Which one of the following sedimentary structure does not mark the top surface of a bed?

Yes, current scour the top of the bed and create moulds. Flute casts are the cast structure form from these moulds and form at the bottom of the beds. For more details, look at the...

Mud cracks are formed as a result of dessication and exposure to the continental conditions. Mud cracks form at the top of the bed. Similarly, rain prints are formed by exposure of...

Flute cast forms at the bottom of the bed as a result of current scouring. Current ripple, Rain print and Mud cracks for at the top surface of a bed.