Establishing the seasonality of archaeological sites is critically important for understanding the life ways of pre-Contact peoples. In Connecticut, Katherine Brandon, Kevin McBride, and others have suggested that variability in Woodland period settlement-subsistence is not fully understood. As a result, both our understanding of pre-Contact settlement subsistence and the effect of European colonialism on Native life ways is impaired. Throughout the entire Northeast it would be valuable to develop techniques for considering seasonality at coastal sites in particular for several reasons: (1) as sea levels rise, these sites are rapidly vanishing, and with them valuable information that may never be recovered, (2) these sites may be among the most archaeologically visible, (3) the relationships of interior and coastal populations and their mobility remains enigmatic and may have been affected by European contact, (4) coastal sites often contain well-preserved faunal remains (bone and shell) that may be especially sensitive environmental indicators, (5) these analyses can be performed on shell from archival collections. In 2015, we were awarded a grant from the Douglas Jordan Testing, Dating, and Conservation Fund ("Jordan Fund") that was useful for establishing season of occupation at the Devil's Head Site, a Middle Woodland site in the Quoddy Region of northeastern Maine (Figure 1). Below is a brief description of our methodology and results.

Live Mya arenaria [soft-shell clams, popularly called "steamers" or "longnecks"] were collected and sampled to develop an accurate record of seasonal differences in modern soft-shelled clam, based on ¹⁸O values. These modern clams were obtained from beds that are directly adjacent to the Devil's Head archaeological site. Water samples were also collected, including salinity and temperature, at both high and low tide on the day modern clams were collected (July 4, 2014). Salinity was measured using a Salinity Refractometer, accurate to ±0.10% with salinity measured in parts per thousand (ppt); and temperature was measured using a digital thermometer, accurate to ±0.1ºC, at 1m below sea level. Archaeological Mya arenaria shells suitable for analysis (with the terminal growth band preserved on the ventral margin) were selected from collections provided from 2013 excavations (Hrynick and Webb 2014).

Both modern and archaeological shells were investigated to determine the structural composition of the shells using a Nicollet Thermo-Scientific iS5-FT-IR spectrometer (Figure 2). Samples were processed using the iD5 Diamond ATR setting. Samples of modern and archaeological shell were contrasted with known spectra of calcite and aragonite, to determine if the shells were susceptible to diagenetic alteration (Budd 1988; Brand 1989). The reference library used for   FTIR  ["Fourier Transform Infrared"] Spectroscopy analysis was made available by the Kimmel Center for Archaeological Science Infrared Standards Library, of the Weizmann Institute of Science, and infrared spectra methods followed Weiner (2010).


Modern and archaeological shells were collected and sampled along their terminal growth bands of the ventral margin for the most recent ¹⁸O values. Shells were incased in epoxy resin and then cut using a precision saw (Buehler Isomet 1000), cutting perpendicular to the chondrophore and ventral margin. The samples were then ground and polished with a Buehler Ecomet 3, providing a finely polished cross-section (Figure 3) for sampling.

Modern and archaeological shells were sampled at the terminal growth band of the ventral margin, and were first inspected to make sure that the margin was relatively intact. These shells were drilled sequentially using a hand held drill (Vogue 6000 Pro) using a 1 mm diamond drill bit, following the terminal growth band along the ventral margin and sampled at an approximate interval of 0.5 mm. Powdered carbonate samples were processed at the University of Arizona Environmental Isotope Laboratory, using a Thermo Finnigan MAT 252 coupled to a Kiel IV carbonate device. High-resolution digital images shells were obtained with a Nikon AZ100M Con-Focal Microscope, using a Digital Sight DSFI-1 camera with reflected light, with NIS Elements software. Shell preparation, FT-IR analysis, and image analysis were conducted at the Stable Isotope Laboratory and the Archaeobotany and Microphotography Laboratory, both at the University of Connecticut.

This work has been instrumental in our understanding of seasonal occupation at the Devil's Head Site. We have been able to estimate the season of occupation as either Fall or Spring, based on the stable isotope results and co-verified faunal analyses, which include identified taxa with cold season preferences. The results of this work have been presented at meetings of the Eastern States Archaeological Federation and Conference on New England Archaeology, and shared with FOSA members at a stable isotope workshop last year.*  The methods developed above are also currently being applied to Woodland archaeological sites on Block Island, RI with Kevin McBride, and are returning promising results that will be presented at the annual meetings for the Society for American Archaeology in 2017. We are also interested in applying these techniques to Connecticut pre-contact sites in the future. Our goal is to build a database of the region specific life-history and growth patterns of Mya arenaria, eventually establishing a high resolution record of paleoecologic data for New England. Stable isotope studies of archaeological shell middens offer a powerful way forward for archaeologists to identify seasonal occupation of sites, provides complementary information for traditional faunal analyses, and valuable data about the paleoecological setting of archaeological sites.

*Webmaster's Note1: To see pictures taken at the Workshop, please click Stable Isotope Workshop.

  Webmaster's Note2: For information on the equipment described in this article, click the links below:

• Nicollet Thermo-Scientific iS5-FT-IR
• iD5 Diamond ATR
• Buehler Isomet 1000 precision cutter
• Buehler Ecomet 3 polisher (YouTube video)
• Environmental Isotope Laboratory at the University of Arizona
• Finnigan 252 Isotope Ratio Mass Spectrometer (Note: MAH-252 info-link is to Stanford University, although readings are taken at the University of Arizona.)
• Kiel IV Carbonate Device
• Nikon AZ100M Confocal Microscope
• Digital Sight DS-Fi3 (orig. DSF-1) camera
• NIS Elements software
• Stable Isotope Laboratory at the University of Connecticut