Identify the correct sequence of regional metamorphosis of shale. (A) Slate (B) Schist (C) Phyllite (D) Gneiss
Choose the correct answer from the options given below:

Correct option is D

Explanation:
Shale, a sedimentary rock, undergoes regional metamorphism under increasing temperature and pressure conditions. The transformation proceeds in a progressive metamorphic sequence. The typical order of increasing metamorphism is: Shale → Slate → Phyllite → Schist → Gneiss
· Slate forms first from low-grade metamorphism.
· Phyllite follows with a slightly higher grade.
· Schist forms at medium-grade metamorphism.
· Gneiss is the product of high-grade metamorphism.
Information Booster:
Regional metamorphism occurs over large areas and is typically associated with mountain-building processes. As pressure and temperature increase, fine-grained sedimentary rocks like shale progressively transform into foliated metamorphic rocks. Foliation becomes more pronounced at each successive stage, with mineral alignment and recrystallization increasing from slate to gneiss.
Additional Information:
· Option (1) is incorrect because it suggests Schist forms directly after Slate, skipping Phyllite.
· Option (2) is incorrect as it places Schist before Slate and ends with Phyllite, which is not the highest-grade rock.
· Option (3) is incorrect because it shows a reverse metamorphic sequence.
· Only Option (4) correctly reflects the increasing metamorphic grade: Slate → Phyllite → Schist → Gneiss.