The Deccan Trap of peninsular India was formed by
- A.fissure eruptions of basaltic lava
- B.deposition of sediment in a shallow sea
- C.metamorphism of ancient gneisses
- D.explosive eruptions of a single central volcano
Correct answer
Explanation
The correct answer is A, fissure eruptions of basaltic lava. At the close of the Cretaceous, highly fluid lava welled out of long cracks in the crust in the north-western Deccan and spread as sheet after sheet over Maharashtra and parts of Gujarat and Madhya Pradesh; the flat, step-like arrangement of these flows is what the word trap describes. Option B is wrong because sedimentary deposition in a shallow sea produced the Cuddapah and Vindhyan systems, not the basalt of the Trap. Option C is wrong because metamorphism of ancient rocks produced the gneisses of the Archaean Basement Complex. Option D is wrong because a central volcano throws out ash and builds a cone, whereas the Deccan lavas emerged quietly along fissures and spread far from their source. The weathering of this basalt gives the black cotton soil, or regur, that makes the Deccan India's cotton belt.
Read the full article: Geological Structure and Rock Systems of India Notes
Practice Questions
View allAny natural mass of mineral matter that makes up the earth's crust is _____.
- A.Garbage
- B.Rock
- C.Stone
- D.Fossil
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In geology a rock is any natural aggregate of one or more minerals that forms part of the earth's crust, whether it is hard like granite or soft like clay, and rocks are classified as igneous, sedimentary or metamorphic according to how they were formed.
Read the full explanation →Almost the whole of India's coal reserve belongs to which rock system?
- A.Dharwar system
- B.Vindhyan system
- C.Gondwana system
- D.Cuddapah system
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From the Upper Carboniferous onwards, thick beds of plant material accumulated in troughs and freshwater basins on the Gondwana landmass and were buried under sandstone and shale, giving the coalfields of the Damodar, Mahanadi, Godavari, Son and Wardha valleys.
Read the full explanation →The diamond-bearing conglomerates of India, including those of the Panna area, occur in which rock system?
- A.Archaean system
- B.Vindhyan system
- C.Gondwana system
- D.Tertiary system
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The sandstones, shales and limestones of this Purana system, which stretch across central India into the Son valley, contain the conglomerate beds in which diamonds are found, and the Panna mines of Madhya Pradesh as well as the diamonds once traded from the Kurnool area are associated with them.
Read the full explanation →Which rock system of India is the richest in metallic minerals such as iron ore, manganese and gold?
- A.Cuddapah system
- B.Dharwar system
- C.Vindhyan system
- D.Deccan Trap
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Named after the Dharwar region of Karnataka, it is the oldest metamorphosed sedimentary system in India and is described as highly metalliferous, yielding iron ore, manganese, gold, copper, lead, zinc and mica; the Champion gneiss of the Kolar gold field belongs to it.
Read the full explanation →Marble is formed by the metamorphism of which rock?
- A.Granite
- B.Sandstone
- C.Limestone
- D.Shale
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Limestone is a sedimentary rock composed mainly of calcium carbonate, and when it is subjected to heat and pressure its grains recrystallise into the dense, even-textured rock called marble.
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