Sunday, March 25, 2012

Firelands Ground Sloth

One of our other recent projects in Archaeology at the CMNH is the study of the Firelands Ground Sloth.  This project involved the documentation of 41 stone tool cut marks found on the femur (thigh bone) of an extinct Ice Age animal called the Jefferson's Ground Sloth (Megalonyx jeffersonii).  Ten bones of this creature were found several years ago in the attic of the Firelands Historical Society Museum in Norwalk, Ohio by Matt Burr.  Matt showed me the bones five years ago, and since then, we have been examining the traces of stone cutting tools used to butcher the animal.  The bones have been dated to more than 13,000 years old and represent the first evidence for the use of this particular Ice Age animal by ancient humans in Ohio.   The results of our work were recently published in the journal World Archaeology (vol. 44, no. 1, pp. 75–101).   Images of the femur and other illustrations can be seen on the CMNH website.  A nicely done story on the project was produced by WKSU radio.

Sunday, March 18, 2012

A Late Woodland House

One of our most recent discoveries from the Heckleman site is an early Late Woodland house structure.   "Structure 2," as it is designated, only came to light this winter as I was examining the post mold data from the eastern end of the southern bulldozer transect.  By comparing the various diameter and depth measurements for each of the hundreds of post molds found in this area, I identified the outline of a rectangular structure with rounded corners.  This outline is not a figure of my imagination--which can occur after hours of staring at post mold patterns--but rather consisted of a set of large post molds that were significantly (i.e., greater than one standard deviation from the mean) wider and deeper than the post molds around them.   As the diagram below shows, this outline encompasses at least two clusters of circular to oval pit features, as well as several other large post molds.
During excavation of this area, we exposed a thin layer of what appeared to be midden soil.  This soil was slightly darker in color than the subsoil and contained bits of FCR, charcoal, chert flakes, and a few small animal bones.  As can be seen from the dashed outline in the figure above, this irregular patch of soil lies completely within the outline of Structure 2, which suggests that it is associated with the structure.  My best guess for now is that this midden layer is a remnant of debris that once covered at least a portion of the structure floor.  Of particular interest is the fact that this midden layer completely obscured Feature 11-39, a large post pit, until it (the midden) was removed.  This means that Feature 11-39 was dug and eventually back-filled before the floor debris was laid down.  If, as I have described earlier, these large pits held stout wooden posts, then it would seem that this particular post was removed before the house was occupied.

Fragments of carbonized nutshell and charcoal were recovered from several of the pit features within Structure 2.  Several of this pits, like Features 11-19, and 11-35, contained large concentrations of pot sherds from one or two vessels, suggesting possible storage functions for these pits.  Small pieces of carbonized nutshell and charcoal were recovered from four of the pits within Structure 2  and from a post mold in the western wall line.   These samples produced a calibrated median radiocarbon date range of A.D. 525 to 665, which places the occupation of this structure in the early Late Woodland period, just a century or two after the Hopewell Middle Woodland settlement of the site.   This early Late Woodland period in north-central Ohio is called the Green Creek phase and is marked by the construction of very thin, finely cord-marked (Green Creek Cordmarked) vessels, very much like the fine example found in Feature 11-35 and shown below.