Given below are two statements, one is labelled as Assertion (A) and the other as Reason (R).
Assertion (A) : The Himalayas are still rising.
Reason (R) : The Indian tectonic plate is colliding with t

Question

Given below are two statements, one is labelled as Assertion (A) and the other as Reason (R).
Assertion (A) : The Himalayas are still rising.
Reason (R) : The Indian tectonic plate is colliding with the Eurasian plate.
Select the correct answer from the codes given below :

UnlockIAS · Accepted Answer

Correct — C, Both (A) and (R) are true and (R) is the correct explanation of (A). The Assertion is true: the Himalaya is a live, growing range, not a finished one. Satellite geodesy (GPS stations across the arc) records the range being pushed up by a few millimetres a year, the rivers are still cutting gorges faster than the slopes can grade themselves, and the whole belt is India's most earthquake-prone zone precisely because rock is still being shortened there. The Reason is also true, and it is the mechanism, not a coincidence: the Indian plate broke away from Gondwana, drifted north across the Tethys, and began colliding with the Eurasian plate roughly 50 million years ago; India is still driving northward at about 5 cm a year, and a part of that convergence is taken up as crustal shortening and thickening in the Himalaya. Because two continental blocks are of similar low density, neither can be subducted cleanly — so the convergence is absorbed by folding, thrusting and thickening, and thickened crust rises isostatically. Uplift is therefore the direct consequence of collision, which is exactly what (R) being 'the correct explanation of (A)' means.

Why the other options are wrong — (a) Both statements are indeed true, but this option denies the causal link, and the causal link is the whole point. There is no other agent lifting the Himalaya — the uplift is the surface expression of continued India–Eurasia convergence, the same convergence that drives the range's earthquakes.  (b) The Assertion is not false. Every standard indicator of a young, actively rising range is present in the Himalaya — deep gorges, abrupt U-turn river courses, steep landslide-prone slopes, several parallel ranges, and a measurable modern uplift rate. Erosion removes a great deal of that uplift, but the range has not stopped growing.  (d) The Reason is not false either. The India–Eurasia collision is one of the best-documented facts in plate tectonics: the suture is traced along the Indus–Tsangpo zone, marine sediments of the vanished Tethys now sit thousands of metres above sea level, and modern GPS measurements show the two plates still converging at roughly 5 cm a year.

Concept: The Himalaya is a collision (continent–continent) orogen. About 140 million years ago the Indian plate rifted from Gondwana and drifted north, consuming the floor of the Tethys Sea ahead of it. When the Indian continental block finally met the Eurasian block — the collision is conventionally dated to about 50 million years ago — neither could sink, because continental crust is too buoyant to subduct. The convergence has since been absorbed by folding and by slip on a stack of great north-dipping thrusts, which thickens the crust and pushes the surface up. That process is still running, so the Himalaya is still rising.

State PCS 2024 Q32 — Geography PYQ with Answer

State PCS 2024 Q32 — Geography PYQ with Answer