Excavation
and recovery of the burned keyhole structure.
A curious archaeological feature of
the Upper Ohio and the Susquehanna Valley of Pennsylvania is the
semi-subterranean free-standing keyhole structure (Smith 1976). Its general two
- dimensional shape can be easily compared to the keyhole of a door lock
(Figure 1). Attributed to the Late Woodland Period (circa AD. 1000 – 1550) the
keyhole structure has three principal parts: the body and rock filled pit
connected by a trench that is usually an upward ramped tunnel that extends to the
main body (Figure 2). One or more rows
of postmolds line the outer-most edge of keyholes the exception being the opening around the rock filled pit that
remained open for entry and exit purposes. Although the above ground three - dimensional
aspect of this feature type no longer exists due to the ravages of time and the
elements of nature, certain clues survive in the archaeological record that
provide us with a glimpse of their architecture and probable function.
Figure 1. Comparative
shapes of a keyhole feature and the keyhole of a door lock.
Figure 2. Generalized cross-section of a Late Woodland
keyhole structure.
The floor of the body is often
covered with carbonized material consisting of a flattened layer of charred
grass thatch overlain by burned sections of saplings that connect with the
post-lined pattern of postmolds encircling the wall of the body. Occasionally
these are cross - configured suggesting that the saplings were inserted into
the ground, then bent inward to form an arbor or igloo - like superstructure
over the body and ramp. Slabbed charred bark overlying the thatch and saplings
present inside many of the keyhole structures indicate that an outer layer of
bark was installed to insure a weather tight shell from wind, rain and snow. Some
examples show the presence of a relict drainage trench around the inside edge
of the body (Figure 3).
Figure 3. Excavation plan of a keyhole structure showing the
drainage trench.
The analysis
of more than seventy Late Woodland keyhole structures from the Unglaciated
Plateau of northcentral Pennsylvania (Herbstritt 1995) has yielded clues as to
their function. The long axis of these
structures is oriented along a northwest, west and southwest line that is also
the direction of the prevailing winds in this region. The insulated walls serve
as a protective barrier against these winds. A curious modification of the
free-standing keyhole structure is the keyhole compound presently known only
from those in the Unglaciated Plateau. The architectural design of this unique
type of keyhole feature is its incorporation of up to five keyholes joined to a
common rock pit (Figure 4).
Figure 4. Artist’s conception of a keyhole compound.
Fire altered rocks found in one or
more areas of the keyhole structure is another clue to their possible function
as a sweat lodge. Smith (1976) notes that rocks were commonly piled inside the
main body, set to one side near the wall making for easy access to and from the
semi-subterranean pit. The excavation of other keyhole structures in the West
Branch of the Susquehanna Valley contained abundant fire altered rock scattered
along the ramp joining the main body. These rocks always show evidence of
reddening on their fractured surfaces. Based on the contents of the keyhole
structure identified at the Fisher Farm site (36Ce35) in Centre county, Hatch
and Daugirda (1980) postulated that the feature functioned as a smoke house for
the curing of food stuffs.
Figure 5. Experimental reconstruction of the keyhole structure.
Results of experimental research
(Figure 5) on the, burning (Figure 6) and excavation of a reconstructed keyhole structure (see top), suggests that such features
were used as a food storage facilities (Herbstritt 1995). The interior
temperature of the structure could have been controlled over extended periods
of time during warmer conditions. Information from the experimental work and
follow-up excavation of the reconstructed keyhole demonstrated that the
archaeological evidence alone could not provide the necessary information
revealed through the experimental reconstruction. All said, given the present
state of knowledge it may be assumed that semi-subterranean keyhole structures
were likely multi-functional as their uses probably varied over the course of
the year from sweat lodges to smokeries to food storage structures.
Figure 6. Burning of the keyhole structure.
We hope that you have enjoyed this
brief presentation on keyholes from the archaeological and experimental
perspectives. Learning from the past through archaeological investigations or
experimental archaeology is important to understanding and appreciating our
cultural heritage. Please help us to preserve the past by collecting
responsibly and respecting our preservation laws. Do join us next time when we will again bring
you yet another fascinating topic on This Week in Pennsylvania Archaeology.
REFERENCES
Hatch, James W. and Joyce Daugirda
1980 The
Semi-Subterranean Keyhole Structure at Fisher Farm – Feature 28. The Fisher
farm Site: A Late Woodland Hamlet in Context. Edited by James W. Hatch. Occasional Papers, No.12. The
Pennsylvania State University, Department of Anthropology.
Herbstritt, James T.
1995 Reliving
Prehistory: The Experimental Archaeology of a Keyhole Structure. Paper
presented at the 66th Annual Meeting of the Society for Pennsylvania, Inc.
Morgantown.
Smith, Ira F.
1976 A Functional Interpretation of Keyhole
Structures in the Northeast. Pennsylvania
Archaeologist 46(1-2): 1-12.
For more information, visit
PAarchaeology.state.pa.us or the Hall of Anthropology and Archaeology at
The State Museum of Pennsylvania .
