks stripping from countryside the temporal aspect of persistent activities while pocking it with episodic behaviors tied closely to more precisely datable artifacts. Total artifact densities offer a big picture way to see human activity in all its complexity and consistency across the landscape. These densities must, of course, be read critically and contextually, but that’s true of all archaeological evidence.