Sea-floor sediments would be the most useful in studying Florida's fossil record. The reason for this is that Florida was submerged in water during several periods in its geological history, and sea-floor sediments would have accumulated and preserved any fossils that were present during those times. These sediments would contain evidence of marine life, such as shells and other biotic remains, as well as information about the environment and conditions in which they lived.
In contrast, wood is not typically well-preserved in underwater environments, as it is more susceptible to decay and destruction by wood-boring organisms. Ice, on the other hand, is not likely to have been present in Florida during periods of submergence, and thus would not provide information about Florida's fossil record during those times.
Therefore, sea-floor sediments are the most useful material for studying Florida's fossil record, as they have the potential to provide the most complete and informative picture of Florida's ancient life and environments