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.

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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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GCAP: Indoor Version

Some freshly washed artifacts laid out to dry. These came from one of the plowzone levels; not surprisingly, they include some notable examples of Pisgah ceramics (the lower few sherds in particular).

Finally, we’re ready for round two of research for the Garden Creek Archaeological Project! After a few weeks of post-fieldwork organization, I’m back in the North American Range of the University of Michigan’s Museum of Anthropology to process and analyze the artifacts we collected this summer at the Garden Creek site. Luckily, some familiar faces will be helping out with this phase of investigation.

The gang is back together again! Erika and Claire are taking time out of their busy class schedule to wash artifacts.

In the next few weeks, field-tested students Claire, Sophia, and Erika and I should finish washing the last of the artifacts and will begin looking at some assemblages in more detail. Claire and Sophia will be focused on the ceramics, while Erika will be working on the lithics. Before too long, we hope to be able to post some ongoing interpretations based on our laboratory findings.

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Final field photos

After a whirlwind week of photography, profile mapping, micromorph sampling, and backfilling, we successfully completed the first and longest phase of fieldwork for the Garden Creek Archaeological Project. Alicia and I made the trek back to Michigan over the weekend, and soon, I will begin analyzing the artifacts from the site at the University of Michigan Museum of Anthropology with several of the students who joined us earlier this season. Throughout this process, we plan to regularly update this blog with our ongoing findings, so please check back often!

For now, we offer a few photos of our last week in the field, including the final shots of the 110 cm deep earthwork ditch that kept us busy in August. We would also be completely remiss if we didn’t take this opportunity to thank our local archaeological colleagues for their help and advice this season (in particular, Scott Ashcraft of Pisgah National Forest, who spent a week in the ditch with us) and the many residents of Plott Farm who facilitated our work this summer, especially Will and Brittany Warren, Joe, Brenda, and Jordan Worley, Tom and Susan Anspach, and Robert and Julie Cathey. The ability to work so closely with the local community made this one of my most fulfilling field experiences, and I can’t wait to continue our collaboration in the near future. Project members plan to be back in Haywood County intermittently through the next year, to give talks at the local schools, install at exhibit at the Canton Area Historical Museum, and undertake some quick and focused excavations next spring — we’ll see you all again then!

Scott and Alice clean scraping the ditch for a photo. The holes on the left are bisected stains and postholes.

Unit 8, with the ditch entirely excavated, looking grid southwest (about true west). The filled-in unit in the upper right was the crosssection tench. According the the magnetometer, the ditch turns a corner in the grassy area between the two units.The ditch, looking grid south. It just barely starts to turn a corner in the southwest portion of the unit. The ditch itself comes out of the west wall at an angle.

The ditch looking grid north. In the bright, late afternoon sun, you can really see how yellow the subsoil clay is! The dark area of the west wall (lower left) is actully ditch fill, because the ditch itself exited this wall at an angle. The dark stain in the upper left portion of this wall is an intrusive pit the probably dates to the lter Pisgah phase use of the site. In the north profile, you can see the three major zones of ditch fill, some of which include lenses of dump and erosion episodes.

Southwest corner of Unit 8. The three major (some homogeneous, some striated) zones of fill are visible in both the south and west walls here.

Inside the ditch, looking north. The dark spot in the north wall is the remains of an isolated dumping event that included quite a bit of charcoal. Note how steep the walls are and how flat the floor is!

Backfilling with John Wright and Rita Pelczar (my parents!) who drove down from Madison County to help us close down the site for the season.

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Bisecting postholes, from Alicia Michalski

[While we finish up in the field today, Alicia Michalski has provided a great post on what has been keeping her busy for the last few weeks: bisecting postholes!]

Alicia, bisecting a posthole.

While the ditch has been the main focus in the latter part of our excavations, I have been concentrating on the post holes that lay outside of the larger feature in Unit 8 (the 5×3).Th ese may look less impressive than a massive earthwork ditch, but the data we collect when we bisect postholes can reveal the answers to very important questions. Bisecting a post hole and recording the various measurements is one way to find a possible pattern among what at first looks to be a random scattering of features.

In order to bisect a post hole, I first need to clean scrape the surface area in which I am working. This reveals darker sediment, more brown in color than the yellow fill which surrounds it, indicating a possible post hole. Then I take a top elevation of the post hole, which indicates the depth at which the post hole was dug in relation to the surface. Next, I cut the post hole in half and create a mini-profile, digging down and keeping the back wall as clean and straight as possible. The difference in the color of the sediment is one of the most important factors in this process. It reveals the boundary of the post hole, if it veers off or is diffuse (indication of a rodent burrow) and where the post hole stops. This is why keeping the back wall clean and smudge-free is critical.

One of the several dozen postholes we've bisected in the last few weeks. The posthole is the dark stain in the middle, surrounded by yellow subsoil.

Once I’m sure I’m at the bottom of the post hole, I record bottom elevation and a description of how the bottom is shaped (pointed, rounded, or flat). Then I take out the remainder of the post hole from the wall I had bisected, leaving a round column from where the sediment that had filled the post hole had been. The sediment from the post hole is then screened to reveal any artifacts that may be associated with it.

Bisecting a post hole is certainly a process that takes a bit of skill and a lot of patience when the lighting isn’t cooperating. But the data that has been collected from all the posts will be invaluable when it comes to teasing out similarities and differences in post features that might relate to different architectural structures.

 

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Front page news

Today’s Haywood County Mountaineer newspaper published two great stories on the Garden Creek Archaeological Project. If you want to check them out:

Dig at Garden Creek shows renewed interest

Property owners preserve history

Thanks to Peggy Manning and the Mountaineer for the coverage!

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