Using satellite image analysis for locating prehistoric archaeological sites in Alaska's Central Brooks Range

Abstract

In this pilot study, we apply satellite image analysis to archaeological site prospection in Alaska's Brooks Range. Our goal was to test whether satellite remote sensing, which has been successful in locating large archaeological features associated with sedentary peoples, could be applied to arctic interior sites associated with mobile hunter–gatherers. In particular, we strove to develop a relatively straightforward and inexpensive model using existing data which could be used to help guide archaeology surveys. Using 1-m resolution IKONOS imagery of Lake Matcharak along the upper Noatak River, we produced a Normalized Difference Vegetation Index (NDVI) and tasseled cap transformation of the study area and stacked these five vegetation indices into one image. We then applied unsupervised and supervised classifications to the image first, to test for the presence of a site-specific spectral class and second, determine the nature of that class. Through a visual analysis of the unsupervised classification, a spectral phenomenon was seen to co-occur with archaeological sites in the study area. The supervised classification provided a high-resolution land cover map used to identify the signature as the ecotone between un-vegetated sediments and dense willow (Salix sp.) stands. Dense willow stands along the Lake Matcharak shore visually correlate with most of the known archaeological sites, possibly reflecting landform and/or vegetation characteristics that would have appealed to past inhabitants. The methods described here could contribute to building better survey strategies and archaeological predictive models for elsewhere in the Brooks Range and Alaska.