UPHESC Assistant Professor Geology PYQs

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).

Concept: Compression shortens and thickens the crust through folding and thrust (reverse) faulting, as in fold-and-thrust belts like the Himalaya.

1. Normal faulting – crustal extension (lengthening).
2. Strike-slip faulting – horizontal displacement with no net shortening.
3. Metamorphism is a change in mineralogy/texture, not a shortening mechanism.

Short trick: Squeeze → folds + thrusts; Stretch → normal faults.

Concept: Poisson's ratio ν = lateral strain / longitudinal strain (dimensionless; about 0.25 for most rocks, 0.5 for incompressible fluids).

1. Young's modulus E = longitudinal stress / longitudinal strain.
2. Bulk modulus K = pressure / volumetric strain.
3. Rigidity (shear) modulus G = shear stress / shear strain.

Short trick: Poisson = sideways ÷ lengthwise strain.

Concept: Each stage of the fluvial cycle has typical landforms.

1. Initial stage – vigorous down-cutting into bedrock by eddies with pebbles: pot holes → (3).
2. Youth – deep V-shaped valleys, gorges → (2).
3. Mature – where the river leaves the mountains onto the plains, its load spreads as alluvial fans → (1).
4. Old stage – broad flood plains, meanders, ox-bow lakes → (4). Code 3-2-1-4.

Short trick: Pothole → V-valley → fan → flood plain (mountain to plain).

Concept: After the elastic straight line (1) and the yield point, the curve can follow three paths: horizontal (3) = ideal plastic flow, rising (4) = strain hardening (more stress needed for more strain), falling (2) = strain softening (stress needed drops as strain increases).

1. Sector 2 slopes downward beyond yield – the rock weakens with continued strain → strain softening.
2. Sector 1 – elastic; sector 3 – perfectly plastic; sector 4 – strain hardening.

Short trick: After yield: up = hardening, flat = plastic, down = softening.

Concept: Driven by the trade winds and westerlies and deflected to the right by the Coriolis force, the major subtropical ocean gyres circulate clockwise in the Northern Hemisphere and anticlockwise in the Southern Hemisphere.

1. N. Atlantic gyre: Gulf Stream → N. Atlantic Drift → Canary → N. Equatorial current (clockwise).
2. N. Pacific: Kuroshio → N. Pacific → California → N. Equatorial (clockwise).

Short trick: North – Coriolis to the right – clockwise gyres.

Concept: Barrier reefs, separated from the coast by a wide, deep lagoon, are the largest, highest and most extensive of all reef types; the Great Barrier Reef of Australia extends ~2300 km.

1. Fringing reefs – narrow reefs attached to the shore; most common but small.
2. Atolls – ring-shaped reefs around a lagoon, no central island (e.g. Lakshadweep).

Short trick: Great Barrier Reef = the biggest reef = barrier type.

Concept: Thermohaline ('thermo' = heat, 'haline' = salt) circulation is the global deep-ocean 'conveyor belt' driven by density differences caused by temperature and salinity.

1. Cold, salty water sinks in the North Atlantic and around Antarctica, flows along the deep ocean and upwells elsewhere.
2. Surface currents are mainly wind-driven, not thermohaline.

Short trick: Thermo + haline = temperature + salt → density-driven deep currents.

Concept: Fine terrigenous (wind- and current-borne) clay settles on the abyssal floor extremely slowly – of the order of 1–2 mm per 1000 years (pelagic red/brown clay).

1. Biogenic oozes accumulate faster, ~1–3 cm/1000 yr.
2. mm/year rates are typical of continental shelves, deltas and lakes – far too fast for the deep ocean.

Short trick: Deep-sea clay: about a millimetre per millennium.

Concept: A broad belt of siliceous diatom ooze encircles Antarctica (Southern Ocean) and also occurs in the high-latitude North Pacific, where cold, nutrient-rich upwelling waters support diatom blooms.

1. Radiolarian ooze – mainly the equatorial Pacific.
2. Carbonate (Globigerina) ooze – warm, shallower (above CCD) floors of the Atlantic; carbonate dissolves in cold Antarctic waters.

Short trick: Diatoms – cold poles; Radiolaria – equator; Globigerina – warm, above CCD.

Concept: In a confined aquifer, water in a well rises to the piezometric (potentiometric) surface; where this surface lies above ground level, water flows out at the surface without pumping – a flowing artesian well.

1. If the piezometric surface is above the aquifer top but below ground → non-flowing artesian well.
2. Classic example: Great Artesian Basin, Australia.

Short trick: Piezometric surface above ground = free-flowing artesian well.