Identifying sites of high geoarchaeological potential using aerial LIDAR and GIS on Quadra Island, Canada

Abstract

The dynamic environmental history and relative sea level (RSL) changes experienced on the Northwest Coast of North America during the early post-glacial period and the early Holocene resulted in significant archaeological visibility challenges for prospection of early coastal archaeological sites. This study offers an integrated methodological approach in support of locating palaeo-coastal sites by combining: (1) geomorphic interpretation of landscape attributes captured by LIDAR (Light Detection and Ranging) mapping; (2) GIS-based archaeological site potential mapping; and (3) local RSL history. The RSL history for the study site (Quadra Island, British Columbia, Canada) shows notable regression over the past 14,300 years from a highstand of at least 197 m resulting from post-glacial isostatic rebound. Late Pleistocene and early Holocene palaeo-shorelines are found inland from, and elevated above, modern sea level and represent key areas for archaeological prospecting. Bare-earth Digital Terrain Models (DTMs) derived from the LIDAR dataset were interpreted to identify palaeo-shorelines at 10 m and 30 m above mean sea level. A GIS-derived map was created to identify regions of high archaeological potential. Field validation suggests that this integrated methodology provides a promising approach for archaeological prospection that could be applied to other post-glacial coastal settings.