Which process is most likely responsible for the removal of the missing parts of the rock layers

I believe Erosion is the process most likely responsible for the removal of the missing parts of the rock layers. Erosion involves the physical action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust, then  moved away to another location. 

I’d have to say no because without oxygen in the water the fish would all be dead. so if you want to fish for dead fish, pick the ponds with the lowest oxygen concentrations.