The DeSoto plain was the ancient feature of Florida as the peninsula formed over time. Edward Petuch writes that the DeSoto plain had rivers which poured sediments into the Polk Subsea during the Miocene's Serravallian and early Langhian stages filling the Okeechobean Basin to the south.[2] A large complex river delta was formed between the time of the Polk Subsea and the creation of the Charlotte Subsea called the DeSoto Delta. This delta continued to carry sediments from a paleovalley on the DeSoto Plain and Lake Wales Ridge system region to the basin's western side. (Petuch, p. 50)
