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Q161. Match the metamorphic rocks in Group I with corresponding parent rocks in Group II.
The correct answer is Amphibolite - Basalt, Khondalite - Shale, Calc-gneiss - Marl, Quartzite - Sandstone. When baked by metamorphism, Basalt turns into dark, hornblende-rich Amphibolite. Aluminum-rich Shale cooks into the garnet-sillimanite rock known as Khondalite. Marl (a mix of limestone and mud) transforms into Calc-gneiss. Finally, pure quartz Sandstone recrystallizes into solid Quartzite.
Q162. Match the minerals in Group I with corresponding characteristic properties in Group II.
The correct answer is Labradorite - Play of colors, Actinolite - Acicular habit, Fluorite - Four sets of cleavage, Barite - High specific gravity. Labradorite is famous for its iridescent labradorescence (play of colors). Actinolite typically grows in long, radiating needle-like crystals (acicular habit). Fluorite uniquely exhibits four perfect directions of octahedral cleavage. Barite is remarkably heavy for a non-metallic mineral, giving it a high specific gravity.
Q163. Match the Precambrian lithounits in Group I with corresponding cratons in Group II.
The correct answer is Kolhan Group - Singhbhum, Debari Group - Aravalli, Bababudan Group - Dharwar, Sukma Group - Bastar. In Indian stratigraphy, these are classic craton correlations. The Kolhan Group is situated in the Singhbhum Craton. The Debari Group is part of the Aravalli Supergroup. The Bababudan Group is a famous iron-bearing sequence in the Dharwar Craton. The Sukma Group represents ancient rocks in the Bastar Craton.
Q164. Match the sedimentary structures in Group I with the corresponding processes in Group II.
The correct answer is Stromatolite - Biostratification, Flute cast - Erosion, Mud crack - Desiccation, Dish and pillar - Liquefaction. Stromatolites are built layer-by-layer by living microbe mats (biostratification). Flute casts are gouged out by swirling, erosive water currents. Mud cracks form when wet mud dries up and shrinks in the sun (desiccation). Dish and pillar structures happen when water gets rapidly squeezed out of soft sand, liquefying it as it escapes upwards.
Q165. On a geological map of a flat area, the plunge direction of an antiformal anticline is
The correct answer is towards the fold closure. An 'antiformal anticline' is a rock folded upward like an arch. When this tilted arch intersects flat ground, it creates a U-shaped or V-shaped pattern on a map. Because the arch plunges downwards into the earth, the tip of the V-shape (the fold closure) physically points exactly in the direction the fold is plunging underground. Pointing 'away' would describe a bowl-shaped syncline.
Q166. Permian is a/an
The correct answer is Period. Geologists divide all of Earth's history into a calendar called the Geologic Time Scale. The largest chunks of time are Eons, which are divided into Eras, which are further sliced into 'Periods', and finally into tiny Epochs. The 'Permian' is a specific, well-known geological 'Period' fitting inside the Paleozoic Era.
Q167. Polymorphic minerals have
The correct answer is different crystal forms and identical composition. In mineralogy, 'polymorphism' means 'many forms'. It occurs when the exact same chemical ingredients (identical composition) crystallize into completely different structural shapes (different crystal forms) due to varying heat and pressure—for example, carbon forming both diamond and graphite. The other options describe solid solutions or entirely unrelated minerals.
Q168. Shear waves do not travel through the
The correct answer is outer core. Shear waves (S-waves) are transverse seismic waves that can only propagate through solid materials. Because the Earth's outer core is entirely composed of liquid iron and nickel, S-waves completely fail to travel through it. They easily pass through the solid upper continental crust, upper mantle, and lower mantle.
Q169. Turbidites commonly form in
The correct answer is deep marine environment. Turbidites are sedimentary rocks formed by massive underwater avalanches (turbidity currents) that rush down the continental slope and deposit sediment on the deep ocean floor. Fluvial (rivers), tidal flats, and beach environments are extremely shallow or terrestrial settings that do not experience these deep-sea underwater avalanches.
Q170. Which of the following are the characteristics of a typical porphyry copper deposit? I. Associated with granitic rocks II. Low-grade and high tonnage of ore III. Presence of alteration zones IV. Occurrence in convergent tectonic setting
Porphyry copper deposits are massive. They are formed from hot fluids separating from cooling granitic/porphyritic magmas (I). Because the copper is scattered throughout the entire rock mass, the ore is notoriously low-grade but incredibly huge in volume (high tonnage) (II). The boiling fluids intensely bake and alter the surrounding host rocks (alteration zones) (III). They almost exclusively form above subduction zones at convergent plate boundaries (IV).