Question

Cross beds and graded beds do not occur together, because they represent:

• A. Contrasted ages
• B. Contrasted lithology
• C. Contrasted depositional conditions
• D. Both contrasted lithology and age

Hint:

Cross bedding indicates current action, while graded bedding indicates settling from suspension.

Answer 1

The Correct Option is C

Concept:
Sedimentary structures form under specific depositional conditions. Cross bedding and graded bedding represent different energy and flow conditions.

Step 1: Cross bedding.
Cross bedding forms due to migration of ripples, dunes or bars under current action. \[ \text{Cross bedding} \Rightarrow \text{traction current conditions} \]

Step 2: Graded bedding.
Graded bedding forms when particles settle from suspension, usually from a waning current. \[ \text{Graded bedding} \Rightarrow \text{settling from suspension} \]

Step 3: Compare both.
Since both structures represent different depositional environments and processes, they normally do not occur together. \[ \therefore \text{Correct Answer is (C)} \]