In the context of the geomorphological evolution of the Eastern Himalayas, the deeply incised transverse gorges cut by rivers such as the Siang and Subansiri through rapidly uplifting mountain blocks are classic examples of which river type?

💡 Solution & Explanation

Rivers like the Siang and Subansiri exhibit antecedent drainage, meaning they established their courses before the rapid tectonic uplift of the Himalayas and maintained their paths by down-cutting at a rate equal to the mountain uplift. Superimposed streams flow on an overlying rock structure that has been eroded to expose an older underlying discordance, which is not the primary mechanism of these major Himalayan gorges. Antecedent river systems provide crucial geological evidence regarding the chronological uplift of the Himalayan mountain belt.