The area under study is located within the Mekele outrnlier. It comprises Mesozoic sedimentary rocks unconformablyrnoverlain by trap volcanics.rnLandsat-TM images have been processed and geologicallyrnanalysed in combination with revision of the previous worksrnand present field survey for lithological mapping andrnreconstruction of the stratigraphy of the study area.rnIn remote sensing the sensor and the obj ect to bernsensed are located remotely apart. The link is due tornelectromagnatic (EM) waves. Thus in image processing andrninterpretation the knowledge of how EM radiation isrngenerated, propagated, and modified when it interacts withrnmaterials is the main key.rnMaterials produce a diagnostic spectral signature inrnresponse to the EM interaction. Generally, spectralrnsignatures are related to the nature of the correspondingrnrock, which help to identi fy a material through imagernprocessing. Image processing includes statistical andrngraphical evaluation, ratioing, contrast enhancement,rnprincipal and canonical component analyses, combination ofrnselected bands, texture and vegetation index analyses,rnclassification, and visual interpretation of the images.rnStructures and other lineaments, lithologicalrnboundaries, and drainage patterns are traced directly fromrnthe screen during image interpretation. Ten mappable unitsrnare recognized both by digital image processing and visualrninterpretation. These are from youngest to oldest: Dolorite,rnBasalt, Amba Aradam Formation, Agula Shale, five separatelyrnmappable Antalo Limestone units, and Adigrat Sandstone.rnFrom sedimentary point of view, Adigrat Sandstone isrnfluviatile in origin, while the Antalo Limestone and AgularnShale are related with transgression and regression of thernsea during Jurassic time. Amba Aradam Formation, on therncontrary, lying unconformably on Agula Shale, is probablyrndue to the withdral of the sea caused by an uplift ofrncratonic area related to the separation of America andrnAfrica plates during the Cretaceous time.rnThe final thematic images are geometrically rectifiedrnusing selected ground control points to refer them withrnother maps. Digitally processed images expose fairly wellrnthe main lithologic units with some limitation.