We had another sunny Friday with highs in the mid-50's. I saw a bee over the weekend, so it looks like the worst of another brutal South Carolina winter is behind us.
As I wrote last week, my hope for this Friday was that we would end the day being able to say with some confidence whether Zone 2 (the dark zone beneath the plowzone) is a buried plowzone or an intact cultural deposit. Unfortunately, I still don't have definitive evidence either way. Based on the day's work, however, I'm now leaning more toward the idea that we are, in fact, dealing with an unplowed prehistoric deposit.
If Zone 2 is a buried plowzone, we'll expect to see some evidence of plowing (e.g., plow scars or plow-truncated features) at the interface between the base of the zone and the underlying sediments. We're not to that interface in any of the block units yet, however.
Because I don't know what Zone 2 is, I had the students excavate it using a shovel-skim/piece-plot methodology. Shovel-skimming involves using shovels to carefully remove thin (e.g., 1/4" to 1/2") slices of sediment. This technique allows you to leave larger artifacts in place as you find them and keep an eye out for changes in sediment color and texture that could be associated with cultural features such as hearths, pits, or postholes. I had the students leave artifacts in place as they encountered them, marking them with a piece of orange flagging tape stuck in the ground with a nail. When the floor became too cluttered with artifacts, artifacts were piece-plotted (mapped individually) and removed. All the sediment that was removed with shovels was passed through 1/4" screen to catch smaller artifacts that weren't detected during the shoveling.
As I wrote last week, my hope for this Friday was that we would end the day being able to say with some confidence whether Zone 2 (the dark zone beneath the plowzone) is a buried plowzone or an intact cultural deposit. Unfortunately, I still don't have definitive evidence either way. Based on the day's work, however, I'm now leaning more toward the idea that we are, in fact, dealing with an unplowed prehistoric deposit.
If Zone 2 is a buried plowzone, we'll expect to see some evidence of plowing (e.g., plow scars or plow-truncated features) at the interface between the base of the zone and the underlying sediments. We're not to that interface in any of the block units yet, however.
Because I don't know what Zone 2 is, I had the students excavate it using a shovel-skim/piece-plot methodology. Shovel-skimming involves using shovels to carefully remove thin (e.g., 1/4" to 1/2") slices of sediment. This technique allows you to leave larger artifacts in place as you find them and keep an eye out for changes in sediment color and texture that could be associated with cultural features such as hearths, pits, or postholes. I had the students leave artifacts in place as they encountered them, marking them with a piece of orange flagging tape stuck in the ground with a nail. When the floor became too cluttered with artifacts, artifacts were piece-plotted (mapped individually) and removed. All the sediment that was removed with shovels was passed through 1/4" screen to catch smaller artifacts that weren't detected during the shoveling.
Shovel-skimming and piece-plotting of Zone 2 in the block units. Pieces of orange flagging tape mark artifact locations.
If Zone 2 turns out to be a buried plowzone, our careful excavation of it will have been largely an educational exercise (shovel skimming and piece-plotting are techniques that the students need to learn regardless, so that's fine). If it turns out to be an intact Mississippian midden deposit, however, I'll be happy that we excavated through it in a way that may help us learn something about its formation. The deposit has produced several rim sherds and at least one fragment of a pipe bowl. So far, there has been no sign of features originating within the deposit.
Rim sherd in situ. The rim edge is facing toward the top of the photo.
One of the pieces of information that has me thinking that Zone 2 may be a prehistoric midden is the view now available in the wall of Unit 9. Last week, I pointed at a small section of the base of Zone 2 and noted that it was more abrupt than one would expect in a naturally-formed sediment zone. On Friday, however, I took another look at the Unit 9 wall that Jim Legg is working on and it appears that that abrupt "straight" segment is more the exception than the rule. There also appear to be thin horizontal lenses of sediment within Zone 2, the presence of which seems inconsistent with a plowed deposit.
West wall of Unit 9, excavation in progress.
As shown in the photo, the excavation of Unit 9 is now down into the portion of the profile where lamellae become visible. These lamellae -- thin layers of clay-enriched sediment -- become thicker and more pronounced with depth in the profile. They are formed by the movement and accumulation of clay particles (here is an online article to get you started if you want to learn more about lamellae). Jim's excavation has yet to produce any diagnostic lithic artifacts (he's below the depth at which we're still expecting to find pottery) or evidence of intact features. He'll be down to the depth of what I think is a Middle/Late Archaic zone in a few more levels.
The weekly photo showing the excavation of Unit 9 in progress.
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