By Albert Pecora, Ph.D. and Jarrod Burks, Ph.D.
(with a contribution by Karen Leone, MA)
OVAI Contract Report #2008-58
August 20, 2008
The Phase II investigation of the Manns Site (33Le726) was designed to recover additional artifacts, to find objects and samples that could be used to pin down the time(s) of the site occupation, and to identify the presence of intact subsurface archaeological deposits. The ultimate purpose of the investigation was to determine if the site is eligible for the National Register of Historic Places, under criterion D. This was accomplished by employing a series of integrated methods: (1) a high density piece plot surface collection to augment the Phase I surface collection data, (2) a magnetic gradient survey to locate potential subsurface features, (3) a magnetic susceptibility survey to look for midden deposits, (4) limited deep testing to examine the vertical stratigraphy in this alluvial setting, and (5) partial excavation of a small sample of features.
Magnetic Gradient Survey
The magnetic gradient survey at 33Le726 covered 6,400 m2 and located at least 14 possible prehistoric features (Figure 1), six of which had probing (Oakfield soil cores) evaluations of “Good” or better (Figure 2), suggesting that these are probable archaeological features. These anomalies are primarily located on the highest part of the terrace. Three or four of the anomalies (the black anomalies in Figure 2) are probably earth ovens and they occur in a line. This clustering of earth ovens is common at sites that are occupied for long periods, perhaps an entire season or multiple consecutive seasons. As the use-life of one earth oven ends, the next is excavated just a few feet away. Earth ovens tend to be located in the yards of structures, usually from 10 to 40 meters away from the structures in open settlements (i.e., not large village sites with multiple households). If the magnetic susceptibility results are valid and the high susceptibility area on the southern slope of the terrace is a dumping area, then the building/house associated with these earth ovens was probably located someplace nearby on the highest part of the site. As such, Anomalies 10-15 could be located within or directly adjacent to the structure.
Phase I surface Data
The Phase I surface data (Figure 3) and the magnetic susceptibility data suggest that another, smaller occupation or activity area may be located to the southeast of the main cluster on top of the terrace. This area was not surveyed with the magnetometer, so we do not know if any possible pit features are present there. However, other areas of the site surveyed at this elevation did not contain significant magnetic anomalies. Perhaps this cluster is associated with an activity that did not require subsurface facilities?
Magnetic Anomaly Testing
Excavations at three magnetic anomalies resulted in the identification and partial excavation of three cultural features (Features 1-3). Each is a different type of thermal feature. Feature 1 is a large, steep-sided, flat bottomed pit that is lined with burnt earth and has a layer of fire-cracked rock (FCR) above a layer of charcoal at the bottom (Figure 4). Feature 1 also produced a substantial amount of lithic debris and a small amount of pottery that appears to date to the Late Woodland period, based on its thickness, surface treatment, and temper. Although these artifacts are not associated with the function of this feature (i.e., they are incidental trash), the FCR, burnt earth lining, and charcoal layer are directly related to the function of this pit as an earth oven.
Feature 2 is similar to Feature 1, but is smaller and lacks a burnt earth lining (Figure 4). Like Feature 1, Feature 2 contains a layer of FCR and a layer of charcoal. The charcoal layer in Feature 2, however, is above the FCR layer, suggesting that it was a slightly different type of earth oven. Feature 3 is a very large thermal rock feature that appears to have been created by placing fairly large rocks over top of a large, very hot fire (Figure 5). It is possible that Feature 3 was used to (1) heat rock for use in other thermal features or (2) as some type of cooking facility. It is also possible that Feature 3 is a thermal feature used to produce radiant heat for living space or sleeping space.
Archaeologists commonly assume that thermal features were used only for cooking or cooking-related activities. What is frequently overlooked is the potential use of thermal rock features for warmth and comfort, despite the fact that humans need warmth during cold seasons and hot rocks are a relatively efficient way to store and radiate heat. Early European explorers learned to produce radiant heat from native groups throughout North America by covering hot rocks with earth and hides.
An archaeobotanical study was conducted on samples collected from all three features. Because the archaeobotanical remains studied to date come from a small sample of features, it would be premature to use these results to make generalized statements about the overall use of plants at the site. Nevertheless, some initial observations are worth noting. Wood charcoal accounts for 99% of the botanical assemblage. The very high wood density may indicate long-term stay or it could just be the result of sampling features used for intensive thermal events. While the earth ovens (Features 1 and 2) produced nut, corn, squash, and EAC seeds, as well as a variety of wild fruit and ruderal taxa, Feature 3 showed evidence of a single thermal event and the pit was was filled immediately after. Feature 3 contained a very high density of wood, an incidental inclusion of nutshell, and nothing else. The nut and seed taxa recovered from the features are known to ripen from spring through the summer and fall months; however, we cannot use this information as concrete evidence of the season of occupation because nuts, EAC seeds, and some fruits can be stored for later use (and eventual burning). Archaeobotanical remains recovered from Features 1 and 2 are consistent with other assemblages from the area that are dated to the late Late Woodland and early Fort Ancient time periods in the Ohio River Valley. It is possible that horticultural practices were taking place at the site but investigation of a larger sample is needed.
In summary, three different types of thermal features were identified during the Phase II investigation of 33Le726. The magnetic gradient data and subsequent anomaly probing data indicate that at least 11 other features are present near the surface of the site. Numerous other features, especially post molds, are also likely to be present, though they were not detected in the magnetic gradient survey. These features, located at the base of the plowzone, date to the Late Woodland (Features 1 & 2) and Early Woodland (Feature 3) periods . Most of the projectile points from the surface of the site also date to the Early Woodland period. Manns Site Radiocarbon
Two deep backhoe trenches were excavated in the central and eastern portions of the site, on the highest part of the landform. These revealed the presence of a cultural horizon (Horizon IV) at 70-85cm below surface in Trench 1 near the center of the site (Figure 6), and at 62-78 cm below surface in Trench 2 in the eastern part of the site. This horizon contains large quantities of FCR and charcoal, and clearly predates the features located above it at the base of the plowzone. Horizon IV probably dates to the Late Archaic-Early Woodland period, as indicated by a radiocarbon date. The nearby Mabel Hall Site (33Le97), located on the same landform and northeast of 33Le726, also contains a Late Archaic-Early Woodland horizon at about 50 cm below surface, beneath the remains of the Late Woodland component that is located within and protruding down from the base of the plowzone. Buried cultural deposits have also been found 90 cm below surface at nearby site 33Le96, located north of 33Le726. It is very likely that some of the magnetic anomalies with poor, fair, or “nothing observed” probing results at 33Le726 are better quality features located in the deeper horizon that could not be adequately probed because they are too deep.