Geology 2023 Paper I 50 marks Elucidate

Q6

(a) Elucidate an evolutionary trend of Equidae with Indian occurrence. (20 marks) (b) Discuss the pre-cambrian/cambrian boundary with Indian examples. (15 marks) (c) What is "Rainwater harvesting"? Describe its technique with neat sketches. (15 marks)

हिंदी में प्रश्न पढ़ें

(a) भारतीय उपलब्धता के साथ एक्विडी की विकासवादी प्रवृति पर प्रकाश डालिए । (20 अंक) (b) भारतीय उदाहरणों के साथ प्रीकैम्ब्रियन/कैम्ब्रियन सीमा की विवेचना कीजिए । (15 अंक) (c) "वर्षाजल छाजन क्या है" ? स्वच्छ आरेखों के साथ इसकी तकनीकी का वर्णन कीजिए । (15 अंक)

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Directive word: Elucidate

This question asks you to elucidate. 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 'elucidate' demands clear, illuminating explanation with logical progression. Structure: brief introduction on evolutionary principles → Part (a) ~40% word budget (Eohippus to Equus trend, Siwalik fossils, size/limb/dental evolution) → Part (b) ~30% (Ediacaran-Cambrian transition, Small Shelly Fossils, Indian sections like Krol-Tal, Bhander) → Part (c) ~30% (definition, surface/sub-surface techniques, sketches of check dams/percolation pits). Conclude with integrated significance of geological understanding for resource management.

Key points expected

  • Part (a): Progressive trends in Equidae—reduction of digits (4→1), hypsodonty development, cementum deposition, limb elongation; Indian Siwalik occurrences (Hipparion, Sivalhippus, Equus sivalensis at Haritalyangar, Nagri/Dhok Pathan formations)
  • Part (a): Stratigraphic context of Himalayan Foreland Basin, Murree-Dharmapuri-Siwalik succession, age constraints (Miocene-Pleistocene)
  • Part (b): Global stratotype sections (GSSP at Fortune Head, Newfoundland; alternative Meishan, China); biostratigraphic markers—Treptichnus pedum, Small Shelly Fossils, phosphatized embryos
  • Part (b): Indian reference sections—Krol-Tal transition (Lesser Himalaya), Bhander Group (Vindhyan), Cuddapah Supergroup; trace fossil evidence, carbon isotope excursions
  • Part (c): Definition and hydrogeological basis—recharge to groundwater, surface storage; techniques: rooftop harvesting with recharge pits, check dams/gabions in ephemeral streams, percolation tanks, subsurface dykes
  • Part (c): Indian implementation examples—Tamil Nadu mandatory RWH, Rajasthan traditional kunds/tankas, Gujarat check dams; sketches showing cross-section of recharge pit with filter media and percolation tank with spillway

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness25%12.5Precisely describes orthogenetic vs. mosaic evolution in Equidae; correctly identifies GSSP criteria and the 541 Ma boundary definition; explains hydraulic head and aquifer recharge principles for RWH without confusion between surface and subsurface systemsDescribes general evolutionary trends but conflates orthogenetic with adaptive radiation; mentions Cambrian explosion without boundary criteria; defines RWH but mixes up detention and retention structuresReverses evolutionary trends (e.g., claims digit number increased); confuses Precambrian-Cambrian with Permian-Triassic; describes RWH as only rooftop collection without groundwater linkage
Diagram / cross-section20%10Three quality sketches: (a) limb/dental evolution series with measurements, (b) idealized Krol-Tal lithostratigraphic column with fossil ranges, (c) labeled RWH cross-sections showing filter media, recharge shaft, and percolation tank with hydraulic gradientsTwo adequate diagrams with minor labeling errors; missing scale or legend; RWH sketch lacks flow arrows or filter detailsSingle diagram or none; poor freehand quality; diagrams copied without integration to text; no sketches for RWH techniques despite explicit demand
Field evidence20%10Cites specific Siwalik formations (Nagri, Dhok Pathan, Tatrot, Pinjor) with fossil localities; names Indian sections (Krol-Tal at Solan, Bhander Group at Son Valley) with lithology and fossil content; references CGWB/NGRI case studies for RWH impactMentions Siwalik fossils generally without formation names; refers to 'Vindhyan rocks' without specific sections; cites generic RWH success without agency dataNo Indian field occurrences; relies entirely on North American Equidae examples; boundary discussion lacks any Indian reference; RWH examples from non-Indian contexts only
Quantitative reasoning15%7.5Provides numerical data: Equus height (~1.5m vs. Eohippus 0.4m), hypsodonty index; boundary age 541±1 Ma with δ13C excursion values; RWH potential calculation (runoff coefficient × rainfall × catchment area) or recharge rate dataMentions size increase qualitatively; states 'around 540 Ma' without precision; gives rainfall figures without linking to harvestable volumeNo quantitative data; vague 'millions of years ago' dating; no calculations or estimates for water harvesting potential
Indian / economic relevance20%10Integrates Siwalik paleontology with Himalayan uplift chronology and monsoon evolution; links Precambrian-Cambrian boundary studies to India's Ediacaran fossil potential (Bhimbetka, Sonia); connects RWH to India's water security, groundwater depletion crisis, and Jal Shakti AbhiyanLists Indian examples without synthesis; mentions RWH importance but no policy connection; treats parts as isolated informationNo Indian context in any part; ignores economic/policy dimensions entirely; treats question as purely academic exercise without contemporary relevance

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