Geology 2025 Paper I 50 marks 150 words Compulsory Discuss

Q5

Answer the following questions in about 150 words each: (a) Discuss favourable conditions for fossilization. (10 marks) (b) Discuss different concepts of biozonation with neat diagrams. (10 marks) (c) Describe the lithology, type locality, age and depositional environment of Blaini Boulder Bed. (10 marks) (d) What engineering properties make Marble, Sandstone and Granite useful as building stone ? (10 marks) (e) Explain different generic type of water and their significance in water supply. (10 marks)

हिंदी में प्रश्न पढ़ें

निम्नलिखित प्रश्नों में से प्रत्येक का लगभग 150 शब्दों में उत्तर दीजिये : (a) जीवाश्मन के लिये अनुकूल परिस्थितियों का वर्णन कीजिए । (10 अंक) (b) जैव मंडलन की विभिन्न अवधारणाओं का सचित्र वर्णन कीजिए । (10 अंक) (c) ब्लैनी गोलाश्म-संस्तर के शैललक्षण, प्रतीकात्मक क्षेत्र, आयु तथा निक्षेपण पर्यावरण का वर्णन कीजिये । (10 अंक) (d) संगमरमर, बलुआपथर तथा ग्रेनाइट के कौन से अभियांत्रिकी गुण उनको इमारती पत्थर के लिये उपयोगी बनाते हैं ? (10 अंक) (e) जल की विभिन्न जनित प्रकार तथा उनकी जल आपूर्ति में सार्थकता पर प्रकाश डालिए । (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 sub-parts. Allocate approximately 30 words (20% time) per sub-part, with slightly more emphasis on (b) biozonation due to its diagram requirement and (c) Blaini Boulder Bed due to its multi-component factual demand. Structure each sub-part as: brief introduction → systematic coverage of all directive components → concluding significance statement. For (b), reserve space for two labeled diagrams; for (d), use comparative tabular format.

Key points expected

(a) Fossilization: Rapid burial, possession of hard parts, anaerobic environment, absence of diagenetic dissolution, and examples from Siwalik or Vindhyan fossils
(b) Biozonation: Range zone, Assemblage zone, Acme zone, Oppel zone concepts with stratigraphic range diagrams showing overlapping species distributions
(c) Blaini Boulder Bed: Purple/green shale matrix with exotic clasts, Blaini village (Mussoorie), Lower Cambrian, glacial-marine dropstone environment of Marinoan glaciation equivalent
(d) Building stones: Marble (low porosity, 2.6-2.7 g/cc, polishability), Sandstone (porosity 5-25%, compressive strength 20-170 MPa, workability), Granite (compressive strength 100-250 MPa, durability, low water absorption)
(e) Water types: Meteoric (recharge significance), Connate (formation water, oil field association), Juvenile (magmatic, geothermal), Metamorphic (orogenic belts); mention Indian aquifer vulnerability

Evaluation rubric

Dimension	Weight	Max marks	Excellent	Average	Poor
Concept correctness	25%	12.5	Precise geological terminology throughout: for (a) distinguishes permineralization from replacement; for (b) correctly defines each biozone type with stratigraphic boundaries; for (c) accurately places Blaini in Tal Group, Lower Cambrian; for (d) cites specific engineering values; for (e) correctly classifies water origins without conflating terms	Generally correct concepts but with minor errors: vague on biozone boundaries, misplaces Blaini as Precambrian, omits specific strength values, conflates connate and formation water	Fundamental misconceptions: treats fossilization as only body fossils, confuses biozones with lithostratigraphy, identifies Blaini as glacial till without marine context, lists aesthetic rather than engineering properties, misclassifies all water types
Diagram / cross-section	20%	10	For (b): two neat, labeled diagrams showing (i) range zones with first appearance datum (FAD) and last appearance datum (LAD), and (ii) Oppel zone as overlapping ranges; for (c): optional sketch of dropstone in marine shale; diagrams integrated with text, properly scaled, with stratigraphic column orientation	One diagram for (b) covering basic range zone concept but missing FAD/LAD labels or Oppel zone; diagrams present but poorly integrated, missing scale or orientation	No diagrams despite explicit instruction; or diagrams without labels, wrong orientation (time vs. space axes reversed), or depicting lithostratigraphy instead of biostratigraphy
Field evidence	20%	10	Specific Indian field citations: for (a) Siwalik vertebrate fossils at Haritalyangar or Gondwana plant fossils; for (c) precise Mussoorie Syncline location, clast lithologies (granite, quartzite); for (d) Makrana marble, Jodhpur sandstone, Chittoor granite quarries; for (e) examples from Deccan Traps aquifers or Ganga basin	Generic field references without specificity: mentions 'Himalayan fossils' without site, 'Indian building stones' without quarry locations, 'groundwater' without aquifer names	No field evidence; purely theoretical treatment; or incorrect field associations (e.g., Blaini in Kashmir, Makrana as sandstone)
Quantitative reasoning	15%	7.5	Numerical specificity where applicable: for (d) compressive strength ranges (Marble: 50-150 MPa, Sandstone: 20-170 MPa, Granite: 100-250 MPa), specific gravity, porosity percentages; for (e) approximate residence times or TDS ranges for water types; for (c) clast size ranges in Blaini	Some quantitative data but imprecise: 'high strength' without values, 'low porosity' without percentages, order-of-magnitude errors in values	No quantitative data where clearly applicable; purely qualitative description of engineering properties; or invented/incorrect numerical values
Indian / economic relevance	20%	10	Strong Indian context: for (a) fossil parks (Siwalik, Gondwana) and geoheritage; for (b) application in K-T boundary studies of Deccan Traps; for (c) Blaini as key marker horizon in Lesser Himalaya hydrocarbon exploration; for (d) specific monuments (Taj Mahal-Makrana, Red Fort-Dholpur) and export economics; for (e) NAPCC water security, arsenic/fluoride issues in connate water mixing	Some Indian relevance mentioned but superficial: lists Indian examples without connecting to economic or policy significance; generic 'important for construction' statements	No Indian context; Western-only examples (Burgess Shale, Grand Canyon biozones, Carrara marble); or irrelevant economic discussion not tied to specific sub-parts

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