Sunday, June 13, 2010

New Dates on Heckleman Features

Over the winter, we submitted five organic samples from the 2009 excavations at Heckleman for radiocarbon dating. Each sample was selected from features that were thought to date to different occupations of the site, and this proved to be the case, for the most part. We were particularly interested in the age of the oval enclosure trench. Based on the rather thick, flat-bottomed vessel fragment and one knob handle that were found during excavation, we concluded that the trench was filled sometime during the Early Woodland period. A fragment of deer bone from this trench (Feature 09-10) returned a calibrated median date of 195 B.C., which is right on the mark. We also dated some deer bone from the nearby Feature 09-20, which contained similar forms of pottery and also a bladelet, and the result was nearly the same at 185 B.C.

I also was very interested in getting a date on Feature 09-19 which intruded into the fill of the enclosure trench. We dated a fragment of deer astragalus or ankle bone from this pit to 110 B.C., not terribly later than the other features but perhaps a generation or two later. So, based on this information, we have a good general sequence of events which began with the digging of the enclosure trench by about 200 B.C.—but who knows how much earlier—followed by a rather quick filling of the trench with debris (pottery sherds, a few used-up stone tools, a bit of animal bone, charcoal, and fire-cracked rock). The fill of the pit showed two to three distinct fill layers or strata which indicates that the filling took place in several episodes. Once the trench was filled, the folks that followed used the space for the construction of storage pits and other features. Perhaps this sequence reflects the use and then abandonment of the enclosure by Early Woodland people, but as yet, we still don’t know what the enclosure was used for or even when it was constructed.

The fourth radiocarbon date was run on a sample of charcoal from Feature 09-31, a small basin-shaped pit found inside the enclosure during the last week of the 2009 season. This is the pit that contained the fragmented siltstone gorget (see earlier post). The thick charcoal layer from which the dated sample was taken can be seen in the profile image shown below.

To my mild surprise, the median calibrated date on this sample was A.D. 525, significantly later than the Early Woodland occupation. This date marks the transition from Middle to Late Woodland societies in the region and shows that the former enclosure space was reused by much later inhabitants. The pit itself showed evidence of burning and, perhaps, use as a cooking pit. Numerous large and small post molds were recorded in the vicinity of this pit, which may indicate the presence of a structure; however, we cannot say at this time.

Finally, we dated the pit structure (Feature 09-04) using a carbonized hickory nut hull from a small concentration found near the floor of the house. The result was about what we expected, dating the structure to a mean calibrated date of A.D. 1535. The thin, well-made, grit-tempered pottery found in the fill of this structure, along with the Madison triangular points, could easily date to this era, the latter half of the Late Prehistoric period in northern Ohio. This final date most likely provides evidence of the last occupation of the Heckleman site, since no other sites in the Huron Valley date any later in time.