Assessing the Scale and Pace of Large Shell-Bearing Site Occupation in the Prince Rupert Harbour Area, British Columbia

ABSTRACT

Methodological advancements in geoarchaeology and spatial and chronological modeling are opening new avenues to interpreting large coastal shell-bearing sites. We document the developmental histories of two such sites around Prince Rupert Harbour, Canada, using systematic percussion coring, intensive radiocarbon dating, and 3D surface mapping with Total Station and LiDAR. We also re-analyze a third site (Boardwalk/GbTo-31) excavated and radiocarbon dated in the 1960s, 1970s, and early 2000s using archival field notes, site maps, and stratigraphic profiles georectified using LiDAR. We map the natural landform beneath the sites and document the degree to which people physically modified landforms through the deposition of massive shell accumulations. We model site development through time and space and use accumulation rates and OxCal modeling to test for intentional deposition events. All three sites demonstrate complex and heterogeneous occupation histories. At each we identify instances of very rapid deposition that effectively terraced and extended parts of the natural landform to create places for constructing houses, though these episodes take place within longer histories of slower quotidian deposition. The anthropogenic modifications to the coastline in this area are the result of these mixed processes associated with long histories of occupation.

Keywords:

• Northwest Coast Archaeology
• shell middens
• shell-bearing sites
• accumulation rates
• anthropogenic landscapes
• percussion coring
• 3D mapping

ACKNOWLEDGEMENTS

We gratefully acknowledge the Lax Kw'alaams and Metlakatla Indian Bands for supporting our research. We especially thank Steven Dennis, David Leask, Dave Doolan, Paul Ewonus, and Corey Cookson for help in the field. We thank all previous excavators from the North Coast Prehistory Project for their pioneering work, and Gary Coupland for providing additional information on his excavations at Boardwalk. We also thank the three anonymous reviewers for their constructive comments. We are grateful to Nexen Ltd. for providing the LiDAR DTM for the study area and to Metlakatla Indian Band for logistical support in the field. This project was generously funded by SSHRC (Grant # 410-2011-0414), NSF (Grant # 1216847), and the Canadian Museum of History

Notes

1. In a past study on the Dundas Islands (Martindale et al. 2009) we applied a constant expansion factor to humic material based on experimental calculations; however, we found that humic material compressed to very different degrees at different sites in the Prince Rupert area, so we opted not to apply differential expansion factors to different strata in this study. Further experimental work is required to assess if we can determine specific expansion factors for specific sediment types.

2. We use calibrated medians because the calculations require single ages, though we recognize that medians of calibrated radiocarbon probability ranges do not necessarily represent the age with the highest probability within the range.

3. All individual excavation units at GbTo-31 are labelled in Supplemental Figure 2.