The ditch and the dogs

This past week, a handful of special guests helped to excavate Unit 12 — the last unit of the project! Their efforts yielded the clearest profile views of the earthwork ditch that we’ve seen yet.

North wall of Unit 12, with the ditch profile. For scale, the top of the ditch below the plowzone is about 180 cm wide (the unit as a whole is 230 cm wide). The right side is the outer edge of the ditch (i.e., outside the enclosure).

Of course, we’ve cross sectioned the ditch before, in last summer’s Units 6 and 8. In both cases, the profiles revealed a complex history of ditch digging and infilling, including multiple zones of fill, subsequent post emplacement, and post removal. However, sampling these profiles for further analysis was more problematic than anticipated. One profile was dominated by a rock-filled posthole, so it was difficult to clearly see its stratigraphy. Another provided bulk soil samples for flotation (thanks Stephen Carmody!), after which there wasn’t much left for taking micromorphology samples. Last, in Unit 8, we allowed the profiles to dry out too much before sampling, which led to some pretty messy micromorph blocks.

Rachel and Beau, peeling back the upper zone of ditch fill.

So! With the help of volunteers Rachel Applefield and Beau Carroll, a new unit was tackled, with the explicit goal of generating some sampling-friendly profiles. Luck was on our side — neither wall of the unit included a rock-filled posthole, and though the recent rains have led to some muddy work, the layers of fill are proving much easier to sample than those that got so baked out in August.

Sarah, shoveling back a balk of sterile subsoil to get a better look at the edge of the ditch -- as her noble dog Ty looks on.

On Saturday, geoarchaeologist, friend, and all around awesome lady Sarah Sherwood came by Garden Creek with her pack of canine companions. She lent her expertise to our sampling efforts and helped to revise some working interpretations. For instance, contrary to some of my preliminary (and admittedly inexpert) notions, Sarah has hypothesized that the bottom zone of ditch fill may have been filled in deliberately (instead of through erosion). If she’s right, this suggests purposeful, historical changes in the way the enclosure was used, and perhaps shifts in the meaning of this space through time.

Though parts of the profiles are pretty chewed up, thanks to the resident earthworms, Sarah and I are hopeful that micromorphological analyses of these deposits will shed even more light on the history of this unique feature. I doubt her dogs share our interest in this work, but it was a pleasure having them — along with all these great archaeologists — at the site!

Sarah's dog Leo, surely contemplating the ditch.

 

 

Posted in Excavation, Features, Micromorphology | Tagged , , , | 3 Comments

Live from Ingles

After four days of unseasonably awesome weather, it’s raining in Canton. But, if you’re going to wait out some thunder showers, you may as well do it at the local grocery store while updating the blog.

West profile of refuse pit inside the enclosure.

Last week, Scott Ashcraft and I finished excavating a large refuse pit inside the ditch enclosure. The pit consists of two main zones of fill (and an rodent burrow). The lower zone reminds me of the lowest fills of the earthwork ditch: subtle lenses of light yellow and dark gray clay loam, with few artifacts. I think this might indicate that the original pit may have filled in slowly, through erosion, over time. The upper zone, in contrast, is dark and homogeneous, with heavy charcoal flecking and numerous Connestee (late Middle Woodland) ceramic sherds.

This pit, about two meters from the interior edge of the ditch, is surrounded by numerous postholes. In a small, 2×3 m unit, we’ve excavated more than 25 of these round stains, which vary in diameter from 10-20 cm, and in depth from 15-50 cm below the plowzone. I’ve recorded the locations, dimensions, and fill characteristics of these posts in the hope that I might tease out which ones go with the same building, rack, screen, or other structure — we’ll see! What’s clear at this point, at least, is that the enclosed area demarcated by the ditch was intensively reused, possibly by groups regularly coming together at the site for visits and ceremonies.

The rain appears to be stopping (famous last words), so back to the site it is! Please keep your fingers crossed for dry weather for the last few days of fieldwork!

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A Visit from the Arthur Morgan School (aka a great day at Garden Creek)

From now on, when I chat with an archaeologist who’s feeling tired and slow midway through a field season, I will have one recommendation: invite students from the Arthur Morgan School in Burnsville, NC to your site for an afternoon. Today, several students, their instructors, and USFS archaeologist Scott Ashcraft dropped by Garden Creek, where they received a tour of the site and provided tremendous help busting plowzone over Unit 12. This 2×1 will be the last unit we excavate as part of GCAP, and it will yield some more earthwork ditch profiles from which I can get better micromorphology samples. Thanks to the enthusiasm and excavation/screening talents of the AMS team, we are a lot further along this week than I expected — and that’s a great place to be with less than two weeks in the field to go! Thanks so much to this young crew for the shot in the arm on “distractingly beautiful” March day!

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Special Guests at Garden Creek

The UNC crew huddling around Tim's computer in the snow, checking out the latest geophysical survey results.

Despite the wind and snow, we got quite a bit of work done at Garden Creek this week, thanks in large part to the return of UM graduate student Ashley Schubert and the assistance of several more graduate students from the University of North Carolina’s Research Laboratories of Archaeology. With their help, we were able to remove the sod and plowzone over two new units near Mound No. 2.

David and Erin working in Unit 10.

David Cranford and Erin Nelson tackled the first unit, which targeted a circular anomaly that yielded a considerable amount of charcoal in a small core. The feature was immediately visible under a relatively shallow plowzone, and subsequent excavation yielded several Middle Woodland sherds and soil samples that will be floated to recover botanical remains.

Top of pit feature in Unit 10, at the base of the plowzone.

The excavated pit in Unit 10, south profile.

In the backyard, Meg Kassabaum and Anna Semon opened up a 4×1 m trench over two anomalies. A number of ceramic sherds and chert and crystal quartz flakes were recovered from the plowzone. Ashley and I finished cleaning off this unit today, and will begin excavating its features soon.

Meg and Anna working in Unit 11. By this time, it had thankfully stopped snowing and the sun had come out.

Unit 11 at the base of plowzone. The eastern feature is visible near the bottom of the photo; the western feature is in the shadow of the wall at the top.

While all this was going on, Tim continued to expand the magnetometer and magnetic susceptibility surveys. He also completed ground penetrating radar survey across nearly 0.9 hectares, over and around the earthwork enclosures. On Wednesday, he was able to show some of the results to visiting archaeologists from the National Forests of North Carolina, who contributed much appreciated interpretive insights about our ongoing fieldwork.

Friends from the Forest Service along the Pigeon River, where they (with the help of local landowner Tom Anspach) recently identified some rock art associated with the prehistoric occupations of Garden Creek.

Tim will be here for two more days, so the geophysical investigations at Garden Creek are coming to a close. Luckily, the data he’s generated has located a number of interesting features that will be the focus of activity for the next few weeks.

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First Week Back – GCAP 2012

Thanks to a stretch of terrific late winter weather, we were able to accomplish quite a bit in our first week back at Garden Creek. This final phase of fieldwork includes both geophysical survey and excavation, in order to cover as much of the site as possible and to  study in greater detail certain areas with rich archaeological deposits.

Dr. Tim Horsley conducting ground penetrating radar survey at Garden Creek.

Last year, Tim Horsley surveyed a large portion of Garden Creek using a magnetometer, which pinpointed the location of several anomalies, including pits, hearths, and the earthwork ditch enclosures. Now, he’s back at the site to expand the magnetometer survey grid and to try out several additional geophysical techniques. So far, he’s used ground penetrating radar to produce a high resolution, three-dimensional map of the buried earthworks and surrounding areas, and magnetic susceptibility to identify general trends in the intensity of occupation across much of the neighborhood.

Magnetic susceptibility survey east of the earthwork enclosure.

Meanwhile, with the help of University of Michigan graduate student Travis Williams and undergraduate Sophia Reini, we’ve opened up a 2×3 meter unit (Unit 9) near the earthwork that we excavated last summer. This unit was positioned to target an anomaly inside the enclosure, so that we could learn more about the activities that were going on there. Once we cleared off the plowzone, we identified an arc of postholes that appear to demarcate the edge of the anomaly; it may be that the anomaly is a more deeply buried hearth or other feature inside of a structure. In addition, we identified a couple of pits in this unit, including one that was full of (though not apparently lined with) fragments of sheet mica. As with the mica we recovered from the ditch last summer, several of the fragments appear to have deliberately cut edges.

Travis and Sophia scraping off the last of the plowzone in Unit 9.

Assuming the weather holds, we plan to excavate the remainder of the features in this unit over the next few days. With luck, the information we learn from them will tell us something about Middle Woodland ceremonialism in and around Garden Creek’s earthen monuments. Time and further excavation will tell…

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Upcoming Fieldwork at Garden Creek

In the last year, members of the Garden Creek Archaeological Project spent nearly four months in Plott Farm neighborhood in Canton, conducting geophysical survey, placing test units and shovel tests, and excavating intact features dating to the Middle Woodland period. Now, thanks to the generosity and patience of local residents, we are coming back for just a little bit more.

The Pigeon River from the lower terrace at Garden Creek, February 2011. We are hoping for similarly blue skies and pleasant temperatures in Feburary and March 2012!

From February 26 till the end of March, I plan to be at Garden Creek with new and familiar faces to answer some questions that have arisen in the course of ongoing analysis. For the first few weeks, Tim Horsley will be joining me with his magnetometer and other geophysical instruments; we aim to map portions of the site we weren’t able to get to last year and to re-map certain archaeological “hot spots” using different techniques for higher resolution. After that, a crew from the University of Michigan (and any other friends I can convince) will help to open up a few more units around the earthwork ditch. In particular, we want to target anomalies inside the enclosure and increase the sample of surrounding features for comparison to materials associated with the mound.

This post is all to say: if you see us out and about it Plott Farm next month, please feel free to stop by and say hello. We’re happy to tell you what we’re doing and happy to answer any questions you might have. In the meantime, please just keep your fingers crossed that the weather will stay fine and the temperatures warm for our early spring expedition!

As always, visitors are welcome at GCAP. Stop on by!

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Dealing with Debitage (by Erika Loveland)

Over the last couple of months, I have been working on measuring and recording attributes of the Garden Creek’s off-mound assemblage of lithic debitage — small pieces of chipped stone that result from flint knapping. Analyzing this material can help answer several important research questions:

  • What sort of raw material was used for stone tool production?
  • Is the material locally available or did it have to be procured outside the Garden Creek vicinity? If so, where did it come from?
  • What can the lithic assemblage tell us about the sorts of activities that were occurring at Garden Creek: for instance, flint knapping, stone tool exchange, meat butchering, or producing some other craft using lithic tools (e.g. cut mica)?

Typical lithic assemblage from a 1x1m excavation square. Mostly chert with some crystal quartz raw material, and, with the exception of the tool fragment at the upper left, all flakes with no macroscopic use wear. Thanks to Ashley Schubert for the photo.

So far, the main raw materials identified in the debitage assemblage are several varieties of chert or flint and perfectly clear crystal quartz. There is no major chert outcrop in Garden Creek’s immediate surroundings, so we need to think about the sorts of procurement and transportation strategies that could have gotten them to the site. The crystal quartz may be more locally available, but based on our discussions with local archaeologists, it is occurring at a higher frequency at Garden Creek than at other sites in the region — another pattern that demands explanation.

Additionally, the very small size of most of the pieces of debitage from Garden Creek indicate that, at least in the areas we excavated, tools were undergoing in a later stage of production. In other words, these tiny flakes were probably produced in the late stages of shaping knives, scrapers, and projectile points or in the course of re-sharpening them.

At this rate, I will finish analyzing the debitage recovered during the 2011 season this semester. Then I can look at how the patterns described above (or others) map out in different areas of the site, and determine if certain areas were being used for certain activities. I  hope to be able to present some of my results at the Southeastern Archaeological Conference next fall.

Erika, zeroing in on a flake for analysis.

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Making maps

Thoroughly settled into the chilly winter term, I am starting to digitize some of the excavation maps we drew in the field. Of course, we took hundreds and hundreds of photos to document what we were digging, but as we begin interpreting some of these deposits, our schematic maps are proving very helpful in clarifying patterns that are difficult to make out in photos.

A months-old shot of Sophia and Jess (my crack team of mappers) creating a plan or "bird's eye" view map of the postholes that appeared during our excavations around the earthwork ditch.

Case in point: in the south wall of Unit 8 (the 5×3 m block we opened over the earthwork), we exposed a only a small portion of the ditch in cross section. Given the orientation of the entire feature — essentially coming out of the southwest corner of the unit — this clipped, outer edge was tricky to photograph. In person, you could clearly see distinct strata of ditch fill, but the lack of light in the corner of the unit made it hard to capture on camera.

The problematic south wall is at the top left. In the west profile (right) you can still see some of the intact fill layers.

So, field crew member Alicia Michalski and I made a schematic profile map, documenting the boundaries between major fill zones and other stratigraphic information we observed. To do this, we set up a level line above the edge of the wall, from which we measured the depth of various points along these boundary lines. Back in the lab, I scanned our original pencil-on-graph-paper map, traced the image digitally, and produced this map:

Although this map is not quite finished (among other things, I’ll eventually include more thorough descriptions of the zones of ditch fill), it still conveys some things that were tricky to see, both during excavations and in the photograph. For one thing, the east edge of the ditch (the boundary between Zone C-2 and sterile subsoil) is much steeper in reality that was suggested by our final excavation cuts. The eastern edge was a major challenge to isolate as we were digging for two main reasons. First, it was throughly obscured by earth worm burrows and the worms themselves. Second, the subsoil was very similar in color to Zone C-2 — a point which merits further consideration.

As you can see in the digitized map, the bottom-most layer of ditch fill is divided into Zone C-1 and Zone C-2. During horizontal excavation, it appeared as mottled sediment — dark, organic loam in some areas, and stickier, yellow clay in others. As I mentioned above, the clay was nearly the same color as the subsoil, but it was very different in texture. Instead of the extremely dense, sterile clay, which troweled away in ribbons, Zone C-2 was quite soft and cake-y. The “sterile-ish-ness” of Zone C-2 caused me and Jess no end of confusion during our horizontal excavations, but luckily, the vertical profile view offers some clarification.

The top of Zone C, with the bases of some of the rock filled postholes still in place. Notice the mottling of the yellow and dark brown sediments in the ditch, but please don't pay much attention to the patches of light soil just outside the ditch. It was late afternoon, the dirt had baked out and lightened in the sun, and our water sprayer was empty. Mea culpa.

The relatively steep angles of the Zone C deposits suggest that this sediment slumped into the ditch, probably as a result of erosion. Zone C-2 is likely run-off from the steep walls of the original ditch walls, while Zone C-2 may be top soil that washed into the ditch. The alternating layers of Zone C-1 and Zone C-2 suggest that after the ditch was completed, it was left open long enough for several erosional episodes to occur. If the stability of the walls of our excavation units are any indication, it would take a some pretty serious rainstorms or quite a long time for that much erosion to happen; Garden Creek’s clayey soils are tough! In contrast, Zones A and B, both of which had higher artifact densities that Zone C, were very homogenous, and may have been deposited very quickly. It will be interesting to see if future micromorphological analyses support or refute these hypotheses. Of course, what this all means with regard to on-site activities remains to be seen… but that’s for a later (and hopefully more concise!) blog post.

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Sherd ID

Sophia reftting sherds from a potbreak that was recovered from the top zone of fill in the earthwork ditch.

As the end of the semester rapidly approaches, ceramic analysis continues in the Eastern North America range at UMMA. Most of the sherds we have looked at so far appear to fall neatly within Appalachian Summit pottery types like Pigeon, Connestee, and Pisgah, but we have a had a few surprises. For example, the sherds in the photo below have a surface treatment that we don’t recognize: extremely fine cordmarking interspersed with plain bands. These sherds are sand tempered, though two have a couple granule-sized white quartz inclusions. They were recovered from a midden that included Woodland (Pigeon and Connestee) and Mississippian (Pisgah) ceramics.

Tiny mystery sherds

Please let us know in the comments or via email (apwright@umich.edu) if you recognize this type of pottery. We’d also appreciate suggestions of regions or periods that might merit further literature review, in order to reveal their time/place of origin (if they’re non-local). It may be that these humble artifacts could tell us something really interesting about the sorts of interactions that were taking place at Garden Creek in the past.

Posted in Ceramics, Features, Students | 2 Comments

Mica in the Museum

What do you get when you combine the monotony of artifact washing with visits to friends’ excavations and trips to archaeological conferences? Unfortunately, a long hiatus in posting at the Garden Creek Archaeological Project Blog!

Now entering the North American Archaeology range...

But don’t let the radio silence fool you. We are hard at work in the North American Archaeology range at the UM Museum of Anthropology, collecting data from the artifacts we excavated this summer. Soon, Sophia and Claire will be posting about the sorts of ceramic attributes they are looking at in the course of analyzing potsherds, and Erika will explain why she’s recording information about the hundreds of pieces of chipped stone debitage we found at the site.

Erika weighing a small chert flake. She is quickly filling the notebook on the right with observations!

In the meantime, though, we post to poll the audience: does anyone have any suggestions for how to clean fragile sheet mica artifacts? We managed to bring quite a bit of this material back from the field, but some of it is encrusted with dirt that we’d like to get rid of. This would allow us to better see signs of purposeful cutting under a microscope. Thanks in advance for your input, and for your patience as we get back into the swing of blog posting!

A piece of mica from the earthwork ditch, with a plausible cut edge at the top.

The same piece of mica (above) in situ. We managed to just avoid it when we took removed the flot column.

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