The Brahmaputra
Explanation
The Himalayas are a series of parallel mountain ranges extending in a west-east direction. Geographically, the longitudinal extent of this mountain system is defined by major river gorges at its western and eastern extremities.
Detailed Analysis
- The Brahmaputra: This river marks the eastern-most boundary of the Himalayas. The mountain range runs in an east-west direction from the Indus gorge in the west to the Brahmaputra gorge in the east.
- The Dihang Gorge: The Brahmaputra (known as the Dihang or Siang in Arunachal Pradesh) cuts through the Himalayas near Namcha Barwa. Beyond this deep gorge, the Himalayas bend sharply to the south and spread along the eastern boundary of India, forming the Purvanchal (Eastern Hills). While the gorge is the specific physical feature, the boundary is attributed to the river system.
- The Teesta: This river flows through Sikkim and West Bengal and is a tributary of the Brahmaputra. It is located within the central-eastern section of the Himalayas, not at the eastern terminus.
- The Lohit: This is a tributary of the Brahmaputra that flows through Arunachal Pradesh and Assam. It originates in eastern Tibet but does not define the primary geological boundary of the main Himalayan range.
Key Takeaway
The Himalayas extend over a distance of about 2,400 km, bounded by the Indus river in the west and the Brahmaputra river in the east.