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A Comparison Between a Survey Assemblage and an Excavation Assemblage

November 2, 2010 Leave a comment

For the past few months, David Pettegrew and I have been “publishing” the preliminary results of some experimental analysis conducted over the past year at the Pyla-Koutsopetria Archaeological Project on Cyprus.  As part of the experimental component to our project we were interested in documenting the relationship between the surface assemblage and the assemblage of material produced by excxavation

The archaeological fieldwork conducted on the elevated height of Vigla provided us with an opportunity to compare assemblages produced by intensive pedestrian survey and the excavation of a trench in the survey area.

Longstanding critiques of survey have suggested that the relationship between the surface assemblage and the subsurface material is too problematic for survey to be a technique used to produce a comprehensive view of the landscape. While it is true that there are more variables in the formation processes that impact the creation of a surface assemblage, we should be aware of the potential for a false dichotomy. Excavated assemblages are every bit as much a product of formation processes as those on the surface and as a result, we always have to temper our interpretation of past events with the understanding of the archaeological record as the product of a whole range of physical and cultural transformations. The goal of this comparison then is not to test the surface assemblage against the subsurface material, but rather to suggest that their correspondence indicates that the area may have endured similar archaeological processes.

As with all of our experimental units, the comparison is influenced by significant differences in the spatial comparison between the two sample areas. The surface area of our trench EU 8 represented only 6 sq meters; The two survey units 500 and 500.1 combined to covere over 6000 sq m. Any comparison of area, however, is problematic; the trench had volume and the relatively two-dimensional surface of the survey area did not.

SurveyAndExcavation  

The excavation unit produced significantly more ceramic material. The excavation unit produced over 4000 artifacts. By comparison, we counted anywhere from 366 to close to 1000 artifacts from our survey of various areas on the top of Vigla (depending on surface conditions and the number of walkers available), and these samples allowed us to estimate an overall artifact density of between 15,000 – 11,000 artifacts per ha. These are astronomical densities by any reckoning.

While we counted every artifact visible in our 20% sample of the surface, we collected artifacts using the chronotype sampling strategy which required us only to collect each unique type of sherd from each swath.  Using this technique in two campaigns of field walking on Vigla, we collected 963 artifacts with a weight of 27.6 kg.  In contrast, we collected and analyzed every artifact from the excavation area and this resulted in over 4000 artifacts, but this assemblage weighed less than 10 kgs more (37.0 kg) than the assemblage collected from survey.

The nature of the chronotype sampling method used in the survey makes it difficult to find a metric to compare the quantity of material collected from the survey against the quantity of material collected from excavated contexts. The key point for evaluating the correspondence between the two assemblages is not necessarily the quantities of material but rather the presence or absence of material indicating particular activity, periods, or material types present in the area.

Comparing the period date between the two collection strategies reveals that the survey collection produced more chronotype period categories (16 compared to 14) and nine of the periods represented in the survey assemblage were also represented in the excavation assemblage. In general, the survey material represented a longer chronological range with material from later periods present on the surface including material from the Late Roman, Medieval-Modern, and Modern periods. The excavated area, in contrast, produced more material from narrower periods and at least one object from a period earlier than those represented in the survey, a sherd potentially dating to the Bronze Age (for more on broad and narrow periods, see here). This artifact appears to pre-date the earliest phases of architecture present in our trenches and may not represent a past activity on the site. In general, the material from both the survey and the excavation overlap, but the excavation material offered slightly more chronological resolution than the material from the survey.

The diversity of chronological periods in the survey material would appear to extend to the chronotypes represented in each unit. The excavation produced 54 chronotypes, while the survey unit produced 57. There are 30 overlapping chronotypes between the two collection methods. While the different sampling techniques make it difficult to compare the assemblages in a meaningful way, the quantity of material from each area nevertheless provides a very basic matrix for comparing the relative quantity of various types of material from each unit. The survey and excavation both produce a significant number of artifacts from the three rather general chronotypes: ‘Coarse ware, ancient historic’, ‘medium coarse ware ancient historic’, ‘kitchen ware ancient historic’.  The excavation also produced a significant proportion of material from two additional chronotype that were poorly represented in the surface assemblage: ‘animal bone’ and ‘fineware, Hellenistic-Roman, Early’ which made up 6.6% and 5.5% of the excavated material respectively, but less than 1% of the material from the survey. The absence of animal bone on the surface of the ground could be an issue with visibility (white and tan bones do not stand out as well against the buff colored soil) and certainly preservation. 

It is notably harder to compare the potential range of activities present in the area. The chronotype method of collection privileges larger, better preserved sherds (walkers will often discard small or poorly preserved sherds if they find larger examples of the same chronotype). It also tends to under represent very common chronotypes in proportion to the total assemblage. In other words, there are fewer examples of chronotypes such as “medium coarse body sherd, ancient historic” in the survey sample in part because field walkers were instructed not collect multiple examples of this very common type of artifact. In the excavation, excavators collected every example of a “medium coarse body sherd ancient-historic” causing sherds of this type to make up a larger proportion of the total assemblage.

This tendency can be seen in the relative size of artifacts collected from the survey and excavation. From the survey, the collected artifacts were much larger and this probably reflects both our field walkers’ tendency to select larger sherds more frequently than smaller sherds for collection and the difficulty seeing the smallest sherds on the ground from a standing posture. These two tendencies combined to produce an average survey artifact weight almost 30 g as compared to the average size of an excavation sherd that was under 9 g.

The fabric groups present show some significant differences in the assemblage that we can largely trace to different sampling strategies. The survey unit preserved more coarse ware
(47%) whereas the majority of material from the excavated unit was medium coarse ware. The weight of the two fabric groups as a percent of the total assemblage sheds more light on the situation. Medium Coarse wares from the excavation represented 53% by volume, but only 22% of the assemblage by weight. In fact, the average weight of a medium coarse ware sherd is less than 4 grams. In other words, many of the medium coarse fragments of pottery from the excavation are quite small, and these sherds are the most likely to be overlooked during survey. Cooking/kitchen ware, coarse ware, and amphora represented the other significant parts of the excavation assemblage. As the chart below indicates the percentage of weight is significantly different from the proportions determined by counts. In weight amphora and coarse wares combine to make up the majority of material.

image

The material from survey shows different proportion, but these proportions are significantly biased by our sampling technique that suppressed the collection of redundant artifacts.

image

Coarse ware is the most common fabric group by quantity and makes up the majority of material by weight. Amphora sherds, which tended to be handles or very large body sherds, represent a massive quantity by weight, but significantly lower percentage by quantity. The opposite is true of medium coarse ware and kitchen/cooking ware.

Similar tendencies are visible from rim-base-handle-sherd analysis (for more on R-B-H-S Analysis, see here). 

image

The results of this comparison suggest that for the height of Vigla the most major differences between the assemblage produced by survey and that produced by excavation are tied to the different sampling strategies used in these different contexts. At the same time, the basic patterns present in the survey assemblage were also present in the assemblage from the excavation.  The presence of material from the Classical and Hellenistic period, the presence of fine ware, kitchen/cooking ware, and utility wares, and the almost complete absence of earlier material allows us to argue that the site was first occupied in the Archaic to Classical period, saw domestic activities, and then was used less intensively in later periods.  This close correlation of survey and excavation assemblages reflects, in part, the stability of the soils on Vigla and the relative lack of erosion, on the one hand, and the lack of intensive activity during later periods, on the other.  In other words, the surface assemblage and excavation assemblage enjoyed similar sets of formation processes which produced similar assemblages. 

Hesperia, Offprints, and the American School

October 26, 2010 7 comments

Yesterday I had one of those little thought-provoking coincidences that make you wonder about how things could be done better.

At 11:44 am I got an email from the American School of Classical Studies publication office concerning our soon-to-be-published article on fortification around Ano Vayia.  Our article will appear in the next issue of the American School’s journal, Hesperia. The email asked us where we would like our 50 complimentary offprints sent and whether we wanted to purchase 50 more for $150. Hesperia offprints are really lovely things. They are stapled, on high quality paper, impeccably edited, stylish in design, and include a nice, glossy cover.  In short, the $150 price for 50 does not seem unreasonable.

At 1:45 pm that same day I received a form-email from Jack Davis, the Director of the American School of Classical Studies. It was their annual fund-raising email.  The American School of Classical Studies at Athens is one of my favorite things in the world.  The institution played a key role in anything that is good about my professional development and no matter how long I am away, still has the feeling of a home-away-from-home. I have benefited three times over from their generous fellowships and these fellowships have led to my dissertation and numerous publications. I have come to appreciation the American School for its awkward and paradoxical blend of things traditional and things contemporary and “modern”. By not shying away from some of the most traditional aspects of a classical education (e.g. the flavor of the Grand Tour that pervades the Regular Program), the School encourages students to reflect on the practices and institutions that have created the disciplines of Classics, Classical Archaeology, Ancient History, et c.  Because of these things, I am in the habit of giving money to the American School.  I can’t give much as an Assistant Professor at a state school in North Dakota, but I give my proverbial widow’s mite.

Back to the coincidence: In the same day, within hours, the same institution that was asking for money also offered me that very day something for free.  This got me to think: what if we as contributors to Hesperia just turned down our offprints?  Now, I recognize that the circulation of offprints continues to play a small role in the “academic gift economy”.  But, as I began to try to make a mental list of people to whom I’d like to send offprints, I was counting far fewer than 50 individuals.  Moreover, many of the people on that list would probably just as soon have a digital offprint (a handsomely formatted .pdf file) suitably disgraced with some personal note of thanks. The digital offprints of Hesperia are every bit as high quality as the print offprints with good resolution on photographs and searchable text.  Moreover, of the handful of people to whom I’d send offprints, almost all of them have access to Hesperia.  Less than a month ago I had a conversation with a resolutely “olde skool” American School type and offered to send him an offprint of my forthcoming article. He smiled, thanked me, and said, that he subscribes to Hesperia. (I knew this, of course, but apparently even among the “olde skool” the ritual component of offprint exchange had fallen into disuse.)

All the same, I can anticipate some people saying that some individuals still keep paper offprint files and some of our European colleagues take the circulation of paper offprints quite seriously and some offprints serve as valuable contributions to small, highly specialized and underfunded libraries (say at the local office of the archaeological service).  The high quality of a Hesperia offprint makes them almost something of intrinsic value.

On the other hand, I am pretty sure (although I won’t admit to doing this) that we can still print out a copy of a Hesperia article, scrawl some heartfelt note of thanks of the first page, and present it to a colleague as a token of thanks.  Maybe this violates copyright?  I’m really not sure, but I can hardly imagine this to be the kind of practice that the International Copyright Police would enforce, and it would guess that it would be possible for Hesperia to give authors permission to reproduce a certain number of copies of their own articles. (Although it would be awesome to be approached by a neatly dressed Nigerian man outside the Agora in Athens with a stack of slightly blurry photocopied Hesperia offprints…).

One more thing, Hesperia offers to let us purchase another 50 offprints for $150. Since Hesperia articles tend toward the long side, I assume that this price represents the average cost of printing 50 offprints, perhaps with some small compensation of watering down the copyright (in other words, perhaps they factor in that some people will receive an offprint and will decide not to purchase the journal, but I can’t imagine that this represents a very large group).  Last year, Hesperia published 17 articles and if $150 is the average cost of a run of offprints, then they spent about $2550 on offprints.

If every contributor over a year just said, politely, no thank you to offprints from Hesperia, we could, in effect, give the American School Publication Office a gift of $2500. I suspect that each of us would have to turn down all of our offprints because printing enjoys really significant economies of scale, and it seems fair to assume that these economies are realized at 50 copies of each article. I know some contributors will still want to “kick it olde skool” and will want to have their shinny Hesperia offprints, but I also suspect that, if given the option explicitly, a percentage of hipper, new skool contributors would turn ours down.  And I’d like to think that Hesperia and the American School would appreciate this little gift.

David Pettegrew’s Setting Stage for St. Paul’s Corinth Available as Podcast or Streaming Video

October 25, 2010 1 comment

For those of you who could not make it to the David Pettegrew’s 2nd Annual Cyprus Research Fund Lecture, fear not!  We have made David’s lecture available as both a downloadable podcast and as a streaming video.

Here’s the podcast.

Here’s the video.

David’s two days on campus were really exciting.  Not only did he speak to over 50 faculty,undergraduates, graduate students, and members of the community on the Thursday afternoon talk, but he also contributed to the history department’s “brown bag” lecture series on Friday.  At his Friday talk, he presented a great primer to intensive survey archaeology and discussed the ideas of “source criticism” as applied to ancient material culture.  Finally, David took a couple of hours and read Latin with some of our graduate students and undergraduates at our weekly “Latin Friday Morning” reading group.

It is always gratifying to see how much interest there is in the Ancient Mediterranean at the University of North Dakota.  So, if you enjoyed the lecture with here at UND, thanks for coming out! And if you enjoy the lecture via the streaming video or podcast, thanks for listening!  I also should thank Chad Bushy and Caleb Holthusen from UND’s Center for Instructional and Learning Technologies office for not only preparing the video and podcasts, but trouble shooting during the live webcast.

And, finally, thanks to David Pettegrew for agreeing to spend his fall break with us at the University of North Dakota. For more on his research and the Roman and Late Roman Corinthia, check out his blog Corinthian Matters.

Broad Period Artifacts and Survey Analysis: Quantifying what you don’t know

October 18, 2010 Leave a comment

By far the most vexing issues facing most survey projects is the analysis of artifacts datable only to very broad periods of time (a point I brought up in my blog post from last week).  In the work of the Pyla-Koustopetria Archaeological Project, these artifacts are the equivalent to objects of “unknown date” from other survey projects.  The chronotype identification system required our ceramicist to date each artifact even if these dates are exceedingly broad.  As a result, we have significant quantities of artifacts dated to periods that exceed 1000 years in length. These broad periods tend to represent two types of artifacts. 

  1. Artifacts that do not fit into any known typology such as body sherds without particularly characteristic marks, fabrics, or shapes.
  2. Artifact types that remained in use for long periods of time.  This is most often the case with various kinds of coarse and medium coarse utilities wares probably produced from local fabrics.

In some cases, the fabrics or shapes can tell use enough to allow us to group the artifact into a relatively well-defined, yet still exceedingly broad, date range.  For example, the most common period for an artifact dated to a broad period is “Ancient Historic”.  This is a date range that extends across the entire period of historical antiquity on the island of Cyprus: 750 BC – AD 750.  Almost all of these sherds (89%) are body sherds. The artifacts datable to this period appear over 77% of the total area of our survey and in 84% of the units where artifacts occur.  Statistically, the distribution of “Ancient Historic” artifacts correlates more closely to the overall artifact densities across the entire study area than any other period, broad or narrow (the correlation is .674).  This is particularly significant because artifact counts and the number of artifacts assigned to a particular period are independent variables: our artifact counts are based on the total number of artifacts visible on the ground according to clicker counts and the number artifacts dated to a particular period is a subset of the number of artifacts sampled from the units.  Finally, the fabric types present in Ancient-Historic period more or less parallel the fabric groups present in narrower, better-known, or at least more clearly defined periods (e.g. Classical or Classical-Hellenistic). For the Koutsopetria plain, for example, “Ancient Historic” material appears as coarse ware, medium coarse ware, and kitchen/cooking ware which finds rough parallels with the groups of material present from other periods and the general functional character of the area (for those of you keeping track at home, we call the Koutsopetria plain Zone 1)

Ancient_Historic_Material

Other broad periods from our site represent small quantities of obscure material that stands outside traditional typologies.  For example, there are only two sherds assigned to two chronotypes dated to the Ceramic Age (a Red Micaceous Pithos and coarse ware). Only four sherds assigned to four chronotypes received the generic Ancient date (Ancient Lekane, fineware, kitchen ware, medium coarse ware). Only one chronotype, amphoras, receive the designation Post-Prehistoric.

In old days of survey, sherds dated to broad periods tended to be neglected either at the analysis phase, or more commonly at the sampling and collection phase.  The vast majority of broad period sherds are body sherds (85%) and most of these would not appear to be diagnostic. As a result many traditional collection strategies that privileged diagnostic sherds (feature sherds with distinct marks, rims, handles, bases) would have overlooked broad period material. More recent work has at least assigned the designation of “unknown date” to these broad period artifacts, but rarely do they appear documented in the survey publication.

This material is difficult to correlate with past human activities. At best, it reinforces the notion that certain types of productive practices may have endured for long periods of time without much in the way of visible changing.  It suggests that certain vessel shapes, fabrics, and pottery categories may have continued to serve basic functions within the community, the household, and the economy for long periods of time as well. In Braudelian terms, the apparently long, slow, and relatively unchanging character of such a large part of our ceramic assemblage represents the slow swells of the sea.  The more closely dated and rapidly changing character of fine wares or even the more diagnostic parts of the vessel , for example, which tend to allow us to produce our narrow period assemblages, show the more fickle and rapidly changing nature of ancient ceramic habits.

The value then of our effort to understand the distribution and character of artifacts datable to broad periods from PKAP is that they give us a real measure of how much we do not know about material from our survey area.  And at the same time, reveal that much of the most basic practices typical of the ancient world likewise continues to elude our grasp.

Stones that Speak and some other data from the Pyla-Koutsopetria Archaeological Project

October 12, 2010 1 comment

Over the last few weeks I’ve been running what will hopefully be the final set of unique queries on the data from the Pyla-Koutsopetria Archaeological Project’s survey of the site of Pyla-Koutsopetria and its environs.  These queries are mostly following little hunches or the comments that my co-director David Pettegrew made in the margins.  It is re-assuring in some ways to find that I have not overlooked much (and I hope to circulate a working paper of my distributional analysis by the end of this calendar year), and its always fun to find little patterns.  So here are two small PKAP patterns.

For some reason on the edges of comprehension our ceramicist, Scott Moore, documented unworked stones collected in the bags of ceramics collected by our field teams.  Unworked stones collected from the fields are not traditionally regarded as archaeological material (except that their presence in a bag of ceramics has associated them with the archaeological method).  But Scott’s unworked stones do show a pattern. In the last few years, archaeologists have suggested that “background disturbance” or the presence of stones or other materials that look like ceramic objects has a clear correlation with our ability to recover artifacts from the field (the best discussion of this is in Knapp and Given, Sydney Cyprus Survey Project volume).  Presumably our field walker’s tendency to collect stones from the field might reflect a similar pattern. The map below shows the distribution of unworked stones.

Unworked_Stone

And as you can see, a pattern does emerge. Most of our unworked stone comes from units with high or modern background disturbance and this suggests two things.  First, it confirms that the unworked stones are most likely unworked (in some cases Scott documented unworked stone because he was not entirely sure that they were unworked and wanted Nick Kardulias our lithics expert to check them out).  Next, it suggests that background disturbance does influence our field walkers ability to recognize artifacts. It is encouraging to note, albeit in a tentative way, that our field walkers collected objects that they thought might be ceramics and this might give us enough confidence to at least suggest that they did not overlook objects that might be stones.

The second little analysis I ran was on the distribution of faunal remains across the site.  David Reese examined the faunal remains from our excavations in 2008 and 2009 and at the same time looked over a small quantity of faunal remains collected from the survey.  I’ve added to the map the major roads in the area (rather inelegantly displayed unfortunately).  Most of the faunal remains are near the major roads suggesting that at least some of them – particularly the chicken bones – were discarded by passing traffic.  The remains of sheep or goat bones appear cluster in the lowest lying area of the Pyla-Koutsopetria plain.  This area is pretty marshy despite efforts to keep it drained and as a result not generally under cultivation.  This kind of marginal land seems likely to have served as pasture for local flocks.

Faunal_Remans

The final analysis run over the last few days was on some very broad chronological periods into which we grouped material from the survey.  Among the broadest is the “Ancient Historic” period which stretches from around 750 BC to the end of antiquity in AD 749. The transparent dots on the map below show the distribution of artifacts datable only to this long period in the past. Their distribution more or less follows over all artifact densities (with the exception of Kokkinokremos where the ceramicist who read our Iron Age to Bronze Age material used a slightly different designation).  This suggests that artifacts grouped into this broad period are not likely to represent a single class of difficult to identify material, but rather a whole group of artifacts from multiple periods that remains outside of traditional ceramic typologies and chronologies. It is never heartening to see how much material from a survey goes unidentified (or identified in only the broadest possible way), but it is encouraging to see that it does not cluster in suggestive ways.

Ancient_Historic_Sherds

2010 Cyprus Research Fund Lecture: Setting the Stage for St. Paul’s Corinth

September 29, 2010 Leave a comment

This year’s Cyprus Research Fund Lecture will feature Prof. David K. Pettegrew of Messiah College.  David is not only a long time collaborator with my in both Greece and Cyprus, but also regarded as one of the foremost scholars on Late Roman Corinth.  His talk will focus on over a decade of archaeological and historical research on the Isthmus of Corinth.  We hope he’ll let us podcast his talk so that anyone, anywhere can listen to him!

Here’s a description of his talk:

Corinth has come down in history as the quintessential maritime city that became powerful and wealthy by capitalizing on the movement of commercial goods and peoples across a narrow isthmus at the center of Greece.  The connecting isthmus also allegedly made Corinth politically unstable, corrupt in morals, and exceptionally depraved.  As St. Paul’s letters show, Corinth was a Christian community with problems.

Why was Corinth so consistently associated with travel, trade, and wealth in ancient thought?  And how did a land bridge facilitate commerce and traffic and contribute to the city’s development in the Roman era?

In this lecture, David Pettegrew considers what the ancient texts and material evidence suggest about travel and commerce across the Isthmus and its effects on the maritime character of the city in the first and second centuries AD.

The talk is Thursday, October 21st in the East Asia Room of the Chester Fritz Library.  There’ll be a small reception after the talk.

Pettegrew.jpg

Categories: Archaeology, Conferences

Ambivalent Landscapes of the 6th century at Corinth in Contrast

September 28, 2010 Leave a comment

As readers of this blog know (here and here), I’ve been working on a conference paper for the Corinth in Contrast Conference at the end of this week.  This paper is, in effect, an archaeological and architectural argument for the impact of Justinian on the Corinthian Isthmus.  (These ideas developed, more or less, from my analysis of a pair of texts that reference Justinian from the Isthmus).

You’ve read the drafts, so here’s the paper:

Caraher Ambivalent Landscape 2010
http://d1.scribdassets.com/ScribdViewer.swf?document_id=38304843&access_key=key-29s5z4gyidaj9o4ldpu0&page=1&viewMode=list

Digital Workflow and Microhistory

September 27, 2010 2 comments

As you might imagine, I am pretty excited that Steven Ellis’s team’s use of the iPad as their primary,field data recording device is getting some attention lately.  I imagined this kind of digital workflow when I began working with Scott Moore to design the digital recording components of our project in Cyprus.  Scott and I, from what I recall, always assumed a paper stage.  This is what that stage looks like now:

PKAPPaperStage

I think that we fell back on the old archaeological wisdom that a paper stage somehow serves as a more dependable back up that digital copies. This led us to copying the entire archive each year and carrying it home (and still managing sometimes to lose copies of the original or not have them where we needed them). With a fully digital workflow, it is, of course, much easier to make copies of every stage of the documentation process and store them multiple places, and, provided that a good version control system is in place, manage these copies.

I know that I also subscribed to the idea that paper copies preserve more fully the archaeological thought process.  We insisted that our trench supervisors not keep separate, personal, notebooks (they did anyway) and write directly onto our recording sheets as they excavate.  The hope was that the image of the stratigraphic unit form provided the best record of the process of excavation. In fact, as much as was possible, we have sought to associate digital images of these sheets (and the trench plans of each stratigraphic unit) with the digital copies of this data.  This remains a time consuming process of keying the data from each sheet and digitizing each days trench plans. Having supervised the keying of most of our field data, I can attest to the hours of time and concentration that went into producing our digital versions.  It’s mostly done now, but it was a onerous process and we haven’t quite produced data with the kind of immediate transparency that we had hoped for (although it is all still possible).  Using the iPad to record directly into digital form the basic data from the trench would pay immediate dividends by streamlining the data collection process.

On the other hand, I do wonder whether some of the data associated with the archaeological process might be lost. I was thinking about the faint evidence for revision that appears on our paper recording sheets – typically under various forms of erasure (usually a strikethrough) – that preserves irregular fragments of the archaeological through processes.  If Wikipedia has taught us anything, digital recording makes it possible to record this same data by recording each change to the data set and each earlier version.  In effect, the digital data collection could preserve a kind of digital palimpsest of each key stroke, deletion, adjustment, mistaken measurement.

I am fascinated by this kind of micro-history and its potential to reveal patterns of behavior across an entire project and capture a more intimate look at how the archaeological method is performed.

Just for fun, I used The Archivist to capture some of the buzz about the Apple story on Ellis’s use of the iPad. The Archivist lets you download all the Tweets associated with any search criteria.  For my little experiment, I captured all the Tweets that used the word “Pompeii” and “iPad”.  As of 6 am this morning when I staggered into my office, I captured 520+ Tweets.  I then plotted them by hour over the last few days.  Here’s the chart.

image

They have averaged about 5 tweets an hour over the last 100 hours or so.  The peek was 95 tweets per hour between 12:20 pm and 12:20 pm on September 23rd.  Thus surge continued over the next hour where they had over 80 tweets and subsided to under 40 tweets later by 3:30 or so. The great thing about The Archivist is that it lets you download your Tweets so that you can data mine them using an application like RapidMiner.  I didn’t do that, but I did do some simple mining.  For example, Ellis’s name is mentioned in 131 of the tweets (or about 25% of the time) and about 16% of the Tweets are obvious “RT-style” re-tweets. In Tweets with both Pompeii and iPad in them Ellis’s university, University of Cincinnati, was never once mentioned nor was his project’s name, the Porta Stabia project (even in two Tweets that appear to come from “official” University of Cincinnati channels!).  In the hyper economical world of Twitter, there are good reasons not to include long word like Cincinnati or relatively obscure project names.  In contrast, the most common phrases is “Discovering ancient Pompeii with iPad” which was the title of the Apple article and it appeared in 62% of the Tweets (suggesting the far larger number of retweets happen than had the traditional “RT” designation).  For the record, my Tweet, which occurred very early in the Tweet cycle led to only three retweets. 

This is the kind of micro-historical analysis that could be possible by mining the minutia preserved in a fully digital workflow.

By the way, it’s a double blog day! I thought that I needed to do something to mark my 800th post and in the tradition of the National Register of Historic Places, I thought I’d just put up a marker (with a few links, it is a blog after all).

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

September 23, 2010 Leave a comment

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.

Plotting Cut Blocks Across Pyla-Koutsopetria

September 21, 2010 Leave a comment

Between 2005 and 2006, the Pyla-Koutsopetria Archaeological Project documented over 500 features from the Koutsopetria plain.  Most of these features were cut blocks of various sizes, material and descriptions as well as a handful of features associated with ancient agricultural installations (bit of an olive press, some andesite mill fragments, et c.).  Over the past couple of days, I finally got to analyzing this data beyond simply observing that we have lots of cut blocks.  The field team in 2005 and 2006 recorded detailed information regarding the location, size, and in many cases generally descriptions of each block and keyed them into a database that we could integrate with our GIS.

Most of the architectural fragments including cut limestone and gypsum blocks, are concentrated in the immediate Koutsopetria plain where farmers have moved them to stone piles on the edges of the fields. Check out our newest additions (partially edited) to our Omeka Collection: Pyla-Koutsopetria from the Air to get an idea of what these stone piles look like.

http://mediterraneanworld.und.edu/archive/fullsize/koutsopetria_north_2007_4944fb9f0e.jpg

http://mediterraneanworld.und.edu/archive/fullsize/koutsopetriawest9_2010_7156214481.jpg 

The most common type of cut block is made of local limestone and probably quarried on site. The majority of the blocks fall between 0.3 and 0.7 m in length and 0.3 and 0.5 in width. For the blocks where all three dimensions are visible, their volume falls between 0.06 and 0.03 cubic meters. This produced blocks of between 75 kg and 140 kg which would be relatively easily moved for construction. Some blocks, of course, could be much larger exceeding 1 m in length and weighing close to 500 kg. With blocks of this size, there is almost no doubt that some large scale, monumental architecture once stood in the immediate area.  Here’s a distribution map.  The grey grid in the background is our survey grid and the color of the dots relates to the volume of the stone.

CutBlocks

We also documented a significant quantity of cut gypsum block.  Since marble did not naturally occur on the island, Cypriots often used gypsum as a substitute in more elaborate buildings.  These blocks are generally similar in size to the cut limestone blocks with lengths of around a half a meter and widths of 0.3 meters. The average volume of blocks was similar to that of the cut blocks with only a few blocks exceeding 0.1 cubic meters. There were slightly more smaller blocks owing most likely to the more friable character of gypsum. Most blocks fell between 0.01 and 0.06 cubic meters. Gypsum has a lower density than limestone and the blocks had correspondingly lower weight usually between 25 kg and 140 kg. Many, much smaller fragments of gypsum were scattered across the fields and several very large blocks appeared clustered together. Here’s a map:

GypsumBlocks 

Finally, we also discovered a small quantity of marble from across the site.  Most of these came from the central area of the Koutsopetria plain embedded in rock piles at the edges of cultivated tracks of land. The marble fragments are small < .30 m in maximum length and relatively thin <.04 m suggesting that all but one marble fragment was revetment or floor slabs. The wide distribution of material perhaps indicates that there were several marble clad buildings on the plain of Koutsopetria even though so little marble survives.  Here’s a map:

MarbleBlocks

The next step in analyzing this material is considering its relationship to the re-used blocks found in the excavations at Koutsopetria and the construction techniques used in the fortification wall surrounding Vigla.  It certainly seems possible that the majority of cut stone blocks scattered around the Koutsopetria plain came from the easily quarried fortifications at Vigla and perhaps also the extensive walls surrounding the Bronze Age site of Kokkinokremos.  Gypsum blocks had fairly limited uses architecturally owing to their lack of strength and value as prestige materials.  The gypsum fragments from around the site probably served in specific places in buildings and comparing their sizes to in situ blocks from elsewhere on the island might give us some idea of how they were used.

 

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