1. Consider the following statements about the sedimentary rocks:
1. Sedimentary rocks are formed at the earth’s surface by the hydrological system
2. The formation of sedimentary rocks involves the weathering of preexisting rocks
3. Sedimentary rocks contain fossils
4. Sedimentary rocks typically occur in layers
Which of these statements are correct?
(a) 1 and 2
(b) 1 and 4
(c) 2, 3 and 4
(d) 1, 2, 3 and 4
[I.A.S. (Pre) 2001]
Ans. (d) 1, 2, 3 and 4
- Sedimentary rocks are made up of sediment that builds up in places like lakes.
- The ocean carries the sediment to these places.
- This sediment can be pieces of other rocks, parts of plants and animals or even fossils.
- The sediment comes in layers called strata.
- All of these things are true about sedimentary rocks.
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2. Regarding sedimentary rocks which of the following statements is true?
(a) These are such rocks whose structure depend on temperature and pressure
(b) These rocks are crystal
(c) These rocks are deposited in layers
(d) These rocks cannot be formed in water
[39th B.P.S.C. (Pre) 1994]
Ans. (c) These rocks are deposited in layers
- Sedimentary rocks are made by pieces of sediment and other debris gathering in places like lakes.
- The ocean carries the sediment to where it is collected.
- These pieces of sediment can be pieces of existing rocks, remains of plants and animals, and fossils.
- Sedimentary rocks usually come in layers called strata.
- All of these statements are true about sedimentary rocks.
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3. Sandstone is flaky rock, because –
(a) It is formed in the desert
(b) It is formed due to Heat
(c) It is formed underwater
(d) It is formed on the mountain
[M.P.P.C.S. (Pre) 1993]
Ans. (c) It is formed underwater
- Sandstone is a type of sedimentary rock made up of small pieces of minerals, rocks, and organic materials.
- It usually forms in areas near the sea or in low-lying areas and turns into quartz, which is the most common type of grain found in sandstone.
- Other important sedimentary rocks include Chert, Conglomerate, Flints, and Silt.
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4. Which statement of the following is true for igneous rocks?
(a) These have little fossils
(b) They have porous for water
(c) They are both crystal and non-crystal
(d) These rocks have no silicas
[40th B.P.S.C. (Pre) 1995]
Ans. (c) They are both crystal and non-crystal
- Igneous rocks come from volcanic eruptions.
- The magma or lava cools and hardens to create these rocks, which have both a crystalline and non-crystalline texture.
- Option (c) is the correct answer, and the other statements are incorrect because igneous rocks are made up of silicate minerals, and don’t have fossils or layers.
- They also don’t provide much water.
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5. Which of the following rocks is not likely to contain fossils?
(a) Conglomerate
(b) Granite
(c) Shale
(d) Sandstone
[Jharkhand P.C.S. (Pre) 2013]
Ans. (b) Granite
- Granite is created from magma from a volcanic eruption but it does not contain fossils.
- Conglomerate, sandstone and shale are types of sedimentary rocks which do have fossils.
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6. Origin of Metamorphic rocks occurs from …….. rock?
(a) Igneous
(b) Sedimentary
(c) Both Igneous and Sedimentary
(d) None of the above
[Jharkhand P.C.S. (Pre) 2011]
Ans. (c) Both Igneous and Sedimentary
- Metamorphic is a word from Greek meaning “change in form”.
- Metamorphic rocks are formed when other types of rocks (sedimentary or igneous) are changed due to high temperatures from magma and pressure from tectonic movement.
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7. Which one of the following is not an example of Metamorphic rock?
(a) Marble
(b) Quartzite
(c) Slate
(d) Granite
[Uttarakhand P.C.S. (Pre) 2006]
Ans. (d) Granite
- Granite is not an example of Metamorphic rock; it is an Igneous rock.
- Metamorphic rocks that have come from Igneous rocks are, for example –
- Granite – Gneiss
- Basalt – Amphibolite
- Basalt – Schist
- Marble is a type of metamorphic rock which is created from sedimentary rock.
- Other types of metamorphic rocks that come from sedimentary rock include:
- Shale – Slate
- Limestone – Marble
- Chalk and dolomite – Marble
- Sandstone – Quartzite
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8. Which one of the following is not associated with the ‘group’?
(a) Gneiss
(b) Sandstone
(c) Limestone
(d) Shale
[Uttarakhand P.C.S. (Pre) 2012]
Ans. (a) Gneiss
- The types of rocks Limestone, Sandstone, and Shale are all sedimentary rocks, while Gneiss is a type of metamorphic rock.
- It is usually formed from Granite, but can also be made from Gabbro or Shale.
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