Geomorphologic Development Across the Active Main Boundary Thrust, An Example from the Nainital Hills in Kumaun Himalaya

Abstract

The Main Boundary Thrust marking the tectonic junction between the Lesser Himalaya and Siwalik molasse represents a zone along which underthrusting still occurs. Depositional terraces formed as a consequence of subrecent and historical landslides have been faulted and displaced vertically as well as horizontally in the Balia Valley, which follows the zone of the Main Boundary Thrust. Vertical scarps and triangular facets on the hillsides, uplift and dissection by faults of terraces and landslide fans, and presence of abandoned valleys across the Main Boundary Thrust, further bear testimony to recent movements. The burden of evidence points to uplift of the Siwalik domain by 30 to 80m relative to the Lesser Himalayan belt.