Archaeological Sites and Slump Risk Inspections

Tom Andrews (NWT Archaeologist’s Permit 2015-021)

Throughout the Northwest Territories, the thawing of ice-rich permafrost is leading to significant landscape disturbance, which is in turn impacting cultural resources. Assessment and monitoring of the extent of impacts to cultural resources from climate change-induced landscape erosion is hampered by the vast and remote geography of the Northwest Territories, yet cultural resource managers are in need of a way to identify areas where the risks to cultural resources from these processes are greatest. In 2015, a team from the PWNHC, GSCI, University of Victoria, and the NWT Geological Survey used archaeological site distribution data, Gwich’in traditional land use data, and retrogressive thaw slump density to create a GIS-based heritage risk assessment for the Gwich’in Settlement Area. Results indicated that the greatest potential risk to Gwich’in cultural resources from thaw slumping occurs along the Peel Plateau, while areas adjacent to the Mackenzie River and Delta appear to be at low risk of impact from this process.

The purpose of this survey was to visually inspect three locations rich in heritage resources to assess whether or not retrogressive slump activity is having a direct impact on archaeological sites. To accomplish this, three target areas were identified. Two of these were located in medium to high risk areas in the eastern flanks of the Richardson Mountains, on the Peel Plateau west of Fort McPherson.  Areas exhibiting medium risk on shores of two lakes on the Ramparts Plateau, east of Inuvik, were also investigated. Each location was visually inspected from a helicopter in August.

On the Peel Plateau we did not identify any archaeological sites that had been directly impacted by slumping. In this region, slumps tend to be located on slopes, extremely large in size, and are continually advancing during the melt season. Consequently, all sites located near slope crests in this area are at significant risk to being impacted by future slump activity. In the Ramparts Plateau we found that lake shorelines were experiencing significant erosion but at a scale such that they were not visible in our earlier satellite mapping research. Consequently, areas defined as low or medium risk may incorrectly define actual risk due to the scale of the erosion. In the future, a nested approach should be used, including the broad-scale techniques used in our study coupled with change detection, fine-scale mapping, and, where possible, low-level airborne inspections.

(Edited by Shelley Crouch, Prince of Wales Northern Heritage Centre)