Geography · Ch 2 — Structure and Physiography
The Himalayas and Other Peninsular Mountains
The Himalayas and Other Peninsular Mountains
The photograph shows a river in its youthful stage, cutting a deep, narrow channel through solid rock. The walls of the valley rise almost vertically on both sides, leaving barely enough room for the stream itself at the bottom. The water is fast-moving and turbulent, filling the entire floor of the cut. There is no floodplain, no wide valley floor, and no visible sediment terraces — the river is spending all its energy on downward erosion, not on widening its course.
This is a gorge, and the image makes the defining feature unmistakable: the valley is far deeper than it is wide, with steep, often cliff-like sides. The fast-flowing water at the bottom is not incidental — it is the cause of the shape. In the youthful stage of a river, the gradient is steep and the discharge is concentrated, so the stream cuts vertically into the bedrock. Over time, this downcutting produces a V-shaped cross-section, and when the rock is hard and resistant, the sides stay steep and the notch becomes a gorge. …
The Himalayas, geologically young and tectonically active, form the northernmost boundary of India, stretching in a continuous arc from the Indus to the Brahmaputra. In contrast, the Peninsular mountains—the Aravalli, Vindhya, Satpura, Western Ghats, and Eastern Ghats—are much older, eroded remnants of ancient plateaus, with their own distinct origins and structural alignments. Together, these two mountain systems define the fundamental physiographic contrast of the subcontinent: the towe …