Final answer:
The presence of limestone in a succession of rock layers indicates that the area most likely was once a portion of continental crust submerged by warm shallow seawater.
Step-by-step explanation:
The presence of limestone in a succession of rock layers indicates that the area most likely was once a portion of continental crust submerged by warm shallow seawater. Limestone is a sedimentary rock that forms from the accumulation of the remains of marine organisms such as clams and corals. It is commonly found in areas that were once covered by shallow seas. Fossils, such as shell fragments and coral chips, are often found in limestone, further supporting its formation in a marine environment.