Last week, I looked at surface visibility and artifact densities. This week, I want to look at two issues when considering the analysis of distributional data across the Pyla-Koustopetria Archaeological Project's study area.
First, the distribution of ceramic material and the topography of our site recommend that we divide our site into zones for analysis. I decided to divide the survey area into zones to attempt to isolate some variables influencing the distribution of material across the site. In particular, these zones capture areas with distinct patterns and levels of artifacts. Zone 1 -- the area around Koutsopetria -- has a ceramic density of over 4000 artifacts per hectare. Zone 2 -- the coastal plain to the east of Koutsopetria -- has an overall artifact density of barely 700 artifacts per hectare. Beyond that the areas capture very different environmental conditions. Zone 1 consists largely of grain stubble fields with an average visibility of around 48%; Zone 2 units are usually sandier soils only a few of which are under cultivation. The average density in Zone 2 is over 70%. Zones 3 and 4 are defined as much by topography as by artifact densities. Zone 3 centers on the prehistoric site of Kokkinokremos and featured units shaped to take into account the plowed top and unplowed slopes of this. Zone 4 is the top of the Kazama ridge which extended north from the height of Vigla. I have isolate Vigla from any zone since the densities there were so high and the environmental conditions in that hill were distinct.
Despite the fact that these zones are the creation the archaeologist and archaeological methods, they nevertheless provide a way to limit some of the known variables (significant variations in artifact density, for example, or clear differences in land use or environmental conditions) in order to isolate other variables which may have had locally significant influences on the distribution of artifacts. Of course, this assumes that the characteristics that formed the basis for the zones are not the main factors on our ability to map ceramics across the survey area.
To test that I isolated a number of variables that we have seen influencing our ability to document the material on the surface and look at whether they coincided with the zone divisions.
First, I mapped the distribution of grain stubble fields across the site. Grain stubble can be the survey archaeologist's worst nightmare as it typically accompanies the remains of cute wheat which can obscure the surface of the ground almost entirely. The darker units had grain stubble.
In units without grain stubble there was frequently some standing vegetation. We recorded the height of standing vegetation across the entire survey area. The darker the color the higher the vegetation. Note that the height of the vegetation doesn't influence visibility in a predictable way. Sometimes waist height vegetation actually makes the surface easier to see.
Another factor that plays into the distribution of ceramics is whether the fields show signs of recent plowing. The plow often bring material to the surface from deeper with the plow-zone, but it can introduce background disturbance (see below) and break pottery into small fragments that increase the number of artifacts without increasing the amount of material (say, by weight) in the unit. At the same time, it tends to limit vegetation across the area. The darker areas are plowed fields.
I also mapped background disturbance across the zones. Background disturbance is a survey archaeology term that describes the amount of non-archaeological material in the surface soil that confuses the eye of the archaeologist. The most common form of background disturbance are fragments of bedrock chipped by the plow and turned into the soil. This material often looks like pottery and makes identifying ceramic material in the soil more difficult. Some analyses of the data from the Eastern Korinthia Archaeological Survey has suggested that background disturbance often influenced the ability of fieldwalkers to document material on the ground to a considerable degree. The darker the color the more background disturbance there was recorded. Note the consistent moderate to heavy background disturbance across Zone 4.
These basic environmental characteristics can now be compared to artifact distribution both across the site and in the individual zones. Stay tuned for more!
For more Thinking Out Loud see: