Determining the habitats of mollusk collection at the Sapelo Island shell ring complex, Georgia, USA using oxygen isotope sclerochronology

Sequential oxygen isotope analysis was performed on Mercenaria spp. (n = 41) and Crassostrea virginica (n = 17) valves excavated from the Sapelo Island Shell Ring complex, coastal Georgia, USA. The data were analyzed to determine the habitats in which the mollusks were harvested in order to gain insight into the subsistence practices of the site occupants. The rationale for this study is based on the observation that temperatures are similar in all of the habitats surrounding the island, but the δ¹⁸O_water trends across the habitats co-vary with salinity. Accordingly, the shells grown in these habitats contain sinusoidal oscillations in δ¹⁸O through ontogeny due primarily to seasonal temperature variation, but the absolute values reflect the salinity ranges of each habitat. Assuming a relatively constant oxygen isotope/salinity gradient since the time of site occupation, it appears that both of these mollusks were exploited over nearly the full range of their salinity tolerances. While a precise estimate of travel distance during collection cannot be made, these data suggest that mollusks were harvested at distances from the site greater than would be predicted using terrestrial foraging models. In addition to providing insight into past subsistence strategies in this region, this research establishes a new method of assessing catchment area and mobility practices.     

OYSTER DEMOGRAPHICS AND THE CREATION OF COASTAL MONUMENTS AT ROBERTS ISLAND MOUND COMPLEX,FLORIDA

Abstract

Anthropogenic coastal landscapes often incorporate shell, a durable remnant of subsistence activity. Collection, consumption, and even feasting can thus contribute to histories of site formation and mound construction. This research assesses how oyster consumption related to the creation of Mound A, a shell mound at the Roberts Island Shell Mound Complex in Citrus County, Florida, is differentiated from the instances of oyster consumption that resulted in the midden constituting the rest of the island. I compare the size of shell remains from mound and off-mound midden contexts to assess variation in the sizes represented across the samples, stratigraphic variation within each context, and evidence for directional change indicative of over-exploitation. I identify a relationship of dependence between shell size and stratigraphic depth in off-mound samples that does not appear in mound samples, suggesting a relatively short period of time for the accumulation of mound deposit oyster shells. The findings of this study point to mound construction at Roberts Island Shell Mound Complex as a distinct and deliberate activity, with the construction event likely sharing importance with the community aggregation and consumption that facilitated it.     

Archaeological Site or Natural Marine Community? Excavation of a Submerged Shell Mound in Ninigret Pond,Rhode Island

ABSTRACT

Submerged shell midden sites and natural shell deposits can have similar characteristics and can be difficult to distinguish archaeologically. We excavated two test units from a large (at least 35 m×70 m) submerged shell mound in Fort Neck Cove in southern Rhode Island to assess whether it was natural or cultural in origin. This mound had been recognized as a potential archaeological feature as early as the 1970s. Excavation, radiocarbon dating, and subsequent laboratory analysis of excavated materials suggest that the mound was a natural oyster reef rather than a submerged archaeological site. No artifacts were found; there was no clear evidence for human modification of any shells; small species that would not have been targeted as food were present; and δ¹³C values of oyster shells from the mound were consistent with freshwater input into their growth environment, suggesting that they grew in an estuarine environment that did not exist prior to the inundation of the ponds. The stratigraphically oldest radiocarbon date we could obtain (430–190 cal BP, 2σ range), from 70 cm below the pond floor, placed deposition of shells at least 3,000 years after the inundation of the pond. The excavation methods that we used and the process of testing, irrespective of whether the feature is cultural, are valuable contributions to the methodological literature on submerged site archaeology and help provide insight for other researchers working to discern natural from cultural shell midden sites.     

Comparison of mangrove oyster shells lengths harvested in Cuba during the pre-Columbian era and the present day

Abstract

The Mangrove oyster [Crassostrea rhizophorae (Guilding, 1828)] was intensely harvested in the pre-Columbian era by an aboriginal group of hunters and gatherers known as the Ciboney who lived exclusively in Western Cuba. During a comprehensive study of mangrove oyster fishing areas it was of interest to compare the population characteristics under contemporary exploitation with those in pre-Columbian times and for that purpose two samples were used: one from a Ciboney midden in an archeological site 3 km inland from the Jaruco River mouth and another from a commercially exploited population in the ecologically similar Tacajó River. The samples were studied with a ‘shell classifier’ of original design resulting in a mean length of 51.8 ± 2.5 mm for the midden shells and 51.0 ± 3.1 mm for the contemporary sample. Both values were not statistically different for any P > 0.10 meaning that the two populations they came from had similar characteristics. It was also concluded that the Ciboney's manual harvesting exerted less negative anthropogenic pressure on the mangrove oysters’ populations than the contemporary commercial practices based on the use of metal instruments to gather the oysters along with the mangrove aerial roots they are attached to. This latter conclusion is based on the fact that oyster shells 41–80 mm long from the midden are 12% more abundant than in the modern sample, in spite of 500 years of weathering.     

The Changing Exploitation of Oysters (Ostrea edulis L. 1758) in Late Medieval and Early Modern England: A Case Study from Dudley Castle,West Midlands

ABSTRACT

Analysis of over 4000 complete left oyster valves from late medieval and post-medieval Dudley Castle reveals the changing role of this perishable luxury over a 700-year period. Throughout the occupation, it seems that oysters were used as ingredients rather than served raw in the shell. A greater reliance on oyster consumption is apparent in the later fourteenth century, perhaps reflecting a more diverse diet amongst the aristocracy in the wake of the Black Death. An increased preference for mussels and whelks is also attested in the Tudor and early modern periods, reflecting changing perceptions of these foods.

Overall, it is likely that natural beds were exploited throughout the time that oysters were being brought to Dudley Castle; however, the evidence demonstrates a shift from limited exploitation of natural inter-tidal sources in the eleventh century towards the dredging of sub-littoral beds in later periods, with some possible translocation of oyster stock. Changes in the shape, size and appearance of the oyster shells suggest the source locales from which the oysters derived changed through time. A notable shift occurred in the fourteenth century, which could reflect changes in supply brought about by altered tenancy at Dudley Castle and/or disruptions to trade brought about by the Black Death. Future biochemical analyses are recommended to provide greater clarity on the origin of those sources.     

REFINING ESTIMATES FOR THE SEASON OF SHELLFISH COLLECTION ON THE PACIFIC NORTHWEST COAST: APPLYING HIGH‐RESOLUTION STABLE OXYGEN ISOTOPE ANALYSIS AND SCLEROCHRONOLOGY

Stable oxygen isotopes from estuarine bivalve carbonate from Saxidomus gigantea were analysed combined with high‐resolution sclerochronology from modern and archaeological shells from British Columbia, Canada, to determine the seasonality of shellfish collection from the archaeological site of Namu. The combination of high‐resolution sclerochronology and a micro‐milled sampling strategy for δ¹⁸O analysis permits a precise estimate of archaeological seasonality, because seasonal freshwater influxes and changes in temperature have dual effects on the δ¹⁸O value of the shell. Sclerochronological analysis identifies the timing and duration of growth that is temporally aligned to stable oxygen isotope results, since δ¹⁸O_shell appears to be strongly influenced by seasonal inputs of very low δ¹⁸O snowmelt‐water from adjacent coastal mountain ranges. The results show that shellfish were collected year‐round at this site over a 4000‐year period, and these data combined with other zooarchaeological lines of evidence support the interpretation of year‐round occupation.     

Temperature‐dependent Li isotope ratios in Appalachian Plateau and Gulf Coast Sedimentary Basin saline water

Lithium (Li) concentrations of produced water from unconventional (horizontally drilled and hydraulically fractured shale) and conventional gas wells in Devonian reservoirs in the Appalachian Plateau region of western Pennsylvania range from 0.6 to 17 mmol kg^?1, and Li isotope ratios, expressed as in δ⁷Li, range from +8.2 to +15‰. Li concentrations are as high as 40 mmol kg^?1 in produced waters from Plio‐Pleistocene through Jurassic‐aged reservoirs in the Gulf Coast Sedimentary Basin analyzed for this study, and δ⁷Li values range from about +4.2 to +16.6‰. Because of charge‐balance constraints and rock buffering, Li concentrations in saline waters from sedimentary basins throughout the world (including this study) are generally positively correlated with chloride (Cl), the dominant anion in these fluids. Li concentrations also vary with depth, although the extent of depth dependence differs among sedimentary basins. In general, Li concentrations are higher than expected from seawater or evaporation of seawater and therefore require water–mineral reactions that remove lithium from the minerals. Li isotope ratios in these produced waters vary inversely with temperature. However, calculations of temperature‐dependent fractionation of δ⁷Li between average shale δ⁷Li (?0.7‰) and water result in δ⁷Li_water that is more positive than that of most produced waters. This suggests that aqueous δ⁷Li may reflect transport of water from depth and/or reaction with rocks having δ⁷Li lighter than average shale.     

PASTE CHARACTERIZATION OF WEEDEN ISLAND POTTERY FROM KOLOMOKI AND ITS IMPLICATIONS FOR SPECIALIZED PRODUCTION

Abstract

We report the results of a petrographic analysis of pottery from Kolomoki, a Middle and Late Woodland period mound and village complex in southwestern Georgia. Thin sections of 65 sherds representing several prestige and utilitarian Weeden Island pottery types, from both domestic (midden) and ceremonial (mound) contexts, were obtained. For comparison, we also analyzed samples from a few potential clay sources. We characterize the range of variability in paste/resource groupings present in the Kolomoki assemblage and use these data to address patterns of manufacture and exchange of Weeden Island pottery through comparisons to thin sections of comparable types from the McKeithen site and other Weeden Island sites in the region.     

Mesolithic shellfish exploitation in SW Italy: seasonal evidence from the oxygen isotopic composition of Osilinus turbinatus shells

Oxygen isotope analyses were carried out on the topshell Osilinus turbinatus from archaeological sites with the aim to investigate the temporal exploitation patterns by Mesolithic groups inhabiting coastal caves in SW Italy. In order to assess the present day O. turbinatus intra-annual δ¹⁸O variability, living specimens were collected monthly at Marina di Camerota (SW Italian peninsula). Their shell-edges were analysed and the seasonal results were compared with archaeozoological material. Our findings show that Mesolithic O. turbinatus exploitation was carried out almost exclusively during the colder and intermediary seasons (e.g. autumn, winter, spring), with very sporadic harvesting during the warmer seasons. Results suggest a possible regional exploitation pattern of O. turbinatus by Mesolithic groups inhabiting this region.     

Seasonal Patterns of Coastal Exploitation on the Farasan Islands,Saudi Arabia

Here we present the results of the analysis of coastal exploitation patterns in the southern Red Sea during the Middle Holocene. We focus on the shell midden cluster of the Farasan Islands, Saudi Arabia, which comprises over 3,000 shell midden sites. These sites date from 6,500 to 4,500 cal BP and are part of an arid landscape. We focus on one site, JW1727, which provides a snapshot of marine exploitation and will help to understand the use of food resources within the region. Stable isotope values (δ¹⁸O) were collected from the marine gastropod Conomurex fasciatus (Born 1778), which represents 72% of shell weight of JW1727, in order to reconstruct the season of capture. Results demonstrate that 1) every season is represented within the dataset; and 2) there is increased C. fasciatus deposition during the summer and autumn months. This indicates a diet consisting of C. fasciatus throughout the year in combination with other food sources and an increase of the C. fasciatus component during the arid seasons, possibly linked to the unavailability of vegetation. Additionally, size measurements of C. fasciatus were carried out to examine changes in size distribution throughout the occupation of the site that could be related to overexploitation of C. fasciatus. However, no significant trends could be observed. In sum, the results suggest a sustainable and constant habitation of the Farasan Islands despite the highly arid conditions.     

Geochemical methods for inferring seasonal occupation of an estuarine shellmound: a case study from San Francisco Bay

Seasonal patterns of Native American residence and use of shell mounds of the San Francisco Bay area, California are of great interest. This work investigates seasonal occupation by means of a new method for interpretation of geochemical data from Mytilus trossulus specimens recovered from one of these structures, the Ellis Landing Shell Mound (CA-CCO-295). The approach, which is suitable for relatively small shell fragments from a variety of archaeological contexts, is used to infer the environmental conditions (temperature and salinity of ambient water) at harvest time, compared with average conditions for the period, and thus estimate the season during which the shells were harvested. This information, in turn, is employed to evaluate current models about the growth and construction of prehistoric shell mounds in San Francisco Bay. The method was applied to seven different lenses in the shell mound ranging in age from ∼240 cal yr BP to ∼3510 cal yr BP. We found that, although seasonal occupation varied over time, it generally was confined to summer through late fall, with little indication of winter gathering. Our findings suggest that California shell mounds, such as Ellis Landing, were constructed in a very different manner than some other mounded places used by contemporaneous hunter-gatherers elsewhere in North America.     

Kana Tamata or Feasts of Men: An Interdisciplinary Approach for Identifying Cannibalism in Prehistoric Fiji

By integrating osteological, taphonomic, archaeological and stable isotopic data, we test for cannibalism in the Lau Group, Fiji and discuss the potential underlying cause(s) and context(s) of this behaviour. First, we compare taphonomic and element representations of human skeletal material from two contexts in Fiji, examining human bone fragments from archaeological sites, including middens and burials in the Lau Island Group. Fourteen sites produced human remains. Only two of those sites included distinct human burial contexts, but in the remaining 12 sites, the human bone was recovered from middens or contexts where midden was mixed with possible secondary burials. A total of 262 number of identified specimens per species, representing an estimated 15 minimum number of individuals make up the Lau human assemblage. Second, we analysed bones contained in 20 individual human burials from four different sites that are housed at the Fiji Museum for comparative purposes. Third, we examine previously published stable isotopic (δ¹³C, δ¹⁵N) analysis of bone collagen to gauge protein consumption of likely cannibalised humans in midden contexts and potential cannibals from primary burials. We model a cannibalistic diet category within the context of isotopically measured Pacific Islands food groups and apply an isotopic mixing model to gauge plausible dietary contributions from six sources including human flesh. Isotopic mixing models of the Lauan samples illustrate a high diversity in reconstructed diets. The percent contribution of human flesh is low for all individual Lauans. We conclude that mortuary rituals evidenced by sharp‐force trauma may suggest non‐nutritive and non‐violent practices that may have included the consumption of small amounts of human flesh. Copyright © 2012 John Wiley & Sons, Ltd.     

Oxygen isotopes in cellulose identify source water for archaeological maize in the American Southwest

Maize (Zea mays) was a primary food crop for aboriginal societies of the arid American Southwest. Water used for maize production in these arid zones could have come from precipitation and runoff during the summer monsoon, from perennial streams and springs, or from stored soil water fed by snowmelt. The oxygen stable isotope ratio (δ¹⁸O) of summer and winter precipitation on the Colorado Plateau naturally differ by more than 10‰ providing a powerful tool for distinguishing winter- from summer-derived water sources used in cultivation of maize. We investigated whether variation in δ¹⁸O of potential source waters is preserved in the δ¹⁸O of cellulose (δ¹⁸O_cellulose) of maize cobs by growing four aboriginal and one modern maize variety in pots irrigated with water of known δ¹⁸O composition. The δ¹⁸O_cellulose values of cobs ranged from 26.8 to 36.4‰ (averaged within varieties) and were highly correlated with δ¹⁸O values of the source irrigation water (−15.8 to −8.2‰). Cob δ¹⁸O_cellulose from five archaeological sites on the Colorado Plateau in southeastern Utah ranged from 27.3 to 34.6‰, closely matching the range of values observed in experimental plants. A δ¹⁸O_cellulose model developed originally for tree rings was parameterized and applied to the archaeological maize cobs. The model indicated that monsoonal precipitation accounted for 0–20% of the moisture for archaeological cob samples from a site adjacent to a perennial stream and 43–98% for samples from an upland site, more distant from a perennial water source. These results reveal the potential for using δ¹⁸O_cellulose to investigate prehistoric irrigation practices and source water used for maize production in the American Southwest.     

Oxygen isotope seasonality in a temperate estuarine shell midden: a case study from CA-ALA-17 on the San Francisco Bay,California

Seasonality determination using stable oxygen isotope (δ¹⁸O) analyses in archaeological mollusk shell has been largely limited to aquatic settings where one of the two factors that control shell δ¹⁸O – water δ¹⁸O (or salinity) and temperature – is assumed to be constant. Open coastal marine environments reflect the former situation, and tropical estuaries constitute the latter. In an effort to expand stable isotope seasonality to an ecological setting where neither variable remains constant, we present a model of annual shell δ¹⁸O cycle of aragonite deposition derived from instrumental data on salinity and temperature from San Francisco Bay, California. The predicted range of modeled shell δ¹⁸O is consistent with observed δ¹⁸O values in prehistoric and modern shells when local conditions are considered. Measurements of δ¹⁸O taken at 0 mm and 2 mm from the terminal growth margin were made on 36 archaeological specimens of Macoma nasuta from a late Holocene hunter-gatherer site CA-ALA-17, and season of collection was inferred using the shell δ¹⁸O model. We conclude that shellfish exploitation occurred through the year with the exception of fall, which may indicate scheduling conflicts with acorn harvesting or other seasonally abundant resources elsewhere. The model supports the feasibility of stable isotope seasonality studies in temperate estuaries, provided that instrumental records are available to quantify the relevant water conditions at appropriate spatial and temporal scales.     

Stable Carbon and Oxygen Isotope Spacing Between Bone and Tooth Collagen and Hydroxyapatite in Human Archaeological Remains

Spacing between stable isotope values in bones and teeth is a valuable tool for examining dietary influences and diagenesis. This study examines carbon and oxygen isotope values from collagen and hydroxyapatite (structural carbonate and phosphate) in archaeological human bones and teeth to derive species‐specific correlation equations and isotope spacing values. The δ¹³C_collagen and δ¹³C_{structural carbonate} in bone and dentin collagen show a strong correlation (R = 0.87, 0.90, respectively) with an average Δ¹³C_carb‐coll spacing of 5.4‰. The consistency of this isotope spacing with other large mammals and in humans with both low and high protein intake (as indicated by enriched δ¹⁵N values) suggests a similar allocation of protein‐derived carbon and whole diet‐derived carbon to collagen and structural carbonates, respectively, as other terrestrial mammals regardless of absolute meat intake. The δ¹⁸O_{structural carbonate} and δ¹⁸O_phosphate show the strongest correlation in enamel (R = 0.65), weaker correlations in dentin (R = 0.59) and bone (R = 0.35), with an average Δ¹⁸O_carb‐phos of 7.8‰. This isotope spacing is slightly lower than previously reported for large mammals and limited available data for humans. The results potentially indicate species‐specific fractionations and differing access to body water and blood‐dissolved inorganic carbonates in the presence of collagen formation. The use of correlation between δ¹⁸O_{structural carbonate} and δ¹⁸O_phosphate to determine diagenetic state is not recommended. The strength of this correlation observed in bones and teeth is variable and alternate indicators of diagenetic state (i.e. C:N ratios of collagen) provide more robust and independent evidence of isotope preservation despite presence/absence of a strong isotope correlation. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.     

Nitrogen cycling in western India as revealed by nitrogen isotopes,and the historic production of saltpetre

Saltpetre (KNO₃) manufacture was a principal monopoly industry in early Modern India when the United Kingdom governed the social and economic systems. The process represented microbial transformation of excrementitious livestock and human wastes deposited around habitats, resulting in formation of salt efflorescence at an economic scale. Low caste people collected these wastes for extraction and production of rough saltpetre under the administrative control of British India. Stable isotope composition (δ¹⁵N and δ¹⁸O) was used to trace details of the microbial transformation processes, often involving the isotopic fractionation of nitrogen and oxygen. Marked elevation in δ¹⁵N and δ¹⁸O values for nitrates in soils and deposits, relative to those of primary organic nitrogen in diets and water sources, characterizes the unique processes of historic saltpetre manufacture in British India.     

CONFIRMATION OF AN ARCHAIC PERIOD MOUND IN SOUTHWEST MISSISSIPPI

Abstract

Site 22LI504 is a predominantly Archaic period site in Lincoln County, Mississippi. One of its primary elements of interest is a single conical mound from which small-diameter cores revealed evidence of advanced pedogenesis. A radiocarbon sample from one soil core produced a date suggesting that the mound was Archaic in age (Fulmer 2001); however, it was unclear whether the sample came from within the mound or an underlying midden. In the spring of 2006, we excavated a 1-x-1-m unit in the mound to investigate this question. Diagnostic lithic artifacts, an advanced state of soil horizonation, and a lack of ceramics indicate that the mound is of Archaic period construction, with as many as five construction stages and artifact-rich features. We describe the soil profiles, features, and artifacts recovered from the mound, with comparisons to excavation units in an adjacent Archaic midden to show that there is no clear evidence for the mound being a functionally specific locus. We also present radiocarbon dates that indicate the earthwork is over 5,000 years old. These results are evaluated within the broader context of Archaic mound building, focusing in particular on environmental parameters underlying bet-hedging behavior.     

MARINE RESOURCES IN THE MESOLITHIC AND NEOLITHIC AT THE GROTTA DELL’UZZO (SICILY): EVIDENCE FROM ISOTOPE ANALYSES OF MARINE SHELLS*

Oxygen isotopes in shell carbonate samples from the marine rocky‐shore intertidal gastropod Monodonta turbinata (Born) are investigated in both modern analogue specimens and in archaeological specimens from the Grotta dell’Uzzo (Sicily). Variations in shell edge values of δ¹⁸O in living specimens collected monthly over two years are closely correlated with monthly seawater temperatures measured at the time of collection, showing that the species can be used for palaeoseasonality studies. Analyses of shell edge δ¹⁸O values in archaeological specimens, from Mesolithic through to early Neolithic phases at the Grotta dell’Uzzo, enabled the inference of various seasons of collection of shellfish and how such seasonality varies between the different phases of occupation. Interesting similarities and differences exist between the seasons of marine shellfish exploitation and the seasons inferred from the vertebrate zooarchaeological assemblages. A major inference drawn from the analyses and discussion is that the exploitation of all marine resources (fish and shellfish) increased in the later Mesolithic and early Neolithic periods.     

C4‐Plant Foraging in Northern Italy: Stable Isotopes,Sr/Ca and Ba/Ca Data of Human Osteological Samples from Roccapelago (16th–18th Centuries AD)

Human osteological samples (n = 23) taken from different anatomical parts of 11 individuals from the early modern (16th–18th century AD) site of Roccapelago (Modena, Italy) were systematically analysed for δ¹³C, δ¹⁵N and trace elements to investigate their diet. δ¹³C and δ¹⁵N correlate and show a high variability between individuals, attesting to the dietary contribution of C₄ plants. This is supported by pollen analysis of the burial site samples, which revealed the presence of maize. δ¹⁵N correlates with Sr/Ca, suggesting that the main protein source could have been milk and dairy. We therefore interpret the strong correlation between δ¹³C and δ¹⁵N as evidence for C₄‐plant foraging practice and the exploitation of livestock for meat and milk, combined with possible direct intake of C₄ plants. The Roccapelago site represents an important case study to track the evolution of the post‐medieval diet and the introduction of maize cultivation in southern Europe, as also attested by historical sources.     

Radiocarbon Marine Reservoir Effect in Human Remains from the Kitakogane Site,Hokkaido, Japan

Accelerator mass spectrometry (AMS) was used to measure radiocarbon (¹⁴C) in bones excavated from the Late Jomon shell midden at the Kitakogane site, Hokkaido, Japan. Comparison between ¹⁴C ages of terrestrial and marine mammals from the same site showed systematic age differences which could be attributed to the ¹⁴C marine reservoir effect in the western North Pacific Ocean. Furthermore, this effect was clearly observed in human remains from this site, indicating a heavy dependence on seafood. Dietary habit was estimated from δ¹³C and δ¹⁵N measured in the same human remains. Apparent ¹⁴C ages indicated 79% of protein originated from marine sources.