Geology of the Tosham area, Haryana

The rocks exposed in and around Tusham hill belong to the Malani igneous suite of rocks and have been dated at 732 Ma. The main Tusham hill consists of a quartz porphyry ring dyke, felsite, welded tuff and muscovite biotite granite. The country rocks are quartzite with chiastolite belonging to the Delhi Supergroup. C. A. Mcmahon was the first British geologist to study these rocks. He described the petrography of the rocks in 1884 and 1886 and published his work in the Records of Geological Survey of India. The other neighbouring hills such as Khanak, Riwasa, Dulehri, Dadam etc. are composed of granite porphyries. The main Tusham hill is an extinct volcano which erupted sometime 732 Ma BP. The Tusham rocks are the source of primary tim in the country, but found to be not viable commercially. The granites and Granite porphyries are high heat producing type. They have high abundance of U.TH and K. Highest heat flow in India is recorded from this area.