Question

Match the primary sedimentary structure in Group I with the corresponding process of formation in Group II. 
\[\begin{array}{|l|l|} \hline \textbf{Group I} & \textbf{Group II} \\ \hline \text{P. Asymmetric ripples} & \text{1. Water escape} \\ \hline \text{Q. Dish and pillar} & \text{2. Bed load transportation of sediments} \\ \hline \text{R. Flute cast} & \text{3. Deposition from alternate traction and suspension load} \\ \hline \text{S. Wavy bedding} & \text{4. Scouring by turbulent eddy} \\ \hline \end{array}\]

• A. P-1, Q-2, R-3, S-4
• B. P-2, Q-3, R-1, S-4
• C. P-1, Q-4, R-3, S-2
• D. P-2, Q-4, R-1, S-3

Hint:

Sedimentary structures such as ripples, bedding, and flute casts are key indicators of past environmental conditions and sediment transport mechanisms.

Answer 1

The Correct Option is B

Step 1: Analysis of each structure:

P. Asymmetric ripples: Formed by Bed load transportation of sediments (2)

• Asymmetric (current) ripples form when sediment grains move along the bed by traction and saltation under unidirectional current
• The asymmetry indicates flow direction

Q. Dish and pillar structures: Formed by Water escape (1)

• These are soft-sediment deformation structures created when pore water escapes upward through rapidly deposited sediments
• Dish structures are concave-up laminae, pillars are vertical escape conduits

R. Flute cast: Formed by Scouring by turbulent eddy (4)

• Flute casts are preserved scour marks on the base of beds
• Created by turbulent eddies eroding the underlying sediment
• The bulbous end points upstream

S. Wavy bedding: Formed by Deposition from alternate traction and suspension load (3)

• Wavy bedding forms when alternating conditions favor both traction (ripples/laminae) and suspension deposition (mud drapes)
• Characteristic of environments with fluctuating current velocities

Step 2: Matching:

• P → 2 (Asymmetric ripples → Bed load transportation)
• Q → 1 (Dish and pillar → Water escape)
• R → 4 (Flute cast → Scouring by turbulent eddy)
• S → 3 (Wavy bedding → Alternate traction and suspension)

Answer: (B) P-2, Q-1, R-4, S-3