Question

Match the type of rock with its metamorphic form.

Igneous/Sedimentary rock	Metamorphic rock
(P) Shale	(1) Gneiss
(Q) Limestone	(2) Quartzite
(R) Granite	(3) Marble
(S) Sandstone	(4) Slate

• A. P \(\rightarrow\) 4, Q \(\rightarrow\) 3, R \(\rightarrow\) 1, S \(\rightarrow\) 2
• B. P \(\rightarrow\) 3, Q \(\rightarrow\) 1, R \(\rightarrow\) 4, S \(\rightarrow\) 2
• C. P \(\rightarrow\) 4, Q \(\rightarrow\) 3, R \(\rightarrow\) 2, S \(\rightarrow\) 1
• D. P \(\rightarrow\) 3, Q \(\rightarrow\) 4, R \(\rightarrow\) 2, S \(\rightarrow\) 1

Hint:

Think about what each parent rock turns into under contact or regional metamorphism.

Answer 1

The Correct Option is A

This question can also be solved by starting from the four metamorphic rocks and asking what parent rock each one forms from, instead of starting from the parent rocks.

1. Gneiss: a coarse grained rock with visible light and dark mineral banding, produced by strong regional metamorphism of a quartz and feldspar rich igneous rock. Among the choices, that parent is granite (R), so Gneiss (1) pairs with R.
2. Quartzite: an extremely hard, glassy rock made almost entirely of interlocked quartz grains. It forms only from a quartz rich sedimentary rock, which here is sandstone (S), so Quartzite (2) pairs with S.
3. Marble: a rock made of interlocking calcite or dolomite crystals, formed when limestone (Q) recrystallises under heat, so Marble (3) pairs with Q.
4. Slate: a fine grained, easily split rock formed at the lowest metamorphic grade from a clay rich sedimentary rock, which is shale (P), so Slate (4) pairs with P.

Putting the four pairs together gives P to 4, Q to 3, R to 1 and S to 2, which is option (A).

Let's summarize:

• Granite (igneous, quartz and feldspar rich) becomes gneiss under strong metamorphism.
• Sandstone (quartz sand) becomes quartzite; limestone (calcite) becomes marble; shale (clay) becomes slate.

So the correct match is option (A): P to 4, Q to 3, R to 1, S to 2.