Multitemporal study of obsidian exploitation from Melka Kunture (Ethiopia) through digital photogrammetry and multispectral stereo-IKONOS II

Obsidian exploitation represents a leitmotiv of the Melka Kunture sequence during the last 1.7 Myr and the first exampIe of Oldowan exploitation of this raw material. The primary nearest obsidian source, Balchit, 7 km north from Melka Kunture, is a domo-flow dated to 4.37 ± 0.07 Myr and visible at the surface thanks to wide areas of dispersion and outcrops. The proximity of primary and secondary BaIchit obsidian sources, a high quality of raw material easi1y available in large quantity, represents an unique situation of the Oldowan and Acheulian East African sites, one of the few African geographical areas with high obsidian sources. In order to evaluate the human impact on the multitemparal change detection of obsidian outcrops from aerial photos and IKONOS II imageries, respectively dated al !he 1972 and 2006, the land use interpretation following the CORINE land cover Nomenclature have been produced. The precise localization and the measure of their superficial extension have been possible due to the utilization of aerial photos and of couples of recent satellite stereoscopic IKONOS II imageries at a high spatial resolution (1 m). These last have been also utilized for the creation of the new topographic map of the area (l00km2) at a scale of 1: 10,000 and of the Digital Elevation Model. The images, geometrically corrected and oriented thanks to Ground Control Points measured in site through a DGPS survey, have been radiometrically and spectrally corrected in order to permit the recognition of obsidian accumulation, in respect with ground truths collected during fieldworks. The' individuation of the obsidian outcrops and dispersion areas, has been done thanks to the high spatial resolution and the multispectral character of the satellite imageries. Image spectral and spatial enhancements have been applied to the scenes, while automatic classification of multispectral orthoikonos have been aided by spectral analysis carried out on obsidian samples by the FieldSpecPro spectroradiometer, ranging in the 0.4-2.5 11m electromagnetic interval.