Fossils of plants and animals are generally found in which type of rock?
- A.Igneous rocks
- B.Sedimentary rocks
- C.Metamorphic rocks
- D.Plutonic rocks
Correct answer
Explanation
The correct answer is B, sedimentary rocks. Sediment settles in layers at ordinary temperatures, so the remains of organisms buried with it are preserved as the layers are compacted and cemented, which is why sedimentary rocks are also called stratified rocks and why the history of life is read from them. Option A is wrong because igneous rocks solidify from magma or lava at temperatures that destroy organic remains altogether. Option C is wrong because metamorphism works by heat and pressure, which deform, recrystallise or wipe out whatever fossils the parent rock may have held; a fossil may survive in a mildly altered rock, but such rocks are not the usual answer. Option D is wrong because plutonic rocks are simply intrusive igneous rocks, such as granite, that cooled deep below the surface and are therefore fossil-free as well.
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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