Explanation:

1.   The Indus-Tsangpo Suture Zone (ITZS) defines the areas of collision between the Indian plate and the Kohistan-Ladakh arc in the western Himalayas and the Tibetan Lhasa block in the east. It also marks the zone along which the Tethys Ocean was consumed by subduction processes.

2.  The Tethyan Himalayas are located to the south of the ITSZ. They consist of thick, 10-17km, marine sediments that were deposited on the continental shelf and slope of the Indian continent.

3.   The Higher Himalayas are also known as the Central Crystalline zone, comprised of ductily deformed metamorphic rocks and mark the axis of orogenic uplift. Mica schist, quartzite, paragneiss, migmatite, and leucogranite bodies characterize this uppermost Himalayan zone.

4.  The Main Central Thrust is a major geological fault where the Indian Plate has pushed under the Eurasian Plate along the Himalaya. The fault slopes down to the north and is exposed on the surface in a NW-SE direction.