Neotectonics

The collision between the Indian subcontinent and the Eurasian continent, which started in Paleogene time and continues today, produced the Himalaya and the Tibetan Plateau, a spectacular modern example of the effects of plate tectonics. Nepal lies completely within this collision zone, occupying the central sector of the Himalayan arc, nearly one third of the 2,400 km (1,500 mi)-long Himalayas.
The Indian plate continues to move north relative to Asia at the rate of approximately 50 mm (2.0 in) per year. Given the great magnitudes of the blocks of the Earth's crust involved, this is remarkably fast, about twice the speed at which human fingernails grow. As the strong Indian continental crust subducts beneath the relatively weak Tibetan crust, it pushes up the Himalayan mountains. This collision zone has accommodated huge amounts of crustal shortening as the rock sequences slide one over another.
Erosion of the Himalayas is a very important source of sediment, which flows via several great rivers (the Indus to the Indian Ocean, and the Ganges and Brahmaputra river system) to the Bay of Bengal.