FINAL PROJECT REPORT: WOODLAND SEASONALITY ON THE NORTHERN COAST OF THE GULF OF MEXICO

Summary

The goal of this interdisciplinary project was to examine seasonal aspects of Woodland settlement patterns and resource use on the northern coast of the Gulf of Mexico from the perspective of two Woodland-period archaeological sites. The sites are located on the Alabama coast near Mobile Bay. Very little research has been conducted in this area for the Woodland period even though information about life during the Woodland period offers an important perspective on coastal life during the Mississippian period which followed it. Mississippian settlement patterns and subsistence strategies were presumably very different from those in the Woodland period in terms of mobility, social organization, and the role of domesticated plants. The project specifically looked at invertebrate and vertebrate remains from Middle and Late Woodland deposits at two Gulf coast sites: Plash Island (A.D. 325-642) and Bayou St. John (A.D. 650-1041). The multi-proxy study involved zooarchaeology of invertebrates and vertebrates, as well as stable isotope geochemistry [δ18O, δ13C, δ15N, 87Sr/86Sr], laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), and bulk ICP-MS analyses of oysters, rangias, coquinas, quahogs, hardhead catfishes, and gafftopsail catfishes. Molluscs dominate the Plash Island assemblage in terms of individuals though vertebrates contribute half of the biomass; molluscs dominate the Bayou St. John assemblage in terms of both individuals and biomass. Neither assemblage is highly diverse, though the Plash Island assemblage is more diverse than the Bayou St. John assemblage both in terms of sources of individuals and sources of biomass. People at Plash Island used shellfish and fish from a wider range of trophic levels and from higher trophic levels than did people at Bayou St. John. The more diverse strategy practiced at Plash Island extended to using more venison, which was a minor resource at Bayou St. John. Although people at both locations used over 70 invertebrate and vertebrate taxa, the people at Plash Island used those animals more evenly. Compared to the strategy practiced by people at Plash Island, people at Bayou St. John were more focused on estuarine resources, particularly molluscs, a focus reflected in the lower mean trophic level and the high percentages of individuals and biomass from trophic level 2.1 in the Bayou St. John assemblage. Most of the fish individuals in both assemblages are from fishes with the potential of maturing into large-bodied fishes. Inherently small-bodied fishes contribute very little of the biomass to either assemblage. Nonetheless, at least half of the sea catfishes, mullets, and drums in both assemblages had a Standard Length below 250 mm, indicating that they were small, young fish, though some individuals were considerably larger. The preferred fishing technology at both sites was based on mass-capture methods, such as weirs and small-gauged nets, but this was more pronounced at Bayou St. John than at Plash Island. Other technologies, such as large-gauged nets, likely were used to capture the large fish individuals in both assemblages. The Plash Island assemblage contains but one animal that has a markedly seasonal migratory habit such that its presence in the assemblage indicates a season when people too were present. In this case, the cownose ray only indicates a spring through fall, which is not sufficiently specific to reconstruct human residential patterns. The Bayou St. John assemblage contains somewhat more animals with more specific seasonal migratory habits; some of these animals are present near the site during warm weather and others are present during cool weather, indicating that Bayou St. John was occupied on a multi-seasonal basis. It also suggests a preference at both sites for using animals that were present at any time of the year, and seldom using highly seasonal molluscs or fishes. Stable oxygen isotope sequences in mollusc valves and fish otoliths indicate that people were present at both sites during all four seasons. Oxygen and carbon analysis of carbonate structures indicate that average stable oxygen and carbon isotope values of individual molluscs and fishes varied by taxon as well as by site. Isotopic analyses of carbon, nitrogen, and strontium indicate that archaeological deer specimens from Plash Island and Bayou St. John are all from the local biogeographic and geologic region and do not represent a resource brought to the site from a more inland location. For comparison, similar analyses were conducted on materials from the nearby, but inland, Corps site, which had a similar isotopic signature to the coastal materials. A parsimonious interpretation of this evidence may be that some, but not all, of the residents of coastal Alabama were mobile, but most of the mobility was restricted to the coastal strand, including Mobile Bay and the Mobile-Tensaw delta. Some of this mobility may have been seasonal, but, if so, it was based on more variable and subtle behaviors of the animals used, such as the reproductive cycles of the oysters, coquinas, sea catfishes, mullets, and drums, or on factors not related to animal periodicity.

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