Date of Award

Spring 5-11-2018

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Earth Sciences

Advisor

Alice R. Kelley

Second Committee Member

Joseph T. Kelley

Third Committee Member

Daniel F. Belknap

Additional Committee Members

Arthur E. Spiess

Abstract

Shell middens along the Maine coast archive up to 5000 years of cultural and climatic change, but the record is continually and rapidly lost to the sea through climate-driven coastal erosion and sea-level rise. These sites were constructed by the ancestors of Maine Tribes, and are composed of centimeters to meters of clam (Mya arenaria) and/or oyster (Crassostrea virginica) shells, other faunal remains, and cultural materials. Shell middens record human interaction with the environment and early coastal occupation and adaptation. The faunal remains reflect paleoenvironmental conditions and the distribution of extinct and extant forage-species along the western Gulf of Maine. This research utilized ground-penetrating radar as a rapid and cost-effective survey technique for cultural resource management (CRM) decisions. A subset of sites were surveyed to develop a rapid technique for making CRM decisions, but the methodology is applicable to shell middens worldwide.

Traditional methods of shell midden characterization involve expensive, destructive, and labor intensive archaeological excavation. Thus, a limited number of sites have been extensively described. Ground-penetrating radar (GPR) was used to obtain a high-resolution evaluation of vertical and lateral site extent and stratigraphy. Data are collected at a walking pace; thus, the process is rapid and noninvasive if additional ground-truth data are not required. GPR records below surface stratigraphy by noting differences in the electromagnetic properties of the material that reflect variations in layer composition, compaction, grain size, salinity, and/or water content. Of the fifteen sites selected for the study, six sites were surveyed as part of this research. A geographic information system (GIS) comparison of aerial photography time-series at three sites was carried out to determine the applicability of the method to the Maine coastline and attempt to quantify shoreline erosion through time. The historic aerial photo time-series did not provide conclusive results. Structure from Motion (SfM) photogrammetry was carried out on one site within the study, and it serves as a baseline for future high-resolution erosion monitoring through survey time-series comparison.

Also, a stakeholder meeting was held one year into the project. The meeting focused on the need for shell midden monitoring, and it allowed the development of the foundational ideas for a citizen-science monitoring network for shell midden sites along the coast of Maine.

This project demonstrated the applicability of: (1) GPR surveys to delineate and characterize midden extent and stratigraphy in a nondestructive to minimally invasive manner, (2) traditional shoreline change methods to quantify shoreline change at three research sites, and (3) a stakeholder meeting to cooperatively formulate a plan of site evaluation, monitoring, and rescue. Characterizing shell-rich layers and soil horizons and the nature of the underlying material across the site using GPR, using data from prior excavation units, informed a plan for prioritizing areas for future archaeological study. As sea level continues to rise, and sites and the information they hold are currently disappearing, the need for the application of GPR and shoreline change studies of coastal shell midden sites in Maine is critical.

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