Understanding Artifact Distributions in Survey Archaeology

One of the things I’ve been working on for the last 2 (or 10 or 15) years is how do we understand the distribution of artifacts produced through intensive pedestrian survey. In fact, thinking about the distribution of artifacts and how our methods of survey and analysis shape the kinds of conclusions we can reach has been a major element in my career. 

For my current project, the Western Argolid Regional Project (and any of these survey really), there are a few obvious challenges. First, the basic spatial unit is the survey unit, but in our survey (and many surveys) these units are irregularly shaped and sized. Second, the units produce a good many interdependent variables that, in turn, shape artifact recovery. These range from surface visibility and vegetation to less obvious influences on site formation like terracing, ploughing, or various kinds of fills. Third, there are a good many variables that impact the distribution of artifacts that occur outside of what we can understand and record within the units themselves. These includes the presence of ephemeral paths and roads through an area, access to water or other changeable resources, the proximity to the edge of the survey area or highly disturbed units, and many other archaeological and historical features that might impact how we understand an artifact scatter.  Finally, we understand that various periods and types of artifacts have different levels of visibility in the landscape. This is the result of different historical processes that produce horizons visible on the surface as well as the character – and visibility – of the artifacts themselves.

In short, there are many variables that shape the distribution of artifacts on the surface and it’s hard to imagine a statistical model that would accommodate all these various.

There are, however, ways to start to smooth the distribution of artifacts and in an article that’s due in October, I’ve proposed the following method, which both attempts to produce understandable clusters of units with artifacts from the same period plotted across the landscape. These clusters are based on two measures of proximity between units with material from the same period: 20 m buffers and near analysis based on the “near” function in our project GIS. More important, however, this work is only the start. Because buffers and the near function do not adapt to changes in the landscape that range from steep slopes, modern roads, the course of the Inachos river, fenced plots, or the edge of our survey area, we need to scrutinize these simple clusters, particularly the discontinuities between clusters, to determine their historical and geographical probability. 

Here’s what I wrote:   

The following analysis is based on clusters of units from across he wider WARP survey area that produced Late Roman material. We identified groups of units on the basis of analysis done using the projects GIS platform, ESRI’s ArcGIS. We produced aggregated clusters of units by grouping any units that fell within a 20 m buffers of a unit with Late Roman pottery. We then assessed the relative isolation of the clusters using the “near” function in ESRI ArcGIS. Groups of clustered units that were statistically “near” one another could be aggregated further. Finally, we also allowed our familiarity with the topography of survey area to shape how we defined the clusters described below. Buffering, near analysis, and familiarity with the survey area helped to smooth some of the variations in surface visibility, local site formation, and recovery rates. These clusters also produced larger and more complex assemblages of artifacts than would appear in single or adjoining units, and these larger assemblages offered the opportunity for more nuanced reading of the material. These clusters, however, should not be confused with sites and their attendant assumptions regarding function or settlement rank. Instead, the larger assemblages allow us to retain the ambiguity inherent in the functional analysis of surface assemblage, while also constructing arguments for chronological and spatial differentiation at the scale of our survey area. 

Chelmis and Historical Archaeology in Greece

This fall, we received some really helpful reviews on an article that we submitted to the Journal fo Field Archaeology on our work documenting the Modern site of Chelmis in the Western Argolid. Among the comments was the suggestion that we develop the relationship between our work and historical archaeology more fully. Fortunately, I’ve been reading a good bit of historical archaeology over the past couple of years mostly for a project on the archaeology of the contemporary world. Below is my first effort to locate our work at Chelmis in this context. It’s rough, but very fun to write. 

First, historical archaeology has emphasized the impact of capitalism on our material environment. In fact, capitalism is one of Charles Orser’s famous “haunts” of historical archaeology along with colonialism, Eurocentrism, and modernity. While the archaeology of the modern Greek landscape remains in its infancy, there is a clear interest in how capitalism in both the recent past and in the 19th century shaped land use and settlement. [I blogged a bit on some related work yesterday, but one should include here Mark Groover’s survey of the archaeology of North American Farmsteads as well as his important work at the Gibbs farmstead as representative of the interest in capitalism.]  The famous “Contingent Countryside” of the Southern Argolid embodied the changing strategies of Greek communities as they adapted to the demands of regional and transregional markets. A. Vionis work in Boeotia has likewise recognized cycles of economic boom and bust in the Ottoman countryside that along with various political and environmental factors shaped the countryside in the 18th and 19th century. Changes in the furnishing of Greek houses, for example, paralleled the rise of Western bourgeois sensibilities that demonstrated both access to a wide range of middle class goods, capital to purchase these objects, and leisure time to enjoy small luxuries (Vionis 2012, 335-336).

The appearance of mass produced good in Chelmis, like milled nails and tools, aluminum pots and pans, and plastics, demonstrates this community’s changing relationship to markets, to the networks that supplied manufactured goods to the Greek countryside, and to rural practices. The relatively small assemblage of household goods, particularly ceramics, suggests that the buildings at Chelmis were primarily used for seasonal habitation prior to the appearance of mass produced goods at scale across the Greek countryside. A similar trend occurs throughout Western Europe and North America where the assemblages associated with the rural buildings change significantly in response to market penetration in the countryside.         

The study of settlement in the Greek countryside also represents an interest in the archaeology of rural settlement and the countryside that emerged in the UK and, to a less extent, in Western Europe. These studies are not necessarily separate from the longstanding interest in capital, but have tended to focus particularly on the role of modernity in shaping the use of the activity countryside. Chris Dalglish’s book, for example, focused on changes in rural life in Scotland brought about by various rural “improvement” programs of the 18th and 19th century. Charles Orser, on of the grand old dudes of historical archaeology, studied three Irish rural houses from the the same period and considered the changes to the rural landscape as part of the larger process of rationalizing the landscape. In fact, much of the work on the British landscape, as Matthew Johnson has unpacked, seeks to capture the relationship between the modern and premodern world in the countryside and understand not only the world that was lost but also the processes of change.

While the settlement at Chelmis is almost certainly later than many of the rural landscapes that underwent improvement, rationalization, and modernization in the 18th and 19th centuries in Britain, it nevertheless, was also shaped by efforts of the Greek state to transform the landscape. The development of settlements like Chelmis on land between the steeply terraced fields of the mountain villages and the fertile field of the Argive plain reflected efforts by the Greek government to encourage private ownership of formerly state lands. Transhumant pastoralists often developed these lands which were near their winter pastures and allowed themselves greater economy and social flexibility by creating relationships with villages on the plain. The end of season use of the settlement reflects several trends and policies as well. The decline of transhumant pastoralism in Greece, for example, which scholars have documented over the last 40 years reflects changing attitudes toward the movement of flocks through fields and toward the place of pastoralists in the economic and environmental life of the countryside. Mechanized agriculture has also changed the Greek rural landscape. It’s made temporary rural housing largely unnecessary and made it increasingly convenient for farmers to live full time in villages that also provided state and private amenities ranging from banks, to post offices, grocery stores, cafes, schools and government offices. Finally, urbanization and the inexorable draw of regional urban centers, like Argos and Nafplion, as well as Athens drew population from the countryside and away from rural life ways. 

These processes are not unique to Greece but the material evidence for these changing practices and relationships in the Greek countryside remains underrepresented in archaeological literature and rarely articulated in the context of either the broader fields of European (and particularly British) landscape and rural archaeology or (largely North American) landscape archaeology. Instead, there’s a particular strand of landscape archaeology in Greece which tend to look to Classical antiquity as its point of reference and contact, and this tends to imply a kind of continuity in the Greek countryside. At the same time, Greek scholars have a long standing interest in folkways, vernacular architecture, and historical studies of the countryside that often serves the development of national narratives. Our work at Chelmis is situated at the intersection of these analytical paradigms and also looks to historical and landscape archaeology to complicate our perspectives on the modern countryside. 

More Late Antiquity (or at least a start)

For the last week or so, I’ve been trying to get back into the academic groove and thinking about Late Antiquity. I have done some reading and, more importantly, some writing about the 7th century both in Greece and on Cyprus. Mostly, I’m working to get a first draft of a paper documenting and analyzing a 7th century site in the Western Argolid.

Here is the first draft of the first couple paragraphs. It’s rough, lacks citations, and I’m sure it’ll change, but at least it’s going somewhere.

The past two decades have witnessed a major change in how archaeologists understand the Late Roman and Early Medieval landscape of Greece. The rise of survey archaeology in the late-20th century fueled the growing awareness of the “busy countryside” of Late Antiquity. This complemented work in urban areas across Greece and the Eastern Mediterranean more broadly demonstrating that Late Roman cities and their countrysides experienced continued prosperity, social vitality, and political and economic significance into the 5th and 6th centuries. For Greece, scholars argued that the Slavic invasions of the late-6th century brought an end to this Late Antique prosperity and initiated a period of economic, political, and social dislocation often called the “Dark Ages.” Over the last 20 years, work at urban and rural sites has started to question this narrative. Work at the site of Corinth, in particular, has shown that the city continued to prosper into the 7th century. Moreover, imported ceramics and storage vessels indicate that Corinth enjoyed persistent connections across the Mediterranean even if these connections appear to be less dynamic and consistent then earlier centuries. At the same time, regional networks in the northeastern Peloponnesus emerged that supplied cooking and utility wares to communities well into the final third of the 7th century. The results from Corinth suggest that the city experienced economic change in the 7th century with fewer imports and a rise in regionally produced vessels, but this change was not the same as decline and indicated continuity with earlier centuries as much as new patters of economic and social relations.

Stratigraphic excavations formed the basis for this revised assessment of the 7th century in Greece. The assemblages produced through excavations at Corinth and at the Pyrgouthi Tower near Berbati in the Argolid, in particular, have helped to revise the dates of earlier excavation across Greece and challenged the assumption that destruction deposits associated with the Slavic invasions should have 6th century dates. Deposits from the Baths at Argos and the Stadium at Nemea, for example, now are better dated to the 7th century than to the later 6th century as their original excavators suggested. This revised chronology has also extended to our analysis of intensive survey assemblages. For example, pushing the date of certain well-know finewares into the late-6th and early-7th century Phocaean Ware 10C and the later forms of African Red Slip (105 and 106) illuminates areas of possible 7th century activity in the Eastern Korinthia Archaeological Survey area (Pettegrew 2007, 777; Caraher 2014, 157-158). In other contexts, Chris Cloke’s study of the off-site material from the Nemea Valley Archaeological Project has revealed a 7th century landscape with remarkable continuity with material from the 5th and 6th centuries. This article takes Cloke’s assessment of 7th-century landscape of the Nemea Valley and work at Corinth and considers it in the context of recent work in the Western Argolid Regional Project (WARP).

Formation Processes and Peter of Argos


This summer, Dimitri Nakassis, Scott Gallimore, and I along with a some remarkable graduate students continued to work our way through the data from the Western Argolid Regional Project. Yesterday, Dimitri published a little blog post that expressed a good bit of our frustration with interpreting our data. In some ways, his post expresses some of the same ideas that I tried to work through with “Slow Archaeology.” Analyzing survey data is hard.

For WARP, the challenge stems, in part, from the quantity of data that we produced as well as the fit between what we anticipated (and how this shaped our data collection processes) and what we found on the ground. There is always some risk that the tension between how we collected data and the structure of our databases may obscure the historical and archaeological processes that led to the distribution of material across our survey area. For example, we know that certain areas in our survey produced very few artifacts, but it’s so far been hard to determine whether this reflects an ancient reality (i.e. limited activities), natural processes (e.g. erosion or other depositional events), or a modern field conditions (i.e. surface visibility, plowing, imported soils, et c.). In this situation, we have tried to understand the combination of variables that characterizes low-density artifact scatters in a generalizable way without undermining the possibility that low-density scatters are produced through a wide range of processes. Difficulties of this kind are not unique to our project or survey archaeology, but are fundamental to any effort that takes into account formation processes.

I’ve also read Anthony Kaldellis’s new translation of Ioannis Polemis edition of the Life of Peter of Argos in their Saints of Ninth- and Tenth-Century Greece. One of my favorite stories involves the battle between Argos and Nauplion over the body of St. Peter of Argos. It think there’s a lesson in this for all of us (I’m not sure what that lesson is):

Life of Peter of Argos, Chapter 14

Then a quarrel broke out between the citizens of Argos and those of Nauplion, as the latter wanted to carry the blessed relic into their own town and transfer it to Nauplion. They even drew weapons, but their rush was checked by the multitude of inhabitants of Argos. So they yielded unwillingly and failed in their purpose.

Methana

I’m notorious for struggling to take time off during the summer. This not only damages my ability to work efficiently, but also makes me tired, impatient, and generally grumpy. This summer, I was well on my way to being a big ole grumpy pants and stumbling and bumbling to the end of our study season on the Western Argolid Regional Project. 

But then Fotini Kondyli invited me and Dimitri Nakassis to her family’s home on Methana for a day. It was relaxing and beautiful.

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Typologies

The storerooms where we work at the Western Argolid Regional Project have a set of cabinets where we store artifacts. Apparently these cabinets came from the French project in Argos and were passed on to our project when they were no longer used.

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One of the most charming things about these cabinets is that the drawers have different handles on them. I suppose they installed simply what was inexpensive and available at the time. Some appear to be replacements maybe after a handle broke or perhaps some drawers only got handles when they were filled with artifacts.

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Landscapes of the Western Argolid

It’s taken me about five years to wrap my head around the landscapes of the Western Argolid. It feel like one of those crazy Möbius strips where space bends back onto itself and opposite points end up being on the same plane.

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Part of the challenge is that I’ve spent so much time looking down or wending my way through hillside maquis that I overlooked the larger topography of the region. Fortunately, this summer, I’ve spent a good bit of time looking at maps, analyzing viewsheds, and then ground truthing them in the field. Not only has that helped me make better sense of the landscape, but it has also given me a greater appreciation for where I’ve worked for the last five years.

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A Visit from the E-Curators Team and Digital Time

Yesterday, Costis Dallas and Seamus Ross from the E-Curators project visited the  Western Argolid Regional Project study season to talk to us about our use of digital tools and digital practices. We spent most of the day in either formal interviews or informal conversations about how we used technology to produce know on WARP from the practices of our field teams to our analysis and plans for archiving, publishing, and disseminating our datasets. The conversations were honest, practical, and balanced between a formal script and a casual conversation. The interview was part of a larger collaborative project to document digital practices among archaeologists in the field and in their interpretative strategies.

The interviews offered a chance for me and Dimitri Nakassis to reflect on not only how we used digital tools, but the larger strategies that we employed to collect information in the field, how we converted this information to data, and how we analyzed this data. The most revealing thing was how much, in hindsight, we relied on the shared expectations and understandings with our remarkable team leaders. Our team leaders ensured that the information collected in the field was rigorous and consistent, but also managed the day-to-day functioning of the project from making maps to guide their teams to deciding which team would survey which fields.

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One of the simple pleasures of field work is revisiting sites. This week we returned to a small tower at the site of Ay. Dimitrios that stands in a pass that leads into the Inachos Valley. 

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We flew the drone for the third time at the site and have worked to refine our technique for creating highly accurate orthomosaics (<.20 m) of sites for illustration and study. Needless to say, flying the drone is not overly technical, but it takes time and is pretty boring. The third time, in particular, is tedious and probably is the tipping point in terms of using newfangled tools to do things quicker and more efficiently. We probably could have drawn the dang thing in about 8 hours.

I mentioned this idly on Twitter and got the usual round of fascinating responses. As part of my new, more relaxed, Caraher 3.0 reimagining, I sort of regret posting something about this on The Twitters, but I will say that I don’t think that there’s much of a difference in the traditional output between a hand drawn top-plan on site and one produced through dronoscopy. Maybe some bleeding edge publications could host a 3D model of the site based on structure-from-motion images produced from our drone photos, but these kinds of publications are relatively few and far between. Hand drawn plans remain the standard form of publishing fortifications in Greece. The drone images offer a more robust dataset for the future, but most archaeology – for better or for worse – focuses on documentation methods geared toward the now.

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Chatting all day with the E-Curators folks, I came to appreciate the links between how we worked and sometimes unconscious or at least unarticulated ideas of outcomes. These outcomes are mostly conventional and it becomes easy to fall back on conventional practices as a result. Changing the kind of outcomes that we expect from archaeological work – whether its in terms of dissemination or the kinds of knowledge produced – will invariably change the social organization and technologies that we use. 

Diagnostic Ceramics and WARP

One of the nice things about a study season is that there is time to do little studies that can get lost in the bustle of a field season. There’s also time to catch up on some reading that all too easily gets set aside during the academic year.

This week, for example, I spent some time with a recent article by Elizabeth Murphy and collaborators in the most recent JFA (2019) (and here) Since we’re working on a preliminary report for WARP, it was useful to read how another project introduced their work, their methods, and their goals. More specifically, however, Murphy and her collaborators offered some insights into a collection strategy that was markedly different from ours at WARP.  The LASS project in Sardinia counted 19,176 artifacts and collected 1371. In other words, 7.1% of the seen artifacts were diagnostic (7). This likely speaks to the relatively poor state of ceramics knowledge for Sardinia and what defines an artifact as “diagnostic” than any shortcomings of method on the part of the LASS team.

In contrast, WARP had the advantage of working in the general vicinity of a large number of well-know and thoroughly excavated sites (in varying degrees of publication) that helped us expand what we regarded as diagnostic. This also complemented a rather robust sampling strategy which provided us with a large assemblage of material for analysis. Here’s a short study that considers the significance of our collection strategy in the context of ceramic knowledge in the larger WARP region. 

At WARP, over the course of standard transect walking, we counted 119,414 artifacts including sherds, tiles, lithics, and “other”. We collected 64,983 artifacts or 54.4% of all the artifacts seen. This was consistent with a sampling strategy that asked field walkers to collect all visible sherds, but to sample only unique examples of tiles on the basis of fabric and part of the tile (e.g. edge). In the end, we collected 39% of the tiles that we counted. Considering that 78% of the collected tile was either chronologically undiagnostic (what we called “Tile, Ancient Historic”), Modern, or Early Modern, this seems like a good decision.

A cursory statistical review of the collected artifacts likewise demonstrates that a more robust sampling strategy of each survey unit produced archaeologically significant results. While the definition of “diagnostic” pottery is largely in the eye of the field walker and ceramics experts, rims, bases, and handles (RBH) are almost universally recognized as potentially diagnostic and almost always collected. For WARP, these accounted for approximately 10% of the artifacts collected during typical field walking. The remaining 88.9% of the material were body sherds. During revisits to units where we collected more intensively over a more limited area, we produced assemblages that were 87.8% body sherds and 12.2% RBH. This suggests that the sample produced through regular field walking reflected the percentages of material in the plowzone. Interestingly, we also told our teams that they should collect any material from their units that they thought might be diagnostic, but did not fall into a swath, and designate this material as a “Grab” sample. We also designated as “grab” any material from units that we did not survey using our standard survey methods including amid the collapse of Early Modern houses and the overgrown and rocky acropolis of Orneai. These grab samples were 83.6% body sherds. When we filtered out tiles from this assemblages, which produce a large number of body sherds and appeared in an almost continuous carpet across our survey area, the percentages remained more or less the same. For standard survey, 78.9% of our sherds were body sherds, for more intensive resurvey, 81.7%, and for grabs, 77.7%

Of course, most surveys – including LASS – recognize that decorated body sherds are diagnostic. Like most surveys, WARP found that only about 9.3% of our body sherds preserved decoration. Of these decorated sherds, about 45% of them could be dated to a period more narrow than 1000 years. What’s more remarkable, however, is that of the 90% of our body sherds that lacked decoration, 33% of these sherds could also be dated to a narrow period on the basis of preserved shape or fabric. For grab samples, which are by definition more diagnostic, our ability to data undecorated pottery to less than 1000 years improves to 67.1% which is not far from the 72.6% for decorated sherds.

For some periods, like EHIII, Classical-Hellenistic, Hellenistic, and Roman and Late Roman, undecorated body sherds far outnumber decorated body sherds. As a result, a collection strategy that overlooked these sherds would have significantly biased our view of the landscape.

Quick Thoughts on Open Access

Over the past week I’ve been thinking a good bit about publishing and disseminating archaeological data and yesterday I had some thoughtful conversations with Becky Seifried who was fresh from a recent conference in Athens on the topic (pdf).

I don’t really have anything profound to say about data except the observation that for archaeological projects, the more stakeholders involved, the harder it is to determine how best to disseminate project data. On the one hand, it is easy enough to envision how open data will allow our data savvy community to “dig into” the results of our field work. Moreover, those of us publishing both data and analysis of our projects can understand the value of making the link – no mater how fuzzy – between field work and interpretation clear. In fact, our field increasingly embraces this kind of transparency and openness as both a way to allow researchers and communities to engage with what passes as “raw material” in archaeology.

At the same time, we also recognize the rights of communities to control their own pasts and realize that the past – and its material and digital surrogates in the present – operates within diverse spatial, political, economic, social, and discursive regimes. As a result, openness in data can at the same time be decolonizing and colonizing, progressive and regressive, and collaborative and “going rogue” all at the same time. In fact, the more stakeholders invested in the data and the work, the more openness is seen as a challenge especially among communities who already feel that their control of their own past is vulnerable. 

What’s interesting, of course, is that we often position open, digital heritage as a way to engage more diverse communities in the process of understanding their own past. For archaeology, sharing archaeological data invariably engages those who want to use public data for personal gain (e.g. looters), those who see the digital surrogates of archaeological objects as deserving the same protections as the objects themselves (e.g. limited or highly curated access), and those who see the tools necessary for digital dissemination of archaeological data as a barrier to access.

I recognize that people have thought seriously and expansively about the challenges  of open publishing and digital heritage in practical and theoretical terms. I tend to be so deeply immersed in the data themselves (and the processes of moving data from the survey unit to the final database) to think very hard about these issues. It’s only now as parts of our dataset has taken on its final shape that I’ve had reason to think about its open or not so open after life.