Geology of a Part of Tons Valley, Garhwal Himalaya with Special Reference to Old Fold Trends

The Deoban structural belt of the Tons Valley is lithostratigraphically divided into three Groups-the lower Dharagad Group, the middle Deoban Group and the upper Jaunsar and Simla Groups. The contact between the Dharagad and Deoban Groups is an angular unconformity, while the one between Deoban and Sirnlajfaunsar Groups varies from disconformity to paraconformity. The rocks of the Jaunsar Group are thrust over Deoban and Simla Groups along the south hading Tons thrust.

The Sherar syncline, a prominent, NE-SW trending doubly plunging syncline, affecting the Deoban and Simla Groups and truncated by the northwest trending main Himalayan folds is considered a remnant fold of an earlier orogeny.