General Studies 2022 GS Paper I 10 marks 150 words Compulsory Describe

Q4

Describe the characteristics and types of primary rocks. (Answer in 150 words) 10

हिंदी में प्रश्न पढ़ें

प्राथमिक चट्टानों की विशेषताओं एवं प्रकारों का वर्णन कीजिए। (150 शब्दों में उत्तर दें)

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Directive word: Describe

This question asks you to describe. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.

See our UPSC directive words guide for a full breakdown of how to respond to each command word.

How this answer will be evaluated

Approach

The directive 'describe' requires a systematic portrayal of primary rocks' defining features and their classification. Structure: brief introduction defining primary (igneous) rocks → body covering characteristics (texture, mineral composition, cooling history) → types (intrusive/plutonic and extrusive/volcanic with sub-types) → concise conclusion on their geological significance.

Key points expected

Definition: Primary rocks are igneous rocks formed from cooling and solidification of magma/lava; also called parent rocks of other rock types
Key characteristics: crystalline texture, absence of fossils, no stratification, hard and massive, chemically active minerals
Intrusive/plutonic types: granite, syenite, diorite, gabbro, peridotite (coarse-grained, slow cooling)
Extrusive/volcanic types: basalt, andesite, rhyolite, obsidian, pumice (fine-grained/glassy, rapid cooling)
Indian examples: Deccan Trap basalt (world's largest flood basalt), granites of Rajasthan/Gujarat, charnockite of Tamil Nadu

Evaluation rubric

Dimension	Weight	Max marks	Excellent	Average	Poor
Demand-directive understanding	20%	2	Correctly interprets 'describe' as requiring detailed portrayal of both characteristics AND types; covers both aspects proportionally without drifting into formation processes or economic uses	Covers characteristics and types but with imbalanced treatment; minor confusion between 'primary' and 'igneous' terminology	Misinterprets directive as 'explain' or 'discuss' formation; omits either characteristics or types entirely; treats all rocks as primary
Content depth & accuracy	20%	2	Precise geological terminology (phaneritic, aphanitic, porphyritic textures); accurate distinction between intrusive/extrusive based on cooling rates; correct mineral associations	Basic correct information but vague on textures; minor errors in classification (e.g., calling basalt intrusive) or mineral composition	Confuses primary with sedimentary/metamorphic; wrong classification (e.g., limestone as primary); fundamental errors in cooling-depth relationship
Structure & flow	20%	2	Logical progression: definition → characteristics → classification → sub-types; clear paragraphing; maintains 150-word discipline with concise expression	Adequate structure but some mixing of characteristics within types; slightly over/under word limit; readable but not optimally organized	Disorganized jumping between points; no clear separation of characteristics from types; illegible or extremely poor paragraphing
Examples / case-law / data	20%	2	Specific Indian examples: Deccan Traps (basalt), Singhbhum granite, Rajmahal traps, charnockite of Nilgiri-Palani hills; mentions geographic significance	Generic examples without Indian specificity (just 'granite' or 'basalt'); or only one Indian example mentioned	No examples at all; wrong examples (sedimentary/metamorphic rocks cited); purely international examples ignoring Indian context
Conclusion & analytical edge	20%	2	Brief but insightful conclusion on significance: foundation of crust, source of soil minerals, economic importance (granite industry, Deccan Trap fertility); links to rock cycle	Generic concluding statement without specific value-addition; or abrupt ending without conclusion	No conclusion; or lengthy conclusion eating into body content; irrelevant philosophical or environmental conclusion

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