Karnataka
Chitradurga - The study area is were the history of the oldest rocks of India unfolds. The region is part of the Western Dharwar craton. During the field, we travelled from older to younger successions. For understanding the geological evolution of the rocks in the region, we travelled through three different traverses (across the strike of the formations) Along the traverses the first group of rocks belonged to the Sargur group, which comprised of mafic rocks that show petrological variations from normal amphibolites to hornblende-rich and diopsidic amphibolites (garnet-rich and garnet-poor varieties). Following this is the Chitradurga group of rocks. Chitradurga group starts with the polymict Talya Conglomerate associated with siliceous schists (quarts-sericite – chlorite schists) that mark the transitional contact with Bababudan Group. Two major lithic packages constitute Chitradurga Group, the lower Vanivilas Subgroup and upper Ranibennur Subgroup. Vanivilas Subgroup consists of quartz arenite, phyllite, limestone/dolomite, manganese formations and BIF. Vanivilas subgroup is conformably overlain by the Ranibennur subgroup consisting of fine grained greywackes at the basin margin as well as in the deeper part of the basin. Outcrops of younger granites and contact zones between the younger granites and older basalts were also studied in the field.
Mardihalli Pillow lavas national geo-monument (National Geological Monuments of India by the Geological Survey of India (GSI)) at Mardihalli village near Hiriyur was also visted. The pillow lavas found in this place are about 2200 million years old. They were formed by the sudden cooling of basaltic lava in the ocean floor and form pillow like structure.