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GeographyEasyAsked in: UPSC Civil Services · Prelims GS Paper I, 10 Oct 2021

The black cotton soil of India has been formed due to the weathering of

  1. A.brown forest soil
  2. B.fissure volcanic rock
  3. C.granite and schist
  4. D.shale and limestone

Correct answer

B. fissure volcanic rock

Explanation

The correct answer is B, fissure volcanic rock. Black cotton soil, or regur, formed from the weathering of the Deccan Trap basalt, lava that poured out through long cracks in the crust about 65 million years ago. This fissure eruption spread layer after layer of basalt over Maharashtra, western Madhya Pradesh, Gujarat and parts of Karnataka, Telangana and Andhra Pradesh, and the soil is found mainly on this plateau. It is rich in iron, lime, magnesium and potash but poor in nitrogen, phosphorus and organic matter, and its dark colour comes from titaniferous magnetite and humus. It holds moisture well, swells when wet and cracks deeply when dry, so it is said to 'plough itself', and it suits cotton. Option A is wrong because brown forest soil is itself a soil type, not the parent rock of regur. Option C is wrong because granite and schist weather mainly into red soils. Option D is wrong because shale and limestone are sedimentary rocks, not the source of the Deccan soils. Exam tip: regur means Deccan basalt, cotton and self-ploughing cracks.

Practice Questions

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Q2.GeographyAsked in: CDS · CDS-II 2017, GKMedium

Which of the following statements is/are correct? 1. Himalayan rivers have their origin in the snow-covered areas, hence are dry in winter season. 2. Rivers of the Peninsular Plateau have reached maturity. 3. Himalayan rivers depict all the three stages of normal cycle of erosion. Select the correct answer using the code given below.

  1. A.2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3
Show answer
Correct answer: C. 2 and 3 only

Himalayan rivers are perennial, so statement 1 is wrong, while statements 2 and 3 are correct. Himalayan rivers such as the Ganga, Indus and Brahmaputra rise from glaciers and snowfields and also get monsoon rain, so they flow all year round, including in winter.

Q3.GeographyAsked in: CDS · CDS-II 2017, GKMedium

Which of the following statements related to latitude are true? 1. Rainfall, temperature and vegetation vary with latitude. 2. The difference between the longest day and the shortest day increases with latitude. 3. Indira Point is located approximately at 6°45' N latitude. Select the correct answer using the code given below.

  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3
Show answer
Correct answer: D. 1, 2 and 3

All three statements about latitude are true. Latitude decides how directly the Sun's rays strike a place, so temperature, rainfall and the type of vegetation change from the equator towards the poles, from hot, wet rainforests to cold tundra.

Q4.GeographyAsked in: CDS · CDS-II 2017, GKMedium

Which of the following lakes is/are situated in Ladakh? 1. Tso Kar 2. Pangong Tso 3. Tsomgo 4. Tso Moriri Select the correct answer using the code given below.

  1. A.1 only
  2. B.2 and 3
  3. C.1, 2 and 4
  4. D.2 and 4 only
Show answer
Correct answer: C. 1, 2 and 4

Tso Kar, Pangong Tso and Tso Moriri are high-altitude lakes of Ladakh, while Tsomgo lies in Sikkim. Pangong Tso, at about 4,350 metres, is a long, narrow lake that stretches from Ladakh into Tibet, and most of its length lies on the Chinese side.