North-west part of the Indian peninsula was converted into a great centre of vulcanicity in
- A.the end of Cretaceous period
- B.the mid of Cretaceous period
- C.the start of Cretaceous period
- D.the whole of Cretaceous period
Correct answer
Explanation
The correct answer is A, the end of Cretaceous period. The Deccan Traps, the vast lava plateau of the north-western peninsula, were laid down by eruptions at the close of the Cretaceous, about 66 million years ago.
As the Indian plate drifted north over the Reunion hotspot, basaltic lava poured out of long fissures in flow after flow, not from cone-shaped volcanoes. The flows built a step-like plateau covering most of Maharashtra and parts of Gujarat, Madhya Pradesh and Karnataka, more than 2,000 metres thick near Mumbai. Weathering of this basalt gave the black cotton soil (regur). The eruptions are also linked with the mass extinction that ended the age of dinosaurs.
B is wrong: the middle Cretaceous saw no such outpouring in the peninsula.
C is wrong: the early Cretaceous predates the Deccan eruptions by tens of millions of years.
D is wrong: the main eruptions lasted under a million years near the end of the period, not through its whole length of about 80 million years.
Exam tip: Deccan Traps = fissure basalt at the Cretaceous-Tertiary boundary, the parent of black soil.
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3. Agartala
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