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With an increasing rate of sea level rise inherently linked to climate change, numerous coastal archaeological resources are under threat. In Maine, virtually all 2000+ coastal aboriginal shell middens are eroding. Given limited time and resources, an efficient method for making informed cultural resource management decisions is critical. Herein, we describe a six-step protocol for a minimally invasive and cost-effective ground-penetrating radar delineation of shell midden size and morphology. Benefits of the survey methodology outlined in this study include the efficiency of data collection, the non-destructive aspect of the technique, continuous records of site stratigraphy, and the lower cost as compared to large-scale excavation. Two case studies are presented to illustrate the advantages and challenges associated with this method. [ABSTRACT FROM AUTHOR]

Drowned terrestrial wetland environments, such as lakes, marshes, and beaches, were thought to be rare in formerly glaciated regions like the Gulf of Maine (United States). In the northwestern Gulf of Maine, postglacial relative sea-level changes include a "slowstand" between 11.5 ka and 7.5 ka, when the ocean rose <5 m. This period of sea-level stability permitted erosion of glacial materials and concomitant construction of spits and sheltered wetland habitats, attractive to human occupation, between 17 m and 22 m below modern sea level. This work underscores the importance of a well-constructed sea-level chronology to predict the location of drowned terrestrial environments and associated cultural resources. [ABSTRACT FROM AUTHOR]

Ireland experienced a spatially complex pattern of relative sea-level (RSL) changes and shoreline development caused by the interplay of isostatic and eustatic (ice equivalent sea level) processes since the Last Glacial Maximum (LGM). Using a combination of high-resolution marine geophysical data, vibrocores, foraminiferal analysis and 10 AMS radiocarbon dates, we reconstruct the Late Quaternary evolution and RSL history of Bantry Bay, a large (40 km long, 5–10 km wide) embayment in SW Ireland. The data indicate two infill phases: one before and one after the LGM, separated by glacial and lowstand sediments. The pre-LGM history is not dated and the depositional history is inferred. A large sediment lobe formed at the outer edge of Bantry Bay as a lowstand ice-proximal glacimarine outwash system as the ice retreated after the LGM, at a sea level ca. 80 m lower than present. Iceberg scour immediately west of this location likely relate to the break-up of the local Kerry–Cork Ice Cap. Long curvilinear ridges, seen both offshore and on top of the sediment lobe, probably formed as shoreface ridges under stronger-than-present tidal currents during a period of RSL stability (pre-14.6 ka cal BP). A subsequent infill phase is characterised by a basin-wide erosional (ravinement) surface and the deposition of inter- and sub-tidal estuarine sediments. Although our data support the general trends, our stratigraphic and radiocarbon data suggest a higher sea level between 11 and 13.5 ka cal BP than predicted by existing glacial isostatic adjustment models. [ABSTRACT FROM AUTHOR]

Abstract: Sources of sedimentary organic matter to a Morse River, Maine (USA) salt marsh over the last 3390±60RCYBP (Radiocarbon Years Before Present) are determined using distribution patterns of n-alkanes, bulk carbon isotopic analysis, and compound-specific carbon isotopic analysis. Marsh foraminiferal counts suggest a ubiquitous presence of high marsh and higher-high marsh deposits (dominated by Trochammina macrescens forma macrescens, Trochammina comprimata, and Trochammina inflata), implying deposition from ∼0.2m to 0.5m above mean high water. Distributions of n-alkanes show a primary contribution from higher plants, confirmed by an average chain length value of 27.5 for the core sediments, and carbon preference index values all >3. Many sample depths are dominated by the C25 alkane. Salicornia depressa and Ruppia maritima have similar n-alkane distributions to many of the salt marsh sediments, and we suggest that one or both of these plants is either an important source to the biomass of the marsh through time, or that another unidentified higher plant source is contributing heavily to the sediment pool. Bacterial degradation or algal inputs to the marsh sediments appear to be minor. Compound-specific carbon isotopic analyses of the C27 alkane are on average 7.2‰ depleted relative to bulk values, but the two records are strongly correlated (R 2 =0.89), suggesting that marsh plants dominate the bulk carbon isotopic signal. Our study underscores the importance of using caution when applying mixing models of plant species to salt marsh sediments, especially when relatively few plants are included in the model. [Copyright &y& Elsevier]