The Mound House site is an approximately 5 hectare floodplain mound site located on a sand ridge adjacent the Illinois River in Greene County, Illinois. Prior to levee construction, three Middle Woodland mounds and two possible borrow pits arranged around a central, open space comprised the site. Adjacent these features is a large debris scatter associated with residential areas occupied by prehistoric peoples during their time at Mound House. The site is usually characterized as a Middle Woodland or “Hopewell” site due to the presence of multiple Middle Woodland mounds; however, archaeological investigations have demonstrated over 10,000 years of human occupation, from the Early Archaic period to the present. Late 19th and 20th century activities impacting site integrity include recurrent agricultural exploitation, creation of a large earthen levee, and construction of a 19th century tenant house on top of mound 1, that gives the site its name. As a result of these activities, mound 1 is the most readily discernible structure at the site. Plowing and levee construction have rendered mound 2 considerably less visible.
Mound House has been the focus of systematic investigation for nearly a half century by archaeologists associated with the CAA and its precursor organizations. Stuart Struever initiated investigations in the early 1960s. Intensive surface pickups were conducted in 1976 by James Bellis, and again in 1986 by the CAA’s Education Program, the latter of which included total surface pickup, limited test excavation, and collection of random surface finds of time-sensitive objects. Howard Winters and the New York University Field School excavated a trench into the western side of mound 1. Between 1998 and 2000, Jodie O’Gorman and the CAA Education Program excavated a macroblock west of mound 1.
In 1990, university field schools led by Jane Buikstra and colleagues engaged in long-term excavations at mounds 1 and 2. Initial efforts centered on mound 1. The western and southern portions of the site were most heavily explored, though sampling occurred at all peripheries of the tumulus. In 2001, fieldwork shifted to the northern and eastern margins of mound 2. At both structures, research was designed to focus on construction sequences and variability, and at mound 2, to assess the impact of recurrent plowing of the mounds.
Beginning in 2007, the Arizona State University Field School at the CAA has focused research on the residential portion of the site, particularly the debris concentrations north of mound 1 documented in both the 1976 and 1986 surveys. Our primary objectives are to investigate and document the long-term use, and natural and cultural modifications of the Mound House site over time. Of particular interest is the place of multi-community gathering sites on the Middle Woodland and post-Middle Woodland landscape. Central to resolving these issues is the detection of the temporal place and spatial organization of living spaces in themselves and in relation to the rest of the site; definition of structures and, if possible, activity areas, and seasonality, among others.
University field school staff and students conducted geophysical surveys of the habitation areas of the site during the 2007, 2008 and 2010 field seasons to detect in situ, subsurface anomalies indicative of prehistoric features within the high density surface scatter. These remote sensing methods allow archaeologists to target excavations within the large occupation area. Methods used include magnetometry, soil resistance survey, and ground penetrating radar. In addition, electrical resistance tomography (ERT) was used at mound 1 to investigate the vertical structure of the tumulus in 2010. ERT allows archaeologists to image and study the mound and its structures without disturbing this important resource.
To date, 18 test units have been excavated to groundtruth anomalies of interest. We focus our paper today on two specific areas: (1) a large magnetic anomaly (Feature 379) within the western debris scatter near the levee and (2) a series of small features suggestive of a prehistoric structure.
Feature 379 is a large anomaly (4.2 x 2.6 m) visible in both the resistance and magnetic data. Its widest dimensions are approximately 4.2 x 2.6 m. Excavation revealed the presence of a large, prehistoric pit feature that included multiple deposits of burnt and unburnt limestone, burnt and unburnt animal bone (e.g. fish, deer, turtle), mussel shell, charcoal, botanical remains, chipped stone debris, and Middle and Late Woodland period ceramic vessel fragments. Pottery varieties were predominantly Middle Woodland styles (Havana and Pike), though Late Woodland White Hall sherds were also present near the top of the feature.
The initial prehistoric pit of Feature 379 was also the largest. A wide basin was excavated into the original ground surface of the sand ridge. At least two, possibly three, smaller pits were later dug into the already filled pit. The presence of smaller, intrusive refuse pits into the larger feature is not surprising given the density of magnetic anomalies and surface scatter observed in this area of the site.
In sum, Feature 379 is a large refuse pit, with multiple depositional episodes and additional, intrusive fills. Debris associated with the feature are skewed toward ceramics, faunal material—both mammalian and aquatic—and burnt and unburnt limestone.
A second area of focus is a series of magnetic anomalies suggestive of a prehistoric structure. We have excavated six test units around this possible structure in order to characterize the geophysical anomalies, as well as the proposed interior and exterior of the structure. No evidence of prehistoric posts have been detected thus far. Multiple pit features have been encountered, and their contents are unlike Feature 379. Time-sensitive artifacts, particularly ceramics, have been a mix of Middle Woodland and Late Woodland sherds, though Middle Woodland sherds are most common. Vessel fragments included all Middle Woodland varieties: Havana, Hopewell, Pike and Baehr; Late Woodland sherds were White Hall. Faunal material is less common, with worked bone and turtle carapace being more frequent than in Feature 379. Extralocal lithics were also more common near the hypothesized structure.
There are clear differences between the features adjacent the hypothesized structure—whether it truly is a structure or not—and the high density area near Feature 379. The latter served as a refuse dump, as suggested by the subsistence-oriented materials recovered there. Burnt limestone, charcoal ash, fish and mammal bone, shell and primarily “culinary” vessel fragments (Pike and Havana sherds) suggest the disposal of unused foodstuffs and remnants of food processing.
In contrast, features around the hypothesized structure are more likely to contain fewer artifacts and a different range of materials. While pottery is common in both areas, including Havana, Pike, White Hall, Baehr and Hopewell vessel fragments are more frequent around the ”structure.” In addition, extralocal lithic raw materials, worked bone, sandstone abraders, mica and turtle shell were more frequently encountered. Whether the hypothesized structure was a domicile or not, archaeological residues there are more consistent with an activity space rather than a space dedicated to trash disposal.
Our statements on the residential area are, of course, tentative and additional excavation and analyses are needed enhance our resolution of Mound House occupations, and ultimately, the people who built, gathered and lived there. We look forward to sharing a more complete picture in the near future.
This work is ongoing! In 2013, the Arizona State University Archaeological Field School will return to Mound House and continue to investigate the habitation areas of Mound House. University students can join the adventure and receive college credit by applying to the ASU field school!