Day 13 saw us continue down the path toward wrapping up our excavations for the semester. The "upstairs" is going along willingly, the "downstairs" . . . not so much.
As I wrote last week, we wrapped up level excavations in Unit 4 and 6 and had just a few loose ends (final scraping and mapping of floor, etc.) in Unit 5. Today's goals were to finish the level excavations in Unit 5 and document the walls of the block by photographing and making profile drawings. I took my own notes on the sediments in the profiles and collected a charcoal sample from one of the probable features exposed in the floor of Unit 4. The block was crowded.
As I wrote last week, we wrapped up level excavations in Unit 4 and 6 and had just a few loose ends (final scraping and mapping of floor, etc.) in Unit 5. Today's goals were to finish the level excavations in Unit 5 and document the walls of the block by photographing and making profile drawings. I took my own notes on the sediments in the profiles and collected a charcoal sample from one of the probable features exposed in the floor of Unit 4. The block was crowded.
All ten students working in the block at the same time. Prior to profiling the walls, we covered with floors with landscape fabric and a thin layer of backdirt to protect the intact deposits exposed in the floor from trampling.
Profile drawings are key to understanding the deposits from which we removed artifacts. It is often easier to understand the stratigraphy in profile (i.e., in a vertical plane) than in plan (as you're excavating through it). This is very true at this site, where the loose sand dries out quickly and makes it more difficult to move in the unit without disturbing artifacts and obscuring variation in the exposed sediments.
Drawing a profile uses many of the same skills the students learned while piece-plotting artifacts and making horizontal maps. The big difference is that one of the dimensions is elevation. The traditional way of drawing a profile is to establish a level line along the plane that you're drawing, measuring in everything in relation to that line. Setting a level line is simply a matter of stretching a string tightly between two anchoring points (typically gutter spikes or chaining pins), using a simple mason's line level to make the string level.
Drawing a profile uses many of the same skills the students learned while piece-plotting artifacts and making horizontal maps. The big difference is that one of the dimensions is elevation. The traditional way of drawing a profile is to establish a level line along the plane that you're drawing, measuring in everything in relation to that line. Setting a level line is simply a matter of stretching a string tightly between two anchoring points (typically gutter spikes or chaining pins), using a simple mason's line level to make the string level.
An example of a profile wall prepared for drawing. The red item over the north arrow is a line level.
By the end of the day, the students had completed all the work in the "upstairs" block and had gotten much of the backfilling done. To protect the floors and walls until I can open the excavation again, we lined everything with landscape fabric and placed pieces of chipboard along the walls. The landscape fabric provides a marker between what's been excavated and what hasn't and, unlike plastic, allows water to pass through. The purpose of the vertical wood panels is to allow us to shovel right up to the walls when the fill is removed in the future. The whole enterprise will be filled and buried.
Excavation block with Units 4 and 6 prepped for backfilling.
While everything went smoothly in the "upstairs," the "downstairs" portion of the site continued to fight back. DuVal and I visited the site mid-week to deliver a load of lumber for building the buttressing that will protect the profile wall until I can return to it again. I took that opportunity to try to salvage a decent photo of the deposits exposed in the wall after the collapse -- DuVal and I scraped it as best we could and waited for the sun to move to provide natural shade (early afternoon). It's not a perfect picture, but it wasn't a perfect situation.
Photograph of profile exposed by the Unit 9 wall collapse. Five main zones are clearly visible. The slightly darker zone that I presume dates to the Middle/Late Archaic doesn't show up well in this photo; it's in the upper potion of the bottom, lamellae-filled zone.
On Friday, Jim Legg completed his profile drawing of the intact north wall of Unit 9 and drew the profile exposed by the wall collapse. You can't really tell from the photo, but the surface is fairly irregular. In order to make it possible to build a wooden structure to protect the profile from further damage, I had some students cut back some portions of the lower zones to produce a surface closer to a vertical plane. We screened the sediment. I was hoping that perhaps we'd finally get a diagnostic artifact from those lower zones. But, alas, no.
Big doings "downstairs:" Duval builds, students excavate, and Jim ponders.
By the end of the day this coming Friday, the excavated portion of the "downstairs" profile wall will be protected behind wooden buttressing, one way or another. We'll line the wall with landscape fabric, install vertical wooden panels, and then fill the space between the two with sand. It would have been a lot easier to do this, of course, if the Unit 9 wall had not collapsed. The more irregular the wall, the more sand is required to fill in the spaces. More sand means more pressure on the wall, which requires more strength. The Unit 1 and 2 walls were already uneven, and the bottom part of the reconstructed buttressing there suffered a blowout during backfilling. I think we'll end up piling sand on the bottom portion of the buttressing to counter-act the pressure pushing outward. If there's one thing we have a lot of, it's sand.
Finally, I was happy to get a group photo with everyone in it. Good job, 2017 Broad River Archaeological Field School!
Finally, I was happy to get a group photo with everyone in it. Good job, 2017 Broad River Archaeological Field School!
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