Geology 2025 Paper I 50 marks 150 words Compulsory Discuss

Q1

Answer the following questions in about 150 words each: (a) Discuss the position of Astroid belt within the solar system and comment on the composition of meteorites. (10 marks) (b) What are sheath folds ? Discuss the deformational conditions of their formation. (10 marks) (c) What is Global Positioning System (GPS) ? Explain its geological applications. (10 marks) (d) Discuss the statement giving suitable examples. "Physical weathering adds to the effectiveness of Chemical weathering". (10 marks) (e) Discuss the types of Penetrative and Non-penetrative lineations with the help of suitable diagrams and throw light on their genesis. (10 marks)

हिंदी में प्रश्न पढ़ें

निम्नलिखित प्रश्नों में से प्रत्येक का लगभग 150 शब्दों में उत्तर दीजिए : (a) सौर्य मण्डल में क्षुद्रग्रहीय पट्टी की स्थिति तथा उल्कापिंडों के संघटन का वर्णन कीजिए । (10 अंक) (b) शीथ वलन क्या होते हैं ? इनकी उत्पत्ति की विरूपण अवस्था की विवेचना कीजिए । (10 अंक) (c) ग्लोबल पोजिशनिंग सिस्टम (जी. पी. एस.) क्या है ? इसके भूवैज्ञानिक उपयोगों को समझाइये । (10 अंक) (d) "भौतिक अपक्षय रासायनिक अपक्षय की क्षमता को बढ़ाता है" । इस कथन की उचित उदाहरणों द्वारा विवेचना कीजिए । (10 अंक) (e) उचित आरेखों की सहायता से विभिन्न प्रकार के भेदक तथा गैर-भेदी सरेखण की विवेचना कीजिये तथा इनकी उत्पत्ति पर प्रकाश डालिये । (10 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 across all five parts with clear reasoning and examples. Allocate approximately 30 words (20% time) per sub-part: (a) locate asteroid belt between Mars-Jupiter with Kirkwood gaps and meteorite classes; (b) define sheath folds with hinge rotation and high strain conditions; (c) GPS satellite configuration with crustal deformation monitoring; (d) synergistic weathering with Indian examples like exfoliation aiding lateritization; (e) contrast penetrative (S1 foliation, L1 lineation) vs non-penetrative (crenulation, millions) lineations with genesis. Prioritize diagrams for (b) and (e) where structural visualization is essential.

Key points expected

  • (a) Asteroid belt position: 2.1-3.3 AU between Mars (1.5 AU) and Jupiter (5.2 AU); Kirkwood gaps resonant with Jupiter; meteorite composition: chondrites (primitive), achondrites (differentiated), iron-stony-iron; carbonaceous chondrites and amino acids significance
  • (b) Sheath folds: highly non-cylindrical folds with curved hinge lines in XZ plane of strain ellipsoid; type 3 interference patterns; formation in high shear strain zones (>γ=10), non-coaxial deformation, mylonitic zones
  • (c) GPS: NAVSTAR constellation, trilateration principle, differential GPS; geological applications: crustal strain measurement (Himalayan convergence ~18 mm/yr), earthquake cycle monitoring, landslide detection, GSI network
  • (d) Physical-chemical weathering synergy: increased surface area from fracturing enhances reaction rates; examples: spheroidal weathering (jointing + hydration), laterite profile development, freeze-thaw accelerating oxidation in Himalayas
  • (e) Penetrative lineations: L1 stretching lineation, mineral lineation (hornblende), intersection lineations; non-penetrative: millions, crenulation lineations, slickensides; genesis: tectonic vs superposed deformation, scale-dependent strain partitioning

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness25%12.5Precise astronomical distances for (a); correct strain ellipsoid orientation and shear strain magnitudes for sheath folds in (b); accurate GPS error margins and GSI applications for (c); correct thermodynamic explanation of surface area-reaction rate relationship for (d); distinguishes penetrative (grain-scale, homogeneous) vs non-penetrative (heterogeneous, domainal) strain for (e)Generally correct positions and definitions but vague on quantitative aspects; confuses sheath fold geometry with similar structures; generic GPS description without geological specificity; states weathering relationship without mechanism; incomplete lineation classificationMajor conceptual errors: asteroid belt beyond Jupiter; sheath folds as fold interference without strain context; GPS described as only navigation tool; treats weathering types as independent; cannot define penetrative vs non-penetrative distinction
Diagram / cross-section20%10Clear 3D block diagram of sheath fold showing XZ section curvature and type 3 interference for (b); labeled strain ellipsoid with lineation orientations for (e); solar system schematic with Kirkwood gaps for (a); weathering profile with joint sets for (d)Attempted diagrams but poor labeling or incorrect orientations; 2D representation of 3D structures; missing scale or strain axes; diagrams mentioned but not executedNo diagrams where essential (parts b and e); or diagrams completely misrepresent structural geometry; decorative sketches without geological information
Field evidence15%7.5Cites specific meteorite falls (Allende, Murchison) for (a); references Himalayan shear zones (Main Central Thrust, South Tibetan Detachment) for sheath folds in (b); names GSI GPS stations or specific landslide/earthquake studies for (c); Indian laterite profiles (Kerala, Goa) or Deccan Trap spheroidal weathering for (d); specific structural domains (Dharwar, Aravalli) for lineation studies in (e)Generic field references without specificity; mentions 'Himalayan orogeny' or 'Indian cratons' without locating structures; no actual field examples citedNo field evidence provided; purely theoretical treatment; incorrect attribution of examples to wrong geological settings
Quantitative reasoning15%7.5Provides AU distances, Kirkwood gap periodicities (3:1, 5:2 resonances) for (a); shear strain values (γ>10), aspect ratios for sheath folds in (b); GPS precision (cm-level), convergence rates for India-Asia collision for (c); surface area increase ratios or reaction rate dependencies for (d)Mentions quantitative aspects without values; 'high strain' or 'precise measurements' without numbers; order-of-magnitude errorsNo quantitative treatment where expected; incorrect orders of magnitude; confuses units (km vs AU, strain vs stress)
Indian / economic relevance25%12.5Meteorite research at Physical Research Laboratory, Ahmedabad for (a); economic mineralization in shear zones (Kolar gold, Singhbhum copper) linked to sheath fold structures for (b); GSI's GPS network for seismic hazard assessment, landslide monitoring in Himalayas for (c); bauxite/laterite economic deposits, Deccan Trap weathering profiles for construction materials for (d); structural controls on Indian ore deposits (Dharwar craton lineations) for (e)Brief mention of Indian localities without economic or societal significance; generic references to 'Himalayan studies' or 'Indian geology'No Indian context; misses opportunities to connect to national priorities (mineral security, hazard assessment, space research); purely Euro-American examples

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