ULVS XXII: Crustose Lichen Affecting the Geological Interpretation of Digital Landsat Imagery of the Tripolitanian Pre-desert

Abstract

White surface encrustations developing on basalt which had the same ‘reflectance signature’ on digital Landsat imagery as that from the limestone terrain in the Tripolitanian pre-desert are shown at the Wadi Gobbeen to be the thalli of the crustose lichen of the genus Aspicilia. The reproductive structures and ascospores of the lichen are described. The lichen is seen to be aiding the weathering and disintegration of the basalt cobbles. The absence of the thalli on the sides and underneath of cobbles currently resting upon the present land surface may suggest that soil erosion has been rapid in the recent past.