Peter Leach will undertake an investigation of the response of mid- to late-Holocene people, cultural materials and landscapes to sea-level rise, climate change and ecosystem variability. This will be accomplished through geoarchaeological evaluation of an intertidal mid-to-late Holocene archaeological site on the Gulf of Maine, USA. This precontact, multi-component site was drowned by late Holocene sea-level rise and it is now buried by 1.0-2.0 meters of salt marsh peat. Because the site was submerged, it exhibits exceptional preservation of unburned faunal remains, multi-component stratigraphy, and organic materials. The main goals are to understand the timing and nature site submergence, map the spatial distribution of cultural materials and natural features, and to continue high-resolution unmanned aerial vehicle [UAV] analyses of short-term geomorphic processes. An understanding of preservation potential and the influence of local geographic/geological variables will greatly enhance modeling of site survival through sea-level rise. This will generate information relevant to older sites buried farther offshore. The current project and related future research will provide undergraduate and graduate student training and will generate scientific data ideally suited for public dissemination. Project results will raise awareness of precontact site potential beneath salt marshes, a study area that is frequently overlooked during construction and engineering activities. Project data will benefit Historical Preservation Officers by elucidating the effort required and research potential of intertidal and submerged sites. This in turn should lead to improved regulations regarding environmental impact assessments during wetland remediation or infrastructure improvements. These and other data will demonstrate the need for continuous monitoring and underscore the urgency of identifying archaeological sites threatened by coastal erosion.
In northeastern North America and many other northern hemisphere locations, early- to mid-Holocene coastal sites were submerged through relative sea-level rise and are likely variably preserved due to local geomorphic factors. The investigators seek an understanding of past and on-going geomorphic processes that influence human use of landscapes and long-term preservation potential of submerged and intertidal sites. The researchers will use radiocarbon dating to constrain the age of site components and the timing of sea-level rise. Laboratory techniques will extract and stabilize organic materials unique to waterlogged sites. Traditional archaeological field methods will be augmented by manual core extraction, high-resolution UAV surveys, and intensive spatial data analyses. Site-level inferences will augment geologic models of marine-transgressed landscapes and demonstrate the need for refinement at archaeological scales. UAV mapping is superior to LiDAR and coarse-scale qualitative erosion assessments, and the researchers' innovative use of this technology will generate quantitative data and improve models of short-term (single storm event) erosion and deposition. Though the current project focuses on precontact human and ecosystem responses to sea-level rise and climate change, data generated will help to model the responses of similar systems to future environmental variations.
