Sunday, June 21, 2009

From Trash Pit to Pit House

In my last post, I described the discovery of Feature 09-04, a large concentration of charcoal and ash that produced a distinct magnetic signature. Upon excavation, this feature produced rather large quantities of artifacts and food remains such as animal bones. But late this past week, we realized that this feature is not just an over-sized garbage dump, but something else entirely. As we quarter-sectioned this big stain, we identified a concentration of ash deposits and burned soil near the center, a classic hearth feature. Then, at the outside edge of the feature stain, we discovered a ring of regularly-spaced post molds which most likely represent a superstructure of some kind.

Now, why would the prehistoric inhabitants of this site construct a roof over their trash pit? Of course they would not, but they would build a roof over a dwelling. Based on these clues, we concluded that Feature 09-04 is a pit house, a small structure used by just a few people.

Similar pit houses have been found at Late Woodland sites in Illinois and Pennsylvania. Our own excavations at the White Fort site in 2002, exposed six such structures. All have the distinctive "key-hole" plan form which consists of a round to oval basin with an elongated entryway. The image of Feature 09-04 below shows this characteristic form.

The quarter section profiles reveal a rather complex stratigraphy in the fill of this pit. As shown in the image below, most of the fill consists of lenses of trash deposits and sandy soil which were dumped into the pit after the dwelling was abandoned. Beneath this fill are several thin strata of carbon-rich soil which represent the successive floor levels of the dwelling. A distinct floor layer is indicated by the red arrow in the image below.

The central hearth feature also exhibits distinct layering of ash and burned sand which indicates that successive fires were constructed during each occupation. The distinctive entryway points to the southeast and may have been constructed to prevent large quantities of warm air from escaping the interior. This would have been an important consideration if the dwelling was inhabited during the winter months, a likely conclusion. The few decorated rim sherds recovered from the pit house indicate that it was inhabited during the fourteenth or fifteenth centuries A.D.