Granitic Gneisses of Lansdowne (District Pauri-Garhwal, U.P.)

The granitic gneisses of Lansdowne area form a part of the Amri unit of Garhwal nappe, formed before the main Himalayan orogeny. Field and petrological observations indicate that they have been thrust along with the crystalline rocks of Amri unit and there is no separate thrust contact between them. Chemical analysis and Petrography of the samples of gneisses from the margin to the centre show a progressive increase in feldspar-content which suggests a metasomatic origin for these granitic gneisses.