A geological consultant's study of the Glenorchy - Plumbago granitic fault block area in the western half of SML 118, to try to elucidate its relationship to known uranium mineralisation, suggests that there is a structural association of lodes with the regional fracture pattern of faults trending north-east, north-west and east-west. The host rocks, of probably differing ages, are at present classified either as 'adamellite' or as 'regional granites'. In respect of the more U-rich davidite occurrences, some of which lie in metasedimentary sequences containing conglomerates, there is also meagre evidence of stratigraphic control. The igneous (plutonic) and metamorphic history of the study area is more complex than previously realised, with several primary igneous rock types present, of probably widely differing age. However, differentiation of the stratigraphy within the migmatized crystalline basement by careful geological mapping is believed possible. Previous exploration, though extensive, was deficient in the examination of radiometric prospects with weak outcrop manifestations, and little attention was paid to such prospects concealed under cover. Interpretation of newly obtained aeromagnetic data indicates that magnetic patterns can be related to lithology and structure, particularly in the case of these prospects, and such information can be used to assist in the selection of exploration targets. Accordingly, the conduct of further more detailed magnetic surveys and complementary ground exploration is recommended.