Explanation:

The Main Central Thrust, marking the boundary between the Lesser and Higher Himalayas, is a zone of more or less parallel thrust planes along which the rocks of the Central Crystallines have moved southwards against, and over the younger sedimentary and metasedimentary (Paleozoic ) rocks.  It is a major tectonic feature, well defined, and easily recognisable in general.  In some places, however, the thrust is not clearly discernible because of a lack of metamorphic or tectonic discontinuity and presence of rocks of similar lithology on either side.