Geology 2025 Paper I 50 marks Discuss

Q2

(a) What do you understand by continental drift ? Discuss various geological evidences in favour of continental drift. (20 marks) (b) Geomorphic diversity is controlled by a number of endogenic and exogenic processes. Discuss this statement. (15 marks) (c) Describe morphotectonic features characteristic of rejuvenation in a mountaineous terrain. (15 marks)

हिंदी में प्रश्न पढ़ें

(a) महाद्वीपीय विस्थापन से आप क्या समझते हैं ? महाद्वीपीय विस्थापन के विभिन्न भूवैज्ञानिक साक्ष्यों का वर्णन कीजिये । (20 अंक) (b) भू-आकृति विविधता विभिन्न अंतर्जनित तथा बहिर्जनित क्रियाओं से नियंत्रित होती है । इस कथन की विवेचना कीजिए । (15 अंक) (c) पर्वतीय भूभाग में पुनर्युवन संलक्षणी विवर्तनिक भूआकृतियों का वर्णन कीजिये । (15 अंक)

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Directive word: Discuss

This question asks you to discuss. 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 'discuss' demands a balanced, analytical treatment with evidence-based reasoning across all three parts. Allocate approximately 40% of time/words to part (a) given its 20 marks, and roughly 30% each to parts (b) and (c). Structure: brief integrated introduction → systematic treatment of (a) Wegener's hypothesis with evidences, (b) process-driven geomorphic diversity with Indian examples, (c) rejuvenation landforms with Himalayan/Deccan references → synthesizing conclusion on dynamic Earth processes.

Key points expected

  • Part (a): Wegener's continental drift hypothesis (1912), palaeomagnetic evidence, matching coastlines (Africa-South America), fossil correlations (Glossopteris, Mesosaurus), rock type and structural continuity (Appalachian-Caledonian belt), palaeoclimatic evidence (tillites in India/Africa/Australia)
  • Part (b): Endogenic controls (tectonics, volcanism, isostasy) and exogenic controls (weathering, erosion, deposition, climate) on landform diversity; specific Indian examples like Western Ghats escarpment, Meghalaya plateau, Thar dunes
  • Part (c): Rejuvenation concepts (Davisian cycles, epeirogenic uplift); morphotectonic features including incised meanders, river terraces, knickpoints, uplifted peneplains, antecedent/superimposed drainage; Indian examples from Himalayas (Siulik, Dun valleys) or Western Ghats
  • Integration: Link drift to geomorphic diversity through plate tectonics framework; connect rejuvenation to ongoing Himalayan orogeny
  • Critical perspective: Limitations of continental drift (lacking mechanism) superseded by plate tectonics; modern understanding of isostatic vs. tectonic uplift

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness25%12.5Precise definitions of continental drift, geomorphic diversity, and rejuvenation; accurate distinction between Wegener's original hypothesis and modern plate tectonics; correct application of Davisian vs. Penckian models in (c); no conflation of endogenic/exogenic processes in (b)Generally correct definitions with minor errors; some confusion between drift and plate tectonics; superficial treatment of rejuvenation mechanisms; endogenic/exogenic distinction present but not rigorously appliedFundamental misconceptions (e.g., equating drift with plate tectonics, confusing rejuvenation with simple erosion); missing core concepts; processes misclassified between endogenic and exogenic
Diagram / cross-section20%10Minimum 3 quality diagrams: (a) world map showing fossil/rock belt distributions or continental fit; (b) schematic cross-section showing endogenic-exogenic interaction; (c) river long profile with terraces/knickpoints or block diagram of rejuvenated terrain; all labelled, neat, and integrated with text2 diagrams present but with incomplete labelling or minor inaccuracies; diagrams mentioned but not well-executed; some integration with explanatory textSingle or no diagram; poorly drawn unlabelled sketches; diagrams irrelevant to question parts; text references to diagrams not actually drawn
Field evidence25%12.5Specific, accurate field evidence for (a): Gondwana fossils, Lystrosaurus, Glossopteris flora, tillite stratigraphy; for (b): named landform assemblages (e.g., Chambal badlands, Nilgiri plateau); for (c): specific Himalayan river terraces (Siwalik foothills), Western Ghat escarpment features, or Deccan plateau edgeGeneric mentions of fossils or landforms without specificity; some Indian examples but with location errors; field evidence stated without geological significance explainedNo specific field evidence; invented or incorrect examples; confusion between different geological provinces; evidence cited that actually contradicts the process described
Quantitative reasoning15%7.5Numerical data where relevant: rates of continental movement (cm/year), approximate timing of Gondwana breakup (180 Ma, 130 Ma, 65 Ma phases); uplift rates for rejuvenation (mm/year); drainage basin metrics; isostatic calculations implied; dates for fossil correlationsSome numerical mention (e.g., 'millions of years') without precision; qualitative treatment dominates; no calculation attempts where appropriateNo quantitative element; incorrect orders of magnitude; confused chronology (e.g., Paleozoic vs. Mesozoic timing errors)
Indian / economic relevance15%7.5Indian Gondwana basins (Damodar, Godavari, Mahanadi valleys) in (a); geomorphic controls on Indian agriculture, hydropower, mineral resources in (b); rejuvenation impacts on Himalayan hydropower projects, landslide hazards, groundwater in (c); explicit economic implicationsSome Indian examples present but not developed for economic significance; examples correct but relevance to human activity merely mentionedNo Indian examples; exclusively foreign case studies; missed opportunity to connect to Indian geological heritage or contemporary resource issues

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