This thesis is about the interpretation of the depositional environment of Adigrat sandstone from the neglected section of yejube in the Blue Nile sedimentary basin in central northwestern Ethiopia after following a detailed field investigation supported by petrographic and grain size analysis. The data obtained mainly field data that includes color, texture, sedimentary structure, the lateral and vertical continuity of lithology that were investigated. Additionally, the stratigraphic log of the section and geological mapping is conducted. Petrographic and grain size analysis was performed on 27 representative samples. A petrographic analysis result indicates that the studied sandstone is classified mainly as quartz arenite from the modal analysis following point counting of framework grain. The analysis indicating that the sandstone unit is both compositionally and texturally matured. Grain size analysis generally indicates that the sediment consisting of more than one provenance and sediment is deposited not in a restricted environment rather it is deposited in a mixed environment of a fluvial and marine process. Based on the field investigation supported by laboratory result nine lithofacies type has been identified, these are namely Fine-grained Trough cross-laminated sandstone, Medium grained mud crack developed sandstone Facies, Planar cross-bedded medium-grained sandstone facies from lower sub section, Medium grained herringbone cross stratified sandstone facies from the middle part of the section and Well sorted thinly bedded sandstone, Fine-grained hummocky cross stratified sandstone, Fine-grained well-sorted tool marked sandstone, Moderately sorted horizontal bedded sandstone facies, Medium to Coarse grain Bioturbated sandstone facies from lower sub- section. These identified lithofacies type has to be grouped into three facies association to interpret its depositional environment. These facies assemblages are the Meandering river deposit, tidal flats, and continental shelf deposit. The facies stacking pattern indicates that the retrogradational effect of Transgresion process deposits this Formation.