Satellite Remote Sensing of Archaeological Vegetation Signatures in Coastal West Africa

This article discusses how archaeological sites in Sierra Leone, and by extension much of West Africa, can be identified through vegetation patterns (vegetation signatures) detectable in very high-resolution (VHR) multispectral satellite imagery. Settlement sites typically have a differing pattern of vegetation from the surrounding landscape, including concentrations of very large trees with sociocultural and historical significance: cotton (Ceiba pentandra) and baobab (Adansonia digitata). These features are conspicuous elements of the landscape both from the ground and in aerial imagery. Two complementary methods of using VHR multispectral satellite imagery are discussed in this paper: visual interpretation and semi-automated subpixel classification. These techniques are aiding ongoing archaeological survey of the Sierra Leone River Estuary. The impact of recently renewed industrial activity at a site of probable archaeological significance is also assessed through visually interpreted VHR satellite imagery.