Developments in the geological exploration of Nepal

Prior to 1950, only sporadic geological observations by a few visitors were made in Nepal. With the opening of the country to foreigners in 1950, Nepal soon came into the focus of interest in Himalayan geology. It was the time of the classical "descriptive geology" with mapping as the primary objective. Several excellent monographs and the first geological maps of different parts of the Nepal Himalaya were produced. The best results were obtained in the richly fossiliferous "Tibetan" sedimentary zone in the north, whereas descriptions of the Central Crystalline zone and of the thick, unfossiliferous metasediments of the Lesser Himalaya reflected mainly the widely differing interpretations and conflicting views of the investigators; nappe structure vs. block tectonics was the main issue. .. With the advent of plate tectonics in the late 1960s, the Himalaya became the "collided range". Microstructural, mineralogical and geochemical studies in the search for stress and heat effects of subduction and collision on structure, metamorphism and magmatism became dominant and in Nepal concentrated on the Main Central Thrust, which was treated in terms of post­ collisional continental subduction. With it went a shift of emphasis from field to laboratory work, from observation to interpretation, from mapping to modelling, from fact to theory. The last thirty years were characterised by the strengthening and diversification of geological institutions in Nepal with the creation of a National Seismological Centre, the beginning of petroleum exploration in the southern foreland of the Himalaya, an intensification and modernisation of classical geological surveying and a strong engagement in the application of geology for engineering and natural hazard assessment purposes.