Everglades Pseudoatoll

The Everglades Pseudoatoll (also called a pseudo-atoll) was a major geomorphic feature of southern Florida during the Pliocene epoch.

The Everglades Pseudoatoll began its growth during the early Eocene as a paleodepression possibly created by an asteroid impact upon the carbonate Florida Platform at the southern part of the Everglades National Park. The pseudo-atoll is surrounded by a raised rim. Its growth as a reef system and pseudo-atoll began during the Oligocene reaching its maximum size of 330 km (210 mi) north to south during the Piacenzian of the late Pliocene. (Petuch, 163).

The Everglades Pseudoatoll was a U-shaped asymmetrical system of reefs that surrounded the Okeechobean Sea, not unlike South Pacific atolls surrounded by a central lagoon. The west side was more developed than the east and south, as was the remainder of the west side.

On the western side of this pseudo-atoll lay the Immokalee Reef Tract and chain of islands called the Immokalee Archipelago. The large Hendry Platform lay behind the reef on the east. Mangrove forests extended southwesterly of the pseudoatoll along what would be the southwestern Florida coast. To the northwest was the Myakka Lagoon System, a tropical estuary of brackish water.

On the east the lay the Miami-Palm Beach Reef Tract with narrow back reef. Between the west and east was the wide and very deep 100 meter (330 feet) lagoon known as the Loxahatchee Trough. The northern part of the pseudo-atoll was the Kissimmee Embayment which was lined with mud flats and jungles of mangrove.

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