Question

In an angular unconformity, the younger strata are oriented as:

• A. dipping 45°
• B. dipping 60°
• C. inclined
• D. horizontal

Hint:

Younger layers in angular unconformities are horizontal; older layers are tilted.

Answer 1

The Correct Option is D

To determine how younger strata are oriented in an angular unconformity, we analyze the geological definition and compare the given options.

1. Understanding Angular Unconformity:
An angular unconformity is a type of geological discontinuity where:
- Older strata are tilted or folded due to tectonic forces.
- Younger strata are deposited horizontally on top of the eroded surface of the older tilted layers.

2. Evaluating the Options:
- Option 1 (dipping 45°): Incorrect (younger strata are not typically at a fixed angle).
- Option 2 (dipping 60°): Incorrect (same issue as Option 1).
- Option 3 (inclined): Incorrect (younger strata are not inclined unless later deformed).
- Option 4 (horizontal): Correct (younger strata are deposited horizontally over the eroded tilted layers).

3. Conclusion:
By definition, younger strata in an angular unconformity are deposited horizontally after erosion of the older tilted layers.

Final Answer:
The correct orientation is \( \boxed{\text{horizontal}} \).