Question

Which of the following sedimentary structures is/are found in intertidal deposits?

• A. Ladder-back ripple
• B. Rain print
• C. Double mud drape
• D. Mud-crack

Hint:

- Intertidal deposits often show desiccation features (mud-cracks, rain prints).
- Bidirectional tidal currents → special ripple marks (ladder-back ripples).
- Double mud drapes are more diagnostic of tidal rhythmites, not general intertidal flats.

Answer 1

The Correct Option is A, B, D

Step 1: Intertidal environment conditions.
Intertidal zones are periodically exposed and submerged due to tidal activity. Sedimentary structures here are influenced by:
- Tidal currents,
- Periodic exposure to air,
- Alternating wetting and drying,
- Rain and desiccation effects.
Step 2: Evaluating the options.
- (A) Ladder-back ripple: These form under bidirectional tidal currents, characteristic of intertidal zones.
- (B) Rain print: Raindrop impressions form when exposed tidal flats are struck by rainfall. Common in intertidal flats.
- (C) Double mud drape: These are more typical of tidal rhythmites and estuarine deposits, not characteristic of open intertidal flats.
- (D) Mud-crack: Form due to desiccation during low tide exposure in intertidal flats. Very common.
Step 3: Final Answer.
Thus, the correct set of intertidal sedimentary structures is: \[ \boxed{\text{A, B, and D are correct.}} \]