UPHESC Assistant Professor Geology PYQs

Concept: Goldschmidt grouped elements by the phase they prefer in a differentiated Earth/meteorite.

1. Siderophile ('iron-loving': Fe, Ni, Co, Pt, Au) – metallic iron phase → (3).
2. Chalcophile ('copper/sulphur-loving': Cu, Zn, Pb, Ag) – sulphides → (1).
3. Lithophile ('rock-loving': Na, K, Mg, Al, Si) – silicates → (2).
4. Atmophile (N, noble gases, H) – atmosphere → (4). Code: 3-1-2-4.

Short trick: Sidero = iron, Chalco = sulphide, Litho = silicate, Atmo = air.

Concept: In a ductile shear zone strain is heterogeneous: it increases from the margins (low strain, protomylonite) to a maximum at the centre (ultramylonite), which is why foliation curves (sigmoidally) into the zone.

1. (A) True – faults pass downward into ductile shear zones below the brittle–ductile transition.
2. (C) True – from mm-scale to crustal-scale (hundreds of km).
3. (D) True – displacement is accommodated by ductile flow.

Short trick: Shear zone: strain is low at edges, highest in the core – never uniform.

Concept: Pull-apart basins are rhomb-shaped depressions formed at releasing bends or releasing step-overs between en-echelon strike-slip fault segments, where local extension (transtension) occurs.

1. Examples: Dead Sea basin, Death Valley, Salton trough.
2. Restraining bends in the same systems give push-up ridges (compression).

Short trick: Releasing bend → pull-apart; restraining bend → push-up.

Concept: Darcy's law: discharge through a porous medium Q = KiA, where K = hydraulic conductivity, i = hydraulic gradient (dh/dl), A = cross-sectional area.

1. Q = AV is the continuity equation (V = Darcy velocity/specific discharge = Ki).
2. Darcy (1856) derived it from sand-filter experiments at Dijon.

Short trick: Darcy: Q = K·i·A ('Quite Kind i A').

Concept: Discharge is the volume of water passing a section per unit time: Q = A × V = m² × m/s = m³/s (cumec).

1. m/s – velocity (or hydraulic conductivity).
2. m²/s – transmissivity or diffusivity.

Short trick: Discharge = volume/time → m³/s (cumec).

Concept: Typical porosities: clay 40–70%, weathered granite 34–57%, coarse sand 25–40%, but unweathered basalt only about 3–10% (higher only if vesicular/fractured).

1. Clay has the highest porosity yet very low permeability.
2. Crystalline/igneous rocks like fresh basalt have the least primary porosity.

Short trick: Fine sediments – high porosity; fresh crystalline rock – lowest.

Concept: Kimberlite is a volatile-rich (CO₂, H₂O) potassic ultrabasic rock; primary magmatic calcite (carbonate) is a characteristic groundmass mineral, so statement (C) is false.

1. (A) True – high-pressure phases like coesite occur as inclusions in kimberlitic diamonds/xenoliths.
2. (B) True – carrot-shaped diatremes (pipes) narrowing downward into root zones and dykes.
3. (D) True – kimberlite pipes are the primary source of diamonds (Kimberley, Majhgawan-Panna).

Short trick: Kimberlite = olivine + phlogopite + CALCITE (carbonate-rich), diamond-bearing pipe.

Concept: In a binary eutectic system (e.g. diopside–anorthite) the eutectic point gives the lowest temperature of crystallization/melting and the composition at which two minerals crystallize together in fixed proportion.

1. (1) It tells the order and final temperature of crystallization – correct.
2. (2) It fixes the composition/proportion of minerals crystallizing from the melt – correct.
3. (3) Crystal shape and size depend on kinetics (cooling rate, nucleation), not on the equilibrium phase diagram – incorrect.

Short trick: Phase diagram = T + composition; texture (size/shape) = kinetics.

Concept: A water-table contour (equipotential) map shows hydraulic head; groundwater – and dissolved contaminants – flow perpendicular to contours from high to low head, so flow lines drawn on it trace a pollutant back to its source and forward to its destination.

1. Porosity and permeability maps show aquifer properties but not flow direction.
2. Soil maps give only surface material.

Short trick: Flow ⟂ water-table contours, high → low head.

Concept: Slope failure occurs when driving (shear) stress exceeds shear strength; many factors combine.

1. Tectonics – active faults, earthquakes, fractured/sheared rock.
2. Slope angle – steeper slopes raise shear stress.
3. Rainfall – raises pore-water pressure, reduces effective strength (the commonest trigger in the Himalaya).

Short trick: Landslide = steep slope + weak (tectonised) rock + water trigger.

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.