Geology 2025 Paper I 50 marks Justify

Q3

(a) Waves are responsible for modifying the coastal geomorphology. Justify the statement giving suitable examples and neat diagrams. (20 marks) (b) Explain how the Remote Sensing and Geographic Information System (GIS) may help in delineation of Groundwater potential zone ? (15 marks) (c) Using neat sketches describe various types of Thrust geometries formed in a compressional regime. (15 marks)

हिंदी में प्रश्न पढ़ें

(a) तरंगे तटीय भूआकृतियों को रूपांतरित करने के लिए उत्तरदायी हैं । तर्कसंगत उदाहरण एवं स्पष्ट चित्रों की सहायता से कथन की व्याख्या कीजिये । (20 अंक) (b) सुदूर संवेदन तथा भौगोलिक सूचना प्रणाली (जी. आई. एस.) किस प्रकार भूजल संभाव्य क्षेत्र के अंकन में सहायक हो सकते हैं ? (15 अंक) (c) स्पष्ट चित्रों की सहायता से संपीड़नीय व्यवस्था में बने विभिन्न प्रकार की क्षेपभ्रंश ज्यामिति का वर्णन कीजिये । (15 अंक)

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Directive word: Justify

This question asks you to justify. 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 'justify' in part (a) demands evidence-based argumentation with cause-effect reasoning, while parts (b) and (c) require 'explain' and 'describe' respectively. Allocate approximately 40% of time/words to part (a) given its 20 marks, and roughly 30% each to parts (b) and (c). Structure with a brief integrated introduction, then three clearly demarcated sections addressing each sub-part sequentially, using diagrams strategically within each section rather than as an afterthought.

Key points expected

Part (a): Wave mechanics (constructive vs destructive waves), wave refraction and longshore drift, erosional landforms (wave-cut platforms, stacks, arches, caves), depositional landforms (spits, bars, tombolos, beaches), with Indian examples like Chhera Dwip in Bangladesh/India, Marina Beach, or Kerala backshore barriers
Part (b): RS data sources (Landsat, Sentinel, ASTER) for lithology, lineament and drainage mapping; GIS overlay analysis of slope, soil, drainage density, rainfall, land use; integration of thematic layers for groundwater potential index (GWP); validation through well yield data
Part (c): Thrust fault geometry classification—imbricate fan, duplex structure (antiformal stack), triangle zone, passive roof duplex, and foreland-vergent vs hinterland-vergent systems; stress orientations and fault-bend/fault-propagation folding relationships
Cross-cutting application: Integration of geomorphic process understanding with modern analytical tools (RS/GIS) and structural geometry, demonstrating how surface processes, technology, and tectonics interconnect in geological studies
Diagrammatic requirements: Wave approach and refraction diagrams, coastal landform sketches, RS/GIS workflow schematic, thrust geometry cross-sections with displacement vectors and stress ellipses

Evaluation rubric

Dimension	Weight	Max marks	Excellent	Average	Poor
Concept correctness	25%	12.5	Demonstrates precise understanding of wave dynamics (orbital motion, breaker types, wave base), accurate RS/GIS methodology including specific sensors and algorithms (NDVI, NDWI, AHP weighting), and structurally sound thrust terminology (hanging wall/footwall, cut-off angle, transport direction); correctly distinguishes between emergent and submergent coasts in part (a), supervised vs unsupervised classification in part (b), and recognizes kinematic compatibility in thrust systems for part (c)	Shows generally correct concepts but with minor errors—confuses constructive/destructive wave characteristics, describes RS/GIS in generic terms without specific sensor or algorithm names, or mislabels thrust components; understands basic definitions but lacks mechanistic depth	Fundamental misconceptions present—attributes coastal features solely to tides or currents ignoring waves, treats RS and GIS as interchangeable without distinct roles, or confuses thrusts with normal/strike-slip faults; significant geological inaccuracies throughout
Diagram / cross-section	25%	12.5	Provides minimum 4-5 neat, labeled diagrams: for (a) wave refraction around headland with orthogonal lines, and one erosional plus one depositional landform; for (b) clear RS-GIS workflow or multi-criteria overlay schematic; for (c) at least two distinct thrust geometries (e.g., imbricate fan and duplex) with proper stratigraphic markers, displacement arrows, and stress orientations; all diagrams integrate with text and use standard geological symbols	Includes 2-3 diagrams with basic labels but missing critical elements—wave diagrams without orthogonal lines, thrust sketches without displacement indicators or vergence direction, or RS/GIS described only textually; diagrams present but not fully integrated with explanation	Single diagram or none; poorly drawn with missing labels, incorrect geometries (e.g., thrusts shown as vertical faults), or diagrams that contradict written text; diagrams appear as afterthoughts without explanatory value
Field evidence	20%	10	Cites specific, geographically located examples for each part: for (a) Vishakhapatnam coast (emergent), Kerala barrier islands (depositional), or Diu headland erosion; for (b) references CGWB/NGRI case studies from Rajasthan, Gujarat or Tamil Nadu where RS/GIS successfully delineated aquifers; for (c) Himalayan examples like Main Boundary Thrust, Main Central Thrust duplex structures, or Salt Range triangle zone with documented structural data	Mentions generic examples without specific locations (e.g., 'beaches in India' or 'the Himalayas') or conflates similar features; shows awareness that field evidence exists but cannot cite specific studies or locations with precision	No field examples provided, or examples are factually wrong (e.g., citing tsunami as wave erosion example without distinction, or locating thrust geometries in extensional settings like the Western Ghats escarpment)
Quantitative reasoning	15%	7.5	Incorporates quantitative elements: for (a) wave parameters (wave height, period, wavelength relationships), Hjulström diagram thresholds, or longshore drift rates; for (b) mentions specific spatial resolutions (Landsat 30m, Sentinel-10m), weighting schemes in AHP, or validation statistics (ROC curves, kappa coefficient); for (c) includes dip angles, displacement-to-thickness ratios, or shortening calculations; demonstrates dimensional awareness throughout	Acknowledges quantitative aspects descriptively without numerical values—mentions 'high resolution' without specifying, 'steep dip' without angles, or 'significant displacement' without magnitude; qualitative treatment of inherently quantitative concepts	Entirely qualitative treatment where quantitative reasoning is expected; no awareness of measurement scales, resolution requirements, or geometric relationships; treats all processes as purely descriptive
Indian / economic relevance	15%	7.5	Explicitly connects to Indian contexts and societal value: for (a) coastal erosion threats to Odisha-Puducherry coast, CRZ regulations, or port infrastructure (Vizhinjam, Ennore); for (b) groundwater depletion in Punjab-Haryana, Rajasthan's paleochannel exploration (Luni, Saraswati), or aquifer mapping for Jal Jeevan Mission; for (c) hydrocarbon exploration relevance (Cambay Basin thrusts, Assam fold belt), tunneling hazards, or seismic hazard assessment in Himalaya; demonstrates policy awareness	Mentions Indian locations without elaborating significance, or notes economic importance generically ('groundwater is important for agriculture') without specific sectoral or policy linkages; awareness present but not developed	No Indian examples whatsoever, or purely foreign examples (California coast, Swiss Alps thrusts, US aquifer studies); completely misses economic/policy dimensions despite their clear relevance to all three sub-parts

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