Comparing Assemblage Part 2

Yesterday, I introduced some of the work I’ve been doing with data from the Western Argolid Regional Project. I compared artifact assemblages from the same unit, but produced by two different methods: our standard survey field walking and more intensive 2 m radius total collection circles. 

As we have noted from similar experiments with the Pyla-Koutsopetria Archaeological Project, artifact densities produced by total collection circles tend to be significantly higher than those produced by standard survey. What remained less clear, however, is whether the larger number of artifacts recovered per square meter add significantly to what we know about the material on the surface or whether they mainly trade in redundant data.

More specifically, I was curious whether more intensive sampling of units with lower surface visibility might help us open a larger window into the assemblages present in the plow zone. This may seem more or less intuitive except that historically survey projects have tended to increase intensity in areas where more artifacts appear. Typically, projects employed more intensive collection strategies which ranged from gridded collection to total collection circles for areas designated as “sites.” 

To think about this, I compared pairs of units from the same area with different visibilities. For example, units 3420 and 3421 are from a large Roman site in the Lyrkeia Valley. Both units had above average artifact densities with 3420 having rather exceptional sherd densities (over 6000 sherds per hectare!) and the unit 3421 having high artifact densities (920 sherds per hectare). Unit 3421 has a visibility of 50% and unit 3420 was 80%. The areas selected for resurvey in both units had the visibility of 90%. They both had light background disturbance and compacted soils. The biggest difference between the two units is their size. 3420 is 2200 square meters and 3421 is smaller at 860 square meters. 

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The standard survey of 3420 produced 285 artifacts and the Resurvey 1 and 2 produced 83 and 115 respectively. The big spike in the standard survey line represents a gaggle of Early Roman amphora sherds turned up by the standard field walking. The slight hump in the blue line between 2600 BC and 2300 BC is from an EHII pithos sherd. Otherwise the profiles produced by the two types of survey are remarkable similar with the standard survey producing a bit more material datable to narrow periods.

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The results are largely the same from unit 3421. The most obvious difference, of course, is that Resurvey 2 produced 131 artifacts which is more than the 43 produced from standard survey and 79 from Resurvey 1. Despite the difference in quantity, the profiles is remarkably similar. Resurvey 1 recovered a small group of sherds of Bronze Age – Iron Age date leading to the orange line starting around 3200BC. The combination of material of Classical-Roman, Roman, and Late Roman dates recovered in Resurvey 2 produces the double-humped line that dominates this profile. The parallel, if lower lines, produced by the Resurvey 1 and Standard assemblages demonstrate that the increase in quantity adds little to the chronological range or distribution of material found in this unit.

Another case study produces somewhat different results. Comparing two units, 11027 and 11033 from the same area with lower visibilities, 40% and 30% respectively and slightly lower densities (which are nevertheless quite high for our survey area) of 207 sherds per hectare and 356 sherds per hectare respectively. 11027 has moderate background disturbance and 11033 has light and both have low vegetation and compacted soils. The biggest difference is unit size with 11027 being a positively massive unit for our survey at over 4800 square meters and 11033 being rather average with a size of 1684 square meters.

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The profiles produced by the various survey methods employed in unit 11027 are quite different. Standard survey produced an assemblage of 35 artifacts, while Resurvey 1 collected only 20. The assemblage from Resurvey 2, however, was 57 artifacts. The increase in material starting at around 1400 BC is driven by a single LHIII kitchen ware sherd and sustained by a robust, but rather undiagnostic collection of “Ancient Historic” (material dated to between 1050 BC and AD 700) semi-fine and kitchen wares that is paralleled at lower intensity by “Ancient Historic” material from Resurvey 2.  Both Resurvey 2 and Standard survey produced a spike in Late Roman and Roman utility and kitchen wares. Significantly, however, Resurvey 1 collected 3 sherds datable to the Archaic-Hellenistic period and material from these periods did not appear in the standard survey.

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Unit 11033 produced generally smaller assemblages with 23 sherds from Standard survey and 8 and 22 from Resurvey 1 and Resurvey 2 respectively. The major spike from Resurvey 1comes as a result of four semi-fine wares datable to the relatively narrow Early Roman period and is paralleled by a lower spike from the Standard survey. Resurvey 2 produced no other sherds datable to any period shorter than 1600 years! Resurvey 1 and the Standard survey produced some Classical-Hellenistic, Hellenistic-Roman, Roman, Late Roman, and as the late spike in blue shows, Medieval, Ottoman-Venetian material. The hump visible in the Resurvey 2 profile dating to around 450 BC represents a single Classical-Hellenistic fineware sherd and a collection of 13 semi-fine ware sherds dated to the rather broad Classical-Roman period. Despite the rather different profiles, then, the major patterns produced by diagnostic material are surprisingly similar between the two units.  

It is a bit tricky to generalize from two case studies, but the second pairing of units suggests that more intensive collection strategies when applied to units with low visibility but high artifact densities can produce additional chronological information from the units. In the first example in which visibility is higher, the Standard survey and resurvey profiles tend to be more similar.

Again, this is a very small case study, but it is suggestive that the traditional practice of increasing intensity in areas with high artifact densities (sometimes called “sites,” or euphemistically, “LOCAs” or “POSIs” or whatever) is less likely to produce new chronological information than a similar approach to units with lower surface visibility and correspondingly lower artifact densities. We did quite a bit of resurvey work in quite a few contexts across the WARP survey universe and by comparing the assemblages produced by different methods using Aoristic analysis, we should be able to test this hypothesis a good bit. 

It goes without saying that chronology is just one indicator of significance for artifacts collected over the course of survey. Variation in fabric, in function, and in shape also informs the analysis of surface assemblages and Aoristic analysis does not account for variation in these areas. At the same time, chronological continuity is the sine qua non for most analysis of survey material. If you can’t date material, then it is harder to make any historical arguments for it.

It is worth stating that this analysis is very preliminary and I am going to continue to tweak and firm up my formulas and the underlying data. And, we do plan on making all the data that supports this analysis available openly via Open Context

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