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Geomorphology / Mountains — UPSC Mains Model Answer

Geography · UPSC CSE
Question: Classification and geographical distribution of mountain types — fold mountains, block mountains, and residual mountains with reference to global and Indian examples

Introduction

Mountains are classified by their mode of origin — folding, faulting, volcanism, or erosion. Understanding this classification is essential for interpreting tectonic history, resource distribution, and regional geography across continents.

Body

1. Western Ghats as Fault Escarpments

The Western Ghats are not fold mountains but are broadly understood as escarpments formed along a rifted continental margin, associated with the breakup of Gondwanaland. Their steep western face and gentle eastern slope reflect structural faulting rather than compressional folding, lending validity to their classification as block mountains or horst-like features.

2. Atlas Mountains — Young Fold Mountains

The Atlas Mountains of North Africa were formed during the Alpine-Himalayan Orogeny, the same tectonic episode that produced the Alps and Himalayas. They are correctly classified as young fold mountains, exhibiting folded sedimentary strata and ongoing seismic activity consistent with relatively recent orogenic processes.

3. Scandinavian Mountains — Ancient Orogeny, Not Residual

The Scandes are remnants of the Caledonian Orogeny, making them ancient fold mountains that have been heavily eroded over geological time. While erosion has reduced their height, they are more accurately classified as ancient or relict fold mountains rather than residual mountains in the strict geomorphological sense.

4. Eastern vs. Western Ghats — Slope Asymmetry

Contrary to Statement 4, the Western Ghats are steeper than the Eastern Ghats. The Western Ghats rise abruptly from the narrow Konkan coast, while the Eastern Ghats are discontinuous, lower, and have gentler gradients, having been dissected by eastward-flowing peninsular rivers over millions of years.

Conclusion

Accurate classification of mountains requires distinguishing between origin, structure, and subsequent erosional history. Statements 1 and 2 are broadly correct; Statements 3 and 4 reflect common misconceptions that conflate erosional age with residual classification and misread Ghat asymmetry.

Word count: 255

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