The Florida Middle Ground is a deep-water coral reef on the outer continental shelf in the northeastern Gulf of Mexico. The reef consists of two parallel north-trending ridges, each about 50 km long and rising 11 m from the shelf to a depth of about 26 m. The ridges are separated by a broad, flat, sediment-filled valley about 8 km wide. The south end of the valley is partly occluded by irregular knolls. Station data (in transects) were collected over several seasons by Shipek grab, scuba team, and manned submersible. Detailed textural and constituent analyses of valley sediments reveal sandsized carbonate material unlike the finer sands and silts found on the adjacent continental shelf. The percentage of terrigenous material in the valley is substantially less than that o the surrounding shelf.

Hurricanes, frequent storm fronts, the Gulf Loop Current, and semidiurnal tidal currents together comminute and erode ridge constituents. Those constituents transported between the ridges are mixed and trapped with shelf sediments. An accumulation of up to 5 m of sediment, over twice the thickness on the adjacent shelf, is ponded in the valley.

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