Daily Current Affairs Quiz: September 09, 2025

Answer: C [Statement-I is correct but Statement-II is incorrect]
Explanation:

Statement 1 is correct:  It accurately describes the rock cycle, which is a continuous process involving the transformation of rocks from one type to another.

Statement 2 is incorrect: Sedimentary rocks are formed through the deposition, compaction, and cementation of mineral and organic particles, not from the cooling and solidification of magma or lava, which leads to the formation of igneous rocks.

Answer: B [Accretion of planetesimals followed by internal radioactive heating and partial melting leading to density stratification.]
Explanation:

a is incorrect: Gravitational compression did contribute to the Earth’s heating, but it would lead to a denser core and less dense outer layers, not a uniform distribution.

b is Correct: The Earth formed through the accretion of planetesimals. Radioactive decay and impact energy heated the early Earth, causing widespread melting. This allowed denser elements (iron, nickel) to sink and form the core, while lighter elements rose to form the mantle and crust (density stratification).

c is incorrect: While large impacts played a role in Earth’s early history, fragmentation and re-assembly based on size were not the primary drivers of core-mantle-crust differentiation.

d is incorrect: Volcanism contributed to crust formation later in Earth’s history. But the primary differentiation had already occurred due to melting and density stratification. Volcanism is a consequence of differentiation, not the cause.

Answer: D [3 and 4 only]
Explanation:

Statement 1 is correct: Foliation is a characteristic feature of metamorphic rocks formed under directed pressure, leading to the parallel alignment of platy or elongated minerals.

Statement 2 is correct: Non-foliated rocks lack this layered structure and typically form where the pressure during metamorphism is uniform, or the parent rock lacks minerals with a preferred orientation.

Statement 3 is incorrect: Marble is a non-foliated metamorphic rock formed from limestone or dolostone. Its granular texture lacks distinct layers or bands.

Statement 4 is incorrect: Gneiss is a high-grade foliated metamorphic rock. It displays a characteristic banded texture due to the segregation of light and dark-colored minerals.

Answer: C [1, 2, 3 and 4 only]
Explanation:

Statement 1 is correct: Metamorphic rocks are formed when pre-existing rocks (protoliths) are transformed by heat, pressure, and/or chemically active fluids.

Statement 2 is correct: Metamorphism involves transformation in the solid state. If the rock melts, it becomes igneous upon cooling.

Statement 3 is correct:  The original rock can be any type – igneous, sedimentary, or even another metamorphic rock.

Statement 4 is correct: Marble (from limestone or dolostone), slate (from shale), and quartzite (from sandstone) are common examples of metamorphic rocks.

Statement 5 is incorrect: While metamorphism often destroys fossils, some metamorphic rocks derived from sedimentary rocks may still contain distorted or partially obliterated fossils.

Answer: B [Rift valleys are primarily formed by down warping between parallel faults, often associated with volcanic activity and graben structures.]
Explanation:

a is incorrect: While glacial erosion can create U-shaped valleys, rift valleys are formed tectonically.

b is correct: Rift valleys are formed by the divergence of tectonic plates and subsequent downwarping between parallel faults. This process often leads to volcanic activity and the formation of graben (down-dropped blocks). The East African Rift Valley is a prime example.

c is incorrect: Synclinal folds are indeed downfolds in rock strata, but they are a different geological feature than rift valleys, which are formed by faulting.

d is incorrect: While meandering rivers create features like floodplains and oxbow lakes through lateral erosion, rift valleys are formed by tectonic processes.