Friday, June 23, 2017

Charnel Structures, Petal Structures and the Disappearing Monongahela Culture

Figure 1

The Monongahela were a Late Prehistoric group of people who lived in the lower Upper Ohio Valley of southwestern Pennsylvania from circa A.D. 1050 - A.D. 1615/35. Many of their settlements were built on bluffs overlooking large river systems while others were hidden away on low terraces adjacent to smaller waterways. The typical Monongahela village can be described as a single or double ring of small round houses (domestic/storage/burial zone). Many of the houses also had a semi-subterranean pit that was free-standing or attached to the wall (Figure 1). Houses were built around an open plaza (communal zone) encircled by one or more gated palisades (defensive zone). An encircling ditch-trench, surrounding the palisade, was used as a convenient place for discarding trash (disposal zone) (Figure 2). Most villages covered an acre or more though some were enormous, approaching  nine acres in size. Village locations were re-used over time as is indicated by overlapping palisades and midden features of accumulated trash at some sites (Figure 3).

Figure 2

Figure 3

               During the 15th century the internal composition of Monongahela villages changed to include a single, larger-than-average, round house, a pattern that over time appears to have moved toward the outermost ring of houses. This type of structure was a place where some of the dead were interred, frequently exceeding more than 10 individuals (Figure 4). These so-called charnel structures may have been reserved principally for individuals, who were perhaps considered prominent members of the community i.e. headmen or others serving special roles or perhaps members of a certain lineage. There was, however, no general preference as to the gender or age of the interred individuals. By the late 16th century houses for the dead disappear from the archaeological record and infants and children are the only classes of individuals being continually interred in the common village household. Adult and elderly Monongahelans were evidently buried elsewhere which marks a defining moment in Monongahela mortuary practices from earlier times.

Figure 4

                Curiously, by the proto-Historic period circa A.D 1550/75 Monongahelans began building large round-shaped buildings with semi-subterranean petal-shaped appendages at some of their settlements (Figure 5). Petal structures, like the smaller size Monongahela households had a centrally placed hearth where residents prepared and processed food. At colder temperatures, the hearth became the sole source of radiating heat both in households and petal structures. The archaeology at these sites suggests that newer petal-structures were often rebuilt on or very near the footprint of older ones thereby demonstrating a desire to reuse the same general locations through time.
Figure 5

The number of appendages associated with petal structures varied widely. For example, at Sony, Throckmorton and the Foley Farm sites, archaeologists found as few as 11 to as many as 24 appendages attached to petal structures. An opening or doorway always appears on the northeast to southeast side of the petal structure. When petal structures were first incorporated into the ring of houses, as at the Throckmorton site, the doorway always faced toward the village plaza (Figure 6). The appendages associated with houses and larger petal structures are recognizably different in that the latter generally had a greater length ratio of nearly 2 to 1.
Figure 6

There is a long-standing assumption by archaeologists that semi-subterranean structural features, whether free standing or otherwise, were used for storage of perishable foods and, no doubt, a resident’s personal effects. The function and purpose of Monongahela petal structures may never be satisfactorily explained since their morphology is generally comparable to Monongahela dwellings. That petal structures abruptly appear in southwestern Pennsylvania at the very end of the Late Prehistoric period when goods of the European trade begin to filter into the region from the eastern coast of North America seems clear from the archaeological evidence. With these changes in village architecture came disease, sickness and often death, to people who had little resistance to biological vectors of calamity.

In summary, it is interesting to note that Monongahela villages grew from small settlements containing a half dozen or so houses to enormous settlements covering many acres followed by a recognizable reduction in village size in the closing years of the Late Prehistoric period with the appearance of petal structures and the disappearance of charnel structures in the Monongahela core area of southwestern Pennsylvania. These archaeologically deduced observations leave us with many unanswered questions regarding the driving forces that forever changed the settlement, community and mortuary patterns of a disappearing people called Monongahela.

We hope you’ve enjoyed this glimpse into the past at the Monongahela peoples who occupied Pennsylvania during prehistoric times and invite you to visit other blogs on TWIPA which discuss the Monongahela.   Understanding and exploring our archaeological heritage is pivotal to our understanding of human behavior and our ability to change and adapt over time- just as the Monongahela peoples did for hundreds of years.


Davis, Christine E. and Amy K. Wilks
1997       Phase III Data Recovery Sony Site, 36WM151, Westmoreland County, Pennsylvania. A Cultural Resource Management Report prepared for the Westmoreland County Industrial Development Corporation.

Dragoo, Don
1955     Excavations at the Johnston Site. Pennsylvania Archaeologist 25(2): 86-141.

            George, Richard L.
1983       The Gnagey Site and the Monongahela Occupation of the Somerset Plateau. Pennsylvania Archaeologist 53(4): 1-92.

Herbstritt, James T.
2003       Foley Farm: The Importance of Architecture and the Demise of the Monongahelans. Pennsylvania Archaeologist 73(1): 8-54.

Mayer-Oakes, William J.
1955       Prehistory of the Upper Ohio Valley; An Introductory Archaeological Study. Anthropological Series No.2. Annals of the Carnegie Museum.

NPW Consultants, Inc.
1983       Excavations at Two Monongahela Sites: Late Woodland Gensler (36GR63) and Proto-Historic Throckmorton (36GR160). Report submitted to Consolidation Coal Company, Pittsburgh, Pennsylvania

For more information, visit or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .

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