📘 IAS Prelims 2025 — GS-I Q.25 | Classroom Explanation

📌 Question

Q.25) Which of the following are the evidences of the phenomenon of continental drift?

I. The belt of ancient rocks from Brazil coast matches with those from Western Africa.
II. The gold deposits of Ghana are derived from the Brazil plateau when the two continents lay side by side.
III. The Gondwana system of sediments from India is known to have its counterparts in six different landmasses of the Southern Hemisphere.

Select the correct answer using the code given below:

(a) I and III only
(b) I and II only
(c) I, II and III
(d) II and III only

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✅ Correct Answer: (c)

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🧑‍🏫 Classroom Explanation

This question tests classical evidences of Continental Drift, a core theme in physical geography associated with Alfred Wegener’s Continental Drift Theory.

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🔍 Key Concept: Continental Drift

• Proposed by Alfred Wegener (1912)
• Suggests that continents were once joined together as a single landmass (Pangaea)
• Later drifted apart to their present positions

Evidence for continental drift comes from:

• Geological similarities
• Fossil correlations
• Palaeoclimatic indicators
• Mineral distribution patterns

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🔍 Statement-wise Analysis

✅ Statement I: Correct

• Radiometric dating has revealed that:

• Ancient rock belts (~2000 million years old) along the Brazilian coast
• Closely match those along Western Africa

• Such matching rock formations across the Atlantic indicate that:

• South America and Africa were once joined
• The Atlantic Ocean opened later (post-Jurassic)

➡️ Hence, Statement I is correct.

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✅ Statement II: Correct

• The gold deposits of Ghana are largely placer deposits
• Ghana itself lacks adequate source rocks for gold

• The corresponding gold-bearing source rocks exist in the Brazilian Plateau
• When Africa and South America were joined, gold was deposited continuously
• After continental separation, gold deposits remained split across continents

➡️ Hence, Statement II is correct.

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✅ Statement III: Correct

• The Gondwana system of sediments found in India has counterparts in:

• Africa
• Madagascar
• Falkland Islands
• Antarctica
• Australia

• These sedimentary sequences include:

• Thick glacial tillite layers
• Indicating widespread ancient glaciation

• Such identical sedimentary and climatic histories across southern continents strongly support continental drift

➡️ Hence, Statement III is correct.

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🧮 Logical Elimination (UPSC Style)

• Statement I → True
• Statement II → True
• Statement III → True

➡️ All statements are correct.

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🎯 Final Answer

✅ Correct Answer: (c) I, II and III

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🔗 Bridge Points (Future Questions)

• Continental Drift vs Plate Tectonics
• Gondwanaland vs Laurasia
• Tillite as palaeoclimatic evidence
• Matching fossils: Mesosaurus, Glossopteris

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📍 GS Mapping

GS Paper I
Subject: Geography
Theme: Geomorphology — Continental Drift
Nature: Static Conceptual

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