Geology 2022 Paper I 50 marks Illustrate

Q4

(a) Illustrate the common brittle-ductile shear zone structures. Using the stress ellipsoid, deduce the mechanism of faults. (20 marks) (b) Describe the various platforms and sensors used in Remote Sensing. (15 marks) (c) What are the weathering stages of soil formation? Discuss the active and passive factors of soil formation. (15 marks)

हिंदी में प्रश्न पढ़ें

(a) भंगुर-तन्य अपरूपण क्षेत्र की साधारण संरचनाओं को उदाहरण सहित स्पष्ट कीजिए। प्रतिबल दीर्घवृत्तज का उपयोग कर भंश क्रियाविधि को दर्शाइए। (20 अंक) (b) सुदूर संवेदन में उपयोग किए जाने वाले विभिन्न प्लेटफॉर्म तथा संवेदक का वर्णन कीजिए। (15 अंक) (c) मृदा निर्माण के अपक्षय चरण क्या हैं? मृदा निर्माण के सक्रिय एवं निष्क्रिय कारकों का वर्णन कीजिए। (15 अंक)

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Directive word: Illustrate

This question asks you to illustrate. 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 'illustrate' for part (a) demands visual demonstration with explanatory text; parts (b) and (c) require descriptive coverage. Allocate approximately 40% of time/words to part (a) given its 20 marks, with ~30% each to parts (b) and (c). Structure: brief introduction → systematic treatment of each sub-part with diagrams for (a), tabulated comparison for (b), and process-oriented explanation for (c) → concluding synthesis on applied geological techniques.

Key points expected

  • Part (a): Distinguish brittle (cataclasite, fault breccia, pseudotachylyte) versus ductile (mylonite, protomylonite, ultramylonite) shear zone structures with microstructural criteria
  • Part (a): Apply stress ellipsoid (σ1 > σ2 > σ3) to deduce normal, reverse, and strike-slip fault mechanisms showing appropriate σ orientations
  • Part (b): Classify remote sensing platforms as ground-based, aerial (balloons, aircraft, UAVs), and spaceborne (LEO, GEO, sun-synchronous, polar orbits)
  • Part (b): Detail sensor types across EM spectrum—panchromatic, multispectral, hyperspectral, thermal infrared, microwave (active: SAR; passive: radiometers), and LiDAR
  • Part (c): Elucidate weathering stages: physical disintegration → chemical decomposition → synthesis of clay minerals → profile development (O-A-B-C-R horizons)
  • Part (c): Differentiate active factors (climate, organisms, relief/time as dynamic agents) from passive factors (parent material, topography as static templates)

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness25%12.5Precisely defines S-C fabrics, σ-δ porphyroclasts, and shear sense indicators; correctly relates stress ellipsoid axes to fault types (Andersonian theory); accurately distinguishes whiskbroom vs pushbroom sensors, active vs passive systems; properly sequences soil horizon development with correct terminology (eluviation/illuviation)Basic definitions of shear zone types and fault classes present but conflates brittle-ductile transition; generic sensor lists without operational principles; soil stages described but factors confused or parent material omittedFundamental errors such as swapping σ1/σ3 orientations, confusing SAR with optical sensors, or describing soil as purely biological product without weathering stages
Diagram / cross-section20%10For (a): labeled 3D stress ellipsoid with fault plane orientation; cross-sections showing S-C fabric geometry, shear band asymmetry; for (b): schematic orbit diagrams; for (c): idealized soil profile with horizon annotations—minimum 4 high-quality diagramsSimple 2D stress diagrams without 3D perspective; generic shear zone sketches without kinematic indicators; basic soil profile lacking horizon boundaries or chemical gradientsAbsent or incorrect diagrams; misoriented stress ellipsoids; diagrams copied without integration into explanatory text
Field evidence15%7.5Cites specific Indian examples: Main Central Thrust mylonites (Himalaya), Singhbhum shear zone cataclasites; Bhuj earthquake remote sensing applications; laterite profiles of Western Ghats, black cotton soil vertisols of Deccan Traps with field observable characteristicsMentions general field contexts (Himalayan faults, Indian soils) without specific localities or observable criteria; remote sensing examples limited to Landsat/IRS without application contextNo field examples; purely theoretical treatment; incorrect attribution of Indian geological features
Quantitative reasoning20%10Provides stress ratios (R = (σ2-σ3)/(σ1-σ3)) for fault stability; spatial/spectral resolution values for sensors (e.g., LISS-IV: 5.8m, RISAT: 1-50m); soil formation rates (mm/kyr); temperature/precipitation thresholds for lateritization; Mohr-Coulomb failure envelope sketch with τ-σ relationshipsMentions resolution concepts without specific values; qualitative stress descriptions; general statements about slow soil formation without ratesNo quantitative parameters; incorrect units; confuses spatial and spectral resolution
Indian / economic relevance20%10Links shear zones to Indian mineralization (gold in Hutti-Maski, copper in Singhbhum); emphasizes IRS/Resourcesat/Cartosat applications for groundwater, agriculture, disaster management; connects soil studies to NMSA, land capability classification for Indian agriculture; mentions GSI/NGRI contributionsBrief mention of Indian satellites or soil types without application linkage; generic economic importance statementsNo Indian context; foreign examples exclusively; misses policy relevance entirely

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