Geology 2023 Paper I 50 marks Discuss

Q8

(a) Discuss briefly how do chemical, physical and bacteriological properties determine the usability of ground-water. (20 marks) (b) Establish the ocean palaeobathymetry using marine fossils with the help of labelled diagram. (15 marks) (c) Discuss the palaeozoic sequence of Kumaun and Garhwal (Tethyan sequence) Himalaya. Add a note on its fossil contents. (15 marks)

हिंदी में प्रश्न पढ़ें

(a) भौम-जल की उपयोगिता को निर्धारित करने वाले रासायनिक भौतिक एवं जीवाण्विक गुणों की संक्षेप में चर्चा कीजिए । (20 अंक) (b) समुद्री जीवाश्मों का उपयोग करते हुए महासागर पुराअनुगभीर को अंकित आरेख की सहायता से स्थापित कीजिए । (15 अंक) (c) कुमाऊं और गढ़वाल (टेथियन अनुक्रम) हिमालय के पुराजीवी अनुक्रम का वर्णन कीजिए । उनके जीवाश्मी अंशों के बारे में एक टिप्पणी जोड़िए । (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' requires a comprehensive, analytical treatment with balanced coverage across all three sub-parts. Allocate approximately 40% of time/words to part (a) given its 20 marks weightage, and roughly 30% each to parts (b) and (c). Structure with a brief composite introduction, then three distinct sections addressing each sub-part sequentially, and a concluding synthesis on Himalayan-Tethyan hydrogeological connections. For part (b), dedicate specific effort to constructing a properly labelled depth-zonation diagram showing fossil assemblages against bathymetric gradients.

Key points expected

  • Part (a): Chemical parameters (TDS, hardness, fluoride, arsenic, nitrate) and their WHO/BIS permissible limits; physical properties (turbidity, colour, temperature, electrical conductivity) affecting potability; bacteriological indicators (total coliforms, fecal coliforms, E. coli) and waterborne disease risks; specific mention of Indian groundwater quality issues like arsenic in Bengal basin, fluoride in Rajasthan, and salinity in coastal aquifers
  • Part (a): Interlinkages between parameters—how chemical contamination affects bacteriological safety, and how physical properties influence chemical reactivity; classification schemes for groundwater usability (drinking, irrigation, industrial) based on integrated parameter assessment
  • Part (b): Principles of palaeobathymetric reconstruction using depth-sensitive fossil assemblages (benthic foraminifera, ostracods, radiolarians, depth-zoned molluscs); construction of a labelled diagram showing depth zones (littoral, neritic, bathyal, abyssal) with characteristic fossil indicators and their modern analogues
  • Part (c): Stratigraphic succession of Tethyan sequence in Kumaun-Garhwal: Tal Formation (Lower Palaeozoic quartz arenites), Garbyang Formation (Cambrian-Ordovician carbonates with archaeocyathids), Batal Formation (Silurian-Devonian), and Permian-Triassic marine sequences; structural position above Lesser Himalayan crystallines, separated by Main Central Thrust
  • Part (c): Fossil contents—archaeocyathid bioherms, trilobites, brachiopods, cephalopods, conodonts, and Permian fusulinid foraminifera; their Gondwanan versus Tethyan affinity and palaeogeographic significance; note on Permian-Triassic boundary events recorded in the sequence

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness25%12.5Demonstrates precise understanding of groundwater quality standards (WHO/BIS), accurate depth-zonation of marine fossil habitats for palaeobathymetry, and correct stratigraphic nomenclature of Tethyan sequence with proper chronostratigraphic assignments; correctly distinguishes between archaeocyathids and stromatolites, and between different groundwater contamination pathwaysShows generally correct concepts but with minor errors in stratigraphic order, fossil age assignments, or permissible limits of water quality parameters; may confuse some formations or misstate depth ranges for certain fossil groupsFundamental conceptual errors such as reversing stratigraphic succession, confusing Tethyan with Lesser Himalayan sequences, misidentifying bacteriological indicators, or presenting incorrect depth zonation for marine fossils
Diagram / cross-section20%10Produces a clear, properly labelled diagram for part (b) showing depth zones (0-200m littoral, 200-2000m neritic, 2000-4000m bathyal, >4000m abyssal) with representative fossil assemblages for each zone; includes scale, labels, and depth indicators; may supplement with a schematic cross-section of Tethyan stratigraphy for part (c)Presents a diagram with basic depth zonation but incomplete labelling, missing scale, or generic fossil representations without specific depth-sensitive taxa; OR omits diagram but describes visual elements adequately in textNo diagram attempted for part (b), or diagram is unlabelled, conceptually wrong (e.g., showing terrestrial fossils in abyssal zone), or illegible; fails to meet explicit question requirement
Field evidence20%10Cites specific Indian field examples: arsenic contamination in Bengal delta, fluoride in Nalgonda/Rajasthan for part (a); specific fossil localities like Garbyang, Malari, Batal in Kumaun-Garhwal for parts (b)-(c); references actual measured sections, fossil collections, or published stratigraphic columns from GSI/BSIP/Wadia Institute studiesMentions general field contexts without specific localities; refers to 'Himalayan fossils' or 'Indian groundwater' generically without pinning to named formations, sections, or documented case studiesNo field evidence cited; relies entirely on textbook generalizations without any reference to actual geological sections, measured stratigraphic columns, or documented groundwater quality surveys from Indian terrains
Quantitative reasoning15%7.5Provides specific numerical values: WHO/BIS drinking water standards (TDS 500/1500 mg/l, fluoride 1.0/1.5 mg/l, arsenic 10/50 μg/l), depth ranges for fossil zones, formation thicknesses where known; calculates water quality indices or discusses quantitative palaeodepth estimates from fossil ratios; uses isotope data where relevantStates some numerical ranges qualitatively ('high TDS', 'deep water') without precise figures; mentions that standards exist without quoting specific limits; gives approximate depth rangesEntirely qualitative treatment with no numbers, ranges, or quantitative relationships; fails to mention any permissible limits, depth measurements, or stratigraphic thickness data
Indian / economic relevance20%10Explicitly connects groundwater quality to India's drinking water security (Jal Jeevan Mission), agriculture (salinity/alkalinity hazards), and health burden (arsenicosis, fluorosis); links Tethyan palaeogeography to Himalayan petroleum prospectivity and geotourism; discusses economic implications of palaeobathymetric studies for offshore hydrocarbon exploration in Indian sedimentary basinsBrief mention of Indian relevance without elaboration—notes that groundwater quality is important or that Himalaya has economic minerals without specific policy, health, or resource implicationsNo Indian context provided; treats question as generic geology applicable anywhere; misses opportunity to connect to national water security, Himalayan geology significance, or Indian offshore exploration relevance

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