Modoc Rock Shelter Site, IL (11R5) 1980 Excavation Project

Summary

This project includes data from the 1980 excavation season at Modoc Rock Shelter (11R5). The 1980 archaeological excavation was conducted by Drs. Bonnie Styles and Melvin Fowler under the auspices of the Illinois State Museum and the University of Wisconsin-Milwaukee. Funding was provided by a grant from the Department of Interior (Heritage Conservation and Recreation Service) to the Illinois State Museum Society. Initial excavations at Modoc were conducted in 1952, 1953, 1955, and 1956 by Dr. Melvin Fowler under the auspices of the Illinois State Museum and the University of Chicago.

During the 1980 field season, backdirt from the 1956 west shelter excavations and from the 1953 deep test excavation in the central pit of the Main Shelter was removed and the profiles were scraped to allow a reassessment of the stratigraphic sequences and collection of radiocarbon, pollen, and gastropod samples from the profiles. New excavations in 1980 were only conducted in the West Shelter Area. Eleven 1.5 m by 1.5 m units (Units A-K) were excavated to approximate the size of the 5-foot squares excavated in 1956. Excavation levels followed the stratigraphic divisions evident in the profiles and did not exceed 10 cm in thickness. The 1980 work refined the radiocarbon chronology, contributed analyses of small-scale remains recovered through water screening and flotation, and refined the understanding of environmental and cultural change.

Preservation of remains was excellent. Recovery methods were as follows. A 1/2 liter sediment sample and a 15 liter flotation sample were removed from each general excavation and feature level. Any remaining sediments from the excavation unit were processed through nested 1/4 inch and 1/16 inch mesh screens with the aid of pressured water (waterscreening). Remains were dried and bagged separately in the field. Flotation samples were processed in the field using a Patty Jo Watson-style flotation barrel with a forced-water source inside the lower, larger barrel. The heavy fraction (rock, shells, bones, and other dense cultural material) was collected from the bottom of the inner barrel equipped with 1/16" mesh. The light fraction (seeds, charcoal, and other light-density remains) floated and was collected in a fine mesh screen (1/40"). Residue from each fraction was dried and bagged separately in the field.

113 charcoal samples were collected for radiocarbon assay. Of these, 16 were submitted to the Illinois State Geological Survey for assay. Samples from fired surfaces were collected for archaeomagnetic dating. Sediment samples were collected from each excavation level for chemical and physical analysis. Sediment columns were taken from the profiles. Columns were taken from the south and east profiles of the 1956 excavation in the West Shelter area. Solid core soil samples were taken from the area surrounding the rock shelter. In addition, an approximately 4 liter sediment sample was collected from each of the major stratigraphic zones in the West Shelter for analysis of gastropods (freshwater and terrestrial snails).

Vertebrate faunal remains reported here were recovered via water-screening through the nested 1/4 inch and 1/16 inch mesh screens. Gastropods reported here were from the 4-liter stratigraphic gastropod samples and from the 15 liter bulk soil samples.

Analysis of the 1980 data revealed stratigraphic differences between the west and central areas of the site, which when combined with the new radiocarbon chronology, allowed proper grouping of materials by age. Deposits in the central area are at least 1000 years younger than deposits at equivalent elevations in the west area. Integration of data derived from lithic artifacts, faunal remains, and archaeobotanical remains indicates that site function shifted from short-term encampments in the Early Archaic to a longer-term base camp during the Middle Archaic. Late Archaic materials indicated a more limited or specialized site function. Paleoenvironmental data document a shift from a wet closed forest setting during the Early Holocene to a drier more open forest setting during the Middle Holocene.

Macrofaunal remains (1/4" waterscreen samples) were identified by Holly Carr and Bonnie W. Styles using the Illinois State Museum's Comparative Faunal Collections and verified by Drs. Bonnie Styles (freshwater mussels, fish, amphibians, reptiles, birds, and large and medium mammals) and James R. Purdue of the Illinois State Museum (for small mammals). Whole samples were analyzed. Data were recorded in an electronic database.

Microfaunal remains from the 1/16" waterscreen samples were identified in 1981. James R. Purdue identified the mammals and Bonnie Styles identified the fish. Bonnie Styles recorded other classes of fauna, primarily in gross categories: turtles, other reptiles, amphibians, birds, indeterminate vertebrates, pelecypoda (freshwater mussels), decapoda (crayfish), and coleoptera (beetles). The 1/16" waterscreen samples were divided into 1/4 and 3/4 subsamples using a geological riffle splitter. Only 1/4 subsamples were examined and tabulated; data were recorded on paper forms. All provenience and sample data were recorded on the forms. For the 1/16" waterscreen subsamples, the taxon, element, portion, symmetry, and count were systematically recorded. Comments on burning, preservation, age, gnawing, butchering marks, and fish length were recorded in the comments section. Quantification of attributes recorded in the comments column is less precise than for the 1/4" waterscreen fauna. Mona Colburn entered the data from the paper forms for the 1/16" waterscreen microfauna into an electronic database in 2016.

Dr. David Barreis (University of Wisconsin-Madison) and James Theler (University of Wisconsin-Madison) analyzed gastropods from 4 liter samples of sediment from the major stratigraphic zones exposed in the profiles of the West Shelter. James Theler analyzed gastropods from flotation samples from Units C, D, and F. from the 1980 West Shelter excavations.

This Resource is Part of the Following Collections

• Prairie Peninsula   •
• Modoc Rock Shelter (11R5), Randolph County, Illinois   •
• Eastern Archaic Faunal Working Group

Keywords

Temporal Coverage

Radiocarbon Date: 7770 to 7390 (West Shelter, Stratum WS-6, Unit C, F505, ISGS-813, Elevation 120.81-120.66 meters above sea level, wood charcoal and charred nut shell)

Radiocarbon Date: 9550 to 9090 (West Shelter, Stratum WS-15, Unit C, surface, ISGS 820, Elevation 118.52-118.45 meters above sea level, wood charcoal and charred nut shell, potential for contamination)

Radiocarbon Date: 7370 to 7090 (West Shelter, Stratum WS-5A, Unit C, F503, ISGS-840, Elevation 120.91-120.86 meters above sea level, wood charcoal and charred nut shell)

Radiocarbon Date: 8150 to 7870 (West Shelter, Stratum WS-7A/8, Unit D, F516, ISGS-830, Elevation 120.45-120.41 meters above sea level, wood charcoal)

Radiocarbon Date: 8250 to 7810 (West Shelter, Stratum WS-9/10, Profile, Feature 20/22, ISGS-1299, Elevation 120.37-119.97 above sea level, wood charcoal)

Radiocarbon Date: 9140 to 8700 (West Shelter, Stratum WS-16, Units C,G, and I, F85, ISGS-740, Elevation 117.77-117.69 meters above sea level, wood charcoal)

Radiocarbon Date: 8830 to 8530 (West Shelter, Stratum WS-13A, Unit C, ISGS -797, 118.95-118.85 meters above sea level, Wood charcoal and charred nut shell)

Radiocarbon Date: 7310 to 6950 (West Shelter, Stratum WS-5A, Unit C, F507, ISGS-831, Elevation 120.69-120.34 meters above sea level, wood charcoal and charred nut shell)

Radiocarbon Date: 9030 to 8750 (West Shelter, Stratum WS-15, Unit C, F87, ISGS 747, Elevation 118.37-118.35 meters above sea level, wood charcoal)

Radiocarbon Date: 8350 to 8190 (West Shelter, Stratum WS-10, Unit C, ISGS-808, Elevation 119.80-119.69 meters above sea level, Wood charcoal)

Radiocarbon Date: 8850 to 8570 (West Shleter, Stratum WS-13, Unit C, F59, ISGS-780, Elevation 118.69-118.66 meters above sea level, wood charcoal)

Spatial Coverage

Individual & Institutional Roles

Contact(s): Mona Colburn

Field Director(s): Steven Ahler

Project Director(s): Bonnie Styles; Melvin L. Fowler

Repository(s): Illinois State Museum

Source Collections

Illinois State Museum