Q5
Answer the following questions in about 150 words each: (a) Enumerate the different types of siwalik fauna and discuss their palaeoecology. (10 marks) (b) Define fossil and give examples of two index fossils each from Palaeozoic, Mesozoic and Cenozoic Era and indicate the age of those index fossils. (10 marks) (c) Describe the lithology, palaeoenvironment and age of Krol Formation. (10 marks) (d) Briefly discuss the water-bearing properties of rocks. (10 marks) (e) What are the engineering properties of rocks that make them suitable for use as building materials? (10 marks)
हिंदी में प्रश्न पढ़ें
निम्नलिखित प्रश्नों में से प्रत्येक का लगभग 150 शब्दों में उत्तर दीजिए । (a) विभिन्न प्रकार के शिवालिक प्राणिजात के बारे में बतायें और उनकी पुरापारिस्थितिकी की विवेचना कीजिए । (10 अंक) (b) जीवाश्म को परिभाषित कीजिए और प्रत्येक पुराजीवी, मध्यजीवी एवं नूतनजीवी महाकल्पों के दो सूचक जीवाश्मों के उदाहरण दीजिए एवं उन सूचक जीवाश्मों की आयु बताइए । (10 अंक) (c) क्रोल शैल समूह के शैल लक्षण, पुरा वातावरण एवं आयु का वर्णन कीजिए । (10 अंक) (d) शैलों के जलधारी गुणों का संक्षिप्त में वर्णन कीजिए । (10 अंक) (e) शैलों के अभियांत्रिक गुण क्या हैं जो उन्हें निर्माण सामग्री के रूप में उपयोग के लिए उपयुक्त बनाते हैं ? (10 अंक)
Directive word: Enumerate
This question asks you to enumerate. 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
This multi-part question demands precise, structured responses across five distinct geological domains. Allocate approximately 30 words per mark (150 words × 5 parts = 750 total). For (a), enumerate Siwalik fauna types (Lower, Middle, Upper) with their characteristic mammals and palaeoecological settings; for (b), define fossil precisely and list six index fossils with their stratigraphic ages; for (c), describe Krol Formation's lithology (purple/green shales, limestones, dolomites), its Precambrian-Cambrian boundary significance and shallow marine environment; for (d), discuss porosity, permeability and specific yield with rock-type examples; for (e), enumerate engineering properties (compressive strength, durability, specific gravity) linking to Indian building stones like Kota stone or Makrana marble. Maintain strict word discipline—no introduction or conclusion needed for short answers.
Key points expected
- (a) Enumerates three Siwalik subdivisions (Lower, Middle, Upper) with representative fauna: Lower Siwalik (Giraffidae, Anthracotheriidae), Middle Siwalik (Elephantidae, Suidae, Bovidae), Upper Siwalik (Equidae, advanced Bovidae); links each to shifting woodland-savanna-grassland palaeoenvironments and Himalayan uplift chronology
- (b) Defines fossil as remains/traces of prehistoric organisms preserved in rock; provides two index fossils per era: Palaeozoic (Trilobites like Olenellus-Cambrian, Fusulina-Permian), Mesozoic (Ammonites like Phylloceras-Jurassic, Baculites-Cretaceous), Cenozoic (Nummulites-Eocene, Globorotalia-Pliocene) with precise stratigraphic ages
- (c) Describes Krol Formation lithology: purple-green shales, flaggy sandstones, stromatolitic dolomites, pink limestones with 'Pipe Rock' structures; identifies Terminal Proterozoic (Ediacaran) to Early Cambrian age; interprets shallow marine shelf-lagoonal environment with algal mat communities
- (d) Discusses primary/secondary porosity, permeability (intrinsic vs. hydraulic), specific yield and retention; contrasts water-bearing properties: unconfined aquifers in weathered basalts (Deccan Traps) vs. confined aquifers in Ganga basin sandstones
- (e) Enumerates engineering properties: unconfined compressive strength (>100 MPa for good building stone), specific gravity, water absorption (<1%), durability (SLA test), hardness; cites Indian examples: Kota stone, Makrana marble, Chunar sandstone, Agra red sandstone
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 25% | 12.5 | Demonstrates precise taxonomic identification for (a) with correct stratigraphic ranges; defines fossil accurately in (b) with correct index fossil-epoch pairings; correctly identifies Krol as Precambrian-Cambrian boundary formation in (c); accurately distinguishes porosity types and aquifer classifications in (d); cites correct IS standards for engineering properties in (e) | Identifies major fauna groups but confuses Siwalik subdivisions; defines fossil adequately but mixes index fossil ages or omits one era; describes Krol lithology but confuses age; discusses water properties generically without rock-specific examples; lists engineering properties without quantitative thresholds | Confuses Siwalik fauna with Gondwana or Siwalik stratigraphy; defines fossil incorrectly or provides non-index fossils; misidentifies Krol as Paleozoic or younger; conflates porosity with permeability; lists irrelevant properties like colour or texture as engineering properties |
| Diagram / cross-section | 15% | 7.5 | Includes annotated sketch for (a) showing Siwalik stratigraphic column with fauna zones; for (c) draws Krol lithostratigraphic log showing stromatolite structures; for (d) illustrates porosity-permeability relationship graph; diagrams are neat, labelled and integrated with text | Mentions diagrams but provides incomplete sketches or poorly labelled figures; draws generic stratigraphic column without fauna indicators; shows basic porosity diagram without rock-type differentiation | No diagrams attempted despite visual opportunities; or draws irrelevant diagrams (e.g., fossil sketches instead of stratigraphic columns); diagrams contradict textual description |
| Field evidence | 20% | 10 | Cites specific type localities: (a) Pinjor, Tatrot, Dhok Pathan formations; (b) specific fossil sites like Spiti (trilobites), Kutch (ammonites), Assam (Nummulites); (c) Krol belt exposure in Mussoorie-Simla Himalaya; (d) field examples from CGWB aquifer maps; (e) quarry sites like Ramganjmandi (Kota stone), Makrana | Mentions general Himalayan region for Siwalik; identifies fossil eras without specific Indian localities; knows Krol is in Himalaya but not specific area; gives generic aquifer examples; names building stones without quarry locations | No field localities cited; invents non-existent sites; confuses Siwalik with Vindhyan or other formations; attributes marine fossils to terrestrial settings; no Indian examples for building stones |
| Quantitative reasoning | 20% | 10 | Provides numerical data: (a) approximate ages for Siwalik subdivisions (Upper: 2.5-0.6 Ma); (b) precise stratigraphic ages in Ma for index fossils; (c) Krol age ~540-600 Ma; (d) porosity percentages for different rocks, specific yield values; (e) UCS values, water absorption %, specific gravity ranges for Indian building stones | Gives approximate geological ages (epoch-level); mentions porosity/permeability as high/medium/low without numbers; states building stones are 'strong' or 'durable' without quantitative thresholds | No numerical data; grossly incorrect ages (e.g., Siwalik as Paleozoic); confuses qualitative descriptors; invents unrealistic engineering values |
| Indian / economic relevance | 20% | 10 | Demonstrates economic significance: (a) Siwalik vertebrate fossils for biostratigraphy and hydrocarbon exploration in Himalayan foreland basin; (b) index fossils for Indian basin correlation and oil exploration; (c) Krol as potential hydrocarbon source rock and Cambrian boundary GSSP significance; (d) groundwater exploitation statistics for Indian aquifers; (e) specific Indian building stone industry value, export potential, heritage conservation (Taj Mahal) | Mentions general economic importance without specifics; notes fossils are 'useful for dating'; states Krol is 'important'; discusses groundwater abstractly; lists building stones without economic context | No economic or Indian relevance discussed; treats topics as purely academic; ignores commercial building stone industry; no mention of groundwater crisis or hydrocarbon potential |
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