UPHESC Assistant Professor Geology PYQs

Concept: Pangaea began to break up in the Early Jurassic, about 200 million years ago, with rifting of the Central Atlantic (CAMP volcanism ~201 Ma).

1. Gondwana–Laurasia separation followed; India left Gondwana ~130 Ma and collided with Asia ~50 Ma.
2. 300–250 Ma is when Pangaea was assembled, not when drift began.

Short trick: Pangaea assembled ~300 Ma, broke ~200 Ma.

Concept: Tehri Dam (260.5 m, Uttarakhand) is an earth-and-rockfill dam with a clay core, not a concrete dam.

1. (B) True – it rests on Chandpur Formation phyllites (Garhwal Group).
2. (C) True – Lesser Himalaya, seismic zone IV/V, near the MCT and 'central seismic gap'.
3. (D) True – built on the Bhagirathi, just below its confluence with the Bhilangana.

Short trick: Tehri = tallest rockfill dam of India on phyllites – not concrete (Bhakra is concrete).

Concept: GIS uses two basic data models: raster (grid of cells/pixels, e.g. satellite images, DEMs) and vector (points, lines, polygons with coordinates).

1. Raster suits continuous data (elevation, rainfall).
2. Vector suits discrete features (wells, roads, boundaries).

Short trick: GIS = Raster (cells) + Vector (points-lines-polygons).

Concept: The greenhouse effect: short-wave solar radiation passes through the atmosphere, but the long-wave infrared (terrestrial) radiation emitted by Earth is absorbed and re-radiated by tropospheric greenhouse gases (CO₂, H₂O vapour, CH₄, N₂O).

1. CO₂ is largely transparent to incoming solar radiation.
2. UV absorption by stratospheric ozone warms the stratosphere, not the surface – it is the ozone shield, not global warming.

Short trick: Sun in (short-wave) → Earth out (long-wave IR) → trapped by tropospheric GHGs.

Concept: Intensity is a measure of the observed effects of shaking at a place (damage, human perception) and is expressed on the Modified Mercalli (MM) scale, I to XII (also MSK-64 in India).

1. Richter scale measures magnitude – the energy released at the source (logarithmic).
2. Depth of focus is a location parameter, not a measure of intensity.

Short trick: Magnitude – Richter (one value); Intensity – Mercalli (varies with place).

Concept: Cut-and-cover is a method of building shallow tunnels: a trench is excavated from the surface, the tunnel structure is built in it and then covered and the surface restored – used for metro stations, subways and utility tunnels.

1. Deep or rock tunnels use drill-and-blast, TBM or NATM instead.
2. Bridges, dams and hill roads use other construction methods.

Short trick: Cut the ground, build the box, cover it – shallow tunnels/metros.

Concept: Rocks are much weaker in tension than in compression: tensile strength is roughly 1/10 to 1/20 of uniaxial compressive strength (UCS).

1. Point load index Is(50) ≈ UCS/20–25, i.e. less than UCS.
2. Cohesion (c) in the Mohr–Coulomb criterion is also well below UCS (UCS = 2c·cosφ/(1−sinφ)).

Short trick: Rock: Compression ≫ Tension (≈10×).

Concept: Deccan Trap volcanism began in the Late Cretaceous (end of the Mesozoic, ~67–66 Ma) and continued into the early Palaeocene, coinciding with the K–Pg extinction; it is linked to the Réunion hotspot.

1. Lameta beds (Maastrichtian) and intertrappean beds with dinosaur remains date it.
2. End-Triassic → CAMP; end-Palaeozoic → Siberian Traps.

Short trick: Deccan Traps = K–T boundary, ~66 Ma.

Concept: Greenschist facies spans roughly 300–500 °C at about 0.2–1.0 GPa, so 400 °C and 0.6–0.7 GPa (≈20–25 km depth) fall in it.

1. Zeolite facies: below ~250 °C, low pressure.
2. Amphibolite facies: above ~500–550 °C.
3. Pyroxene hornfels: very high T (>650 °C) at very low P (contact aureoles).

Short trick: Zeolite <250 °C → Greenschist 300–500 °C → Amphibolite 500–700 °C → Granulite >700 °C.

Concept: At high grade, hydrous minerals break down by 'dehydration (fluid-absent) melting': e.g. biotite + plagioclase + quartz → garnet/orthopyroxene + K-feldspar + melt. The H₂O from biotite goes into the melt – the rock is dehydrated.

1. Muscovite melts first (~650–700 °C), biotite at ~800–850 °C, leaving anhydrous granulite residues.
2. This is the path from amphibolite to granulite facies – not cooling, hydration or uplift.

Short trick: Biotite melting = water out of the rock → dry granulite residue.

Concept: Karst develops by solution of limestone/dolomite; sinkholes (dolines) are the most diagnostic karst landform, along with uvalas, poljes, caves, lapies and disappearing streams.

1. Artesian wells – confined aquifers under pressure; not specific to karst.
2. Cone of depression – lowering of water table around a pumped well.

Short trick: Karst = sinkholes + caves (solution of limestone).

Concept: A prograding delta builds a coarsening-upward sequence: prodelta muds → delta-front silts and sands → distributary-mouth-bar and channel sands at the top.

1. Fluvial (meandering) channel deposits are typically fining-upward (point bar).
2. Lacustrine and aeolian deposits have no characteristic coarsening-upward trend.

Short trick: Delta progrades → coarsening up; river point bar → fining up.

Concept: Pyrometamorphism is the extreme-temperature, very-low-pressure variety of contact metamorphism seen in xenoliths within lavas or shallow intrusions, sometimes with partial melting (buchites, sanidinite facies).

1. Metasomatism – change in bulk chemistry by fluids.
2. Dynamic metamorphism – deformation in fault/shear zones (mylonites).
3. Impact metamorphism – meteorite shock (very high P and T, instantaneous).

Short trick: Pyro = fire: xenolith baked in lava → sanidinite facies.

Concept: Fred Hoyle (1960) explained the Sun's slow rotation through magnetic coupling: the Sun's magnetic field transferred angular momentum to the surrounding nebular disc from which the planets formed – hence the 'magnetic theory'.

1. Moulton & Chamberlin (1905) – planetesimal hypothesis.
2. Kant (1755) & Laplace (1796) – nebular hypothesis.
3. G. P. Kuiper (1951) – protoplanet hypothesis.

Short trick: Hoyle → magnetic braking; Kant–Laplace → nebula; Chamberlin → planetesimals; Kuiper → protoplanets.

Concept: A 'living fossil' is a living organism that closely resembles relatives known only from the fossil record and has changed little over a very long time. As printed, every option is a textbook living fossil, so no single answer can be chosen.

1. Ginkgo biloba – sole survivor of the Ginkgoales (Permian/Jurassic lineage).
2. Neopilina (spelt 'Neophilina') – monoplacophoran mollusc, group thought extinct since the Devonian, found alive in 1952.
3. Sphenodon (tuatara) – sole surviving rhynchocephalian (Triassic group).
4. Opossum (Didelphis) – marsupial little changed since the Cretaceous, also often called a living fossil.

Short trick: Classic living fossils: Ginkgo, Neopilina, Sphenodon, Latimeria, Limulus, Lingula.

Concept: Graptolites range from the Middle Cambrian to the Carboniferous: planktonic graptoloids died out in the Early Devonian, but the sessile dendroid graptolites (e.g. Dictyonema) survived into the Carboniferous (Mississippian), when the group became extinct.

1. Ordovician–Silurian is their acme (zone fossils).
2. No graptolites are known from the Triassic.

Short trick: Graptolites: Cambrian → Carboniferous; peak Ordovician–Silurian.

Concept: In a soil profile the A horizon is the topsoil – the dark, humus-rich mineral surface layer where most biological activity and eluviation occur.

1. O horizon – loose organic litter (leaves, humus) lying above the mineral soil; not counted as topsoil proper.
2. B horizon – subsoil, zone of illuviation (clay, Fe, Al accumulate).
3. C – weathered parent material; R – bedrock.

Short trick: O-A-B-C-R: Organic litter, topsoil (A), suBsoil (B).

Concept: Mid-ocean ridges (divergent), trenches (convergent) and transform faults (conservative) are, by definition, plate boundaries. Ordinary strike-slip faults are common within plates (intraplate faults) and need not mark a plate boundary.

1. Every transform fault is a strike-slip fault, but not every strike-slip fault is a transform plate boundary.
2. Example: many strike-slip faults within continents (e.g. in the Indian shield) are intraplate.

Short trick: All transforms are strike-slip; not all strike-slip faults are transforms.

Concept: In a similar fold (Ramsay class 2) every folded surface has the same shape, so the thickness measured parallel to the axial plane (axial-plane thickness) is constant, while orthogonal thickness is greater in the hinge and thinner on the limbs.

1. (A) and (B) describe parallel (concentric) folds – constant orthogonal thickness, common centre of curvature.
2. (D) is reversed – similar folds thicken in hinges and thin on limbs.

Short trick: Similar fold: same shape, constant axial-plane thickness, thick hinges.

Concept: W. M. Davis (1899) defined the cycle of erosion (geographical cycle) as the sequence of landscape evolution – youth, maturity and old age – from rapid uplift down to a peneplain, controlled by structure, process and stage.

1. Uplift is only the starting condition; erosion–deposition are the processes, not the cycle itself.
2. It describes how landforms change systematically with time.

Short trick: Davis: Structure–Process–Stage → youth → maturity → old age (peneplain).