Sunday, July 19, 2015

Defining the Upper Clay Floor

As noted in an earlier post, one of our greatest surprises this field season at Burrell Orchard was the discovery of a second clay floor. But unlike the first floor, this one was found just 15 to 20 cm (about 6 to 8 inches) below the surface! On most sites I have worked in northern Ohio, such a shallow feature would have been badly damaged, if not destroyed, by a century or more of plowing. But such was not the case at this amazing site. It seems that the area in which we are working is just a few meters beyond the most actively cultivated portion of the original farm. Of course, millennia of root growth, erosion, and rodent digging have taken their toll on this extremely rare piece of Ohio ancient history, but still this floor is amazingly well preserved after 4000 years (Figure 1).

Figure 1. Exposed southwest section of the upper clay floor. The excavation block shown here is three meters wide; the irregular gray stains on the floor are excavated pit features.

Based on our growing knowledge, this upper floor appears to be roughly oval in plan and measures at least four meters long (N-S) and three meters wide. The uncertainty is due to the fact that we have yet to expose the northern and eastern margins of the floor. Areas of orange-red clay, marking the locations of ancient fires, appear here and there across this clay surface. These burned patches may represent hearth features used by the occupants, who also dug small pits into the floor. Most of these pits contain very little in the way of artifacts, but some include bits of deer or other animal bone. Many may be small cache or storage pits. As these small pits were excavated, we noticed that the upper clay floor capped additional floor layers separated by thin lenses of midden soil (Figure 2). I noticed at least three of these subfloors in several excavated areas, and up to four floors were visible as small sections of yellow clay protruding here and there along the western margin of the upper floor.

Figure 2. Cross-section of small pit in the floor of the upper clay floor; note charcoal concentration in profile wall and yellow clay subfloor showing at the bottom left of the excavation.

Based on our experience with the deeper clay floor of Structure 1, we were careful to look for post molds lining the edges of the upper floor. After some careful troweling, we found several post molds forming an arc around the southwestern edge of the upper floor which may represent a wooden post structure built on top of the clay surface. A few days later, as we removed some of the surrounding midden soil, we exposed four or five post molds in a similar configuration along the edge of a deeper subfloor. This evidence may indicate that multiple structures were built and rebuilt, one on top of the other over decades or perhaps centuries at Burrell Orchard.

This discovery that several rebuilding episodes took place in this area of the site was expanded as we removed additional small sections of the upper floor to expose subfloor features, such as fired clay surfaces (hearths?) and FCR clusters. Small pits like the kind we recorded on the upper floor appear to have been constructed on these earlier structural floors. The most interesting of these was Feature 15-19, the small pit in which the fragment of slate bannerstone was deposited and later covered over by the subsequent, and final, clay floor. Thus, it seems likely that each layer of clay floor contains its own set of features which represent the activities of several generations of Native American families living at this site.

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