The formation has two distinct facies -- an eastern oolitic facies that
forms the Atlantic Coastal Ridge, and the bryozoan facies to the west,
in the Everglades. The bryozoan facies is comprised entirely of one species,
Schizoporella
floridana (Osburn 1914).
The oolitic facies can be further divided into a cross-bedded and a bioturbated facies. The stratigraphic sequence throughout the formation is alternating sections of the two facies. At the southernmost locale, Ingraham Park, the bioturbated facies is on the bottom, then a section of cross-bedding, with a final bioturbated section at the top of the formation.
The cross-bedding throughout the formation is differentially weathered. Differential weathering, or selective cementation, is visible in 2 cm couplets, with the well cemented layers being more resistant.
The limestone is composed mainly of ooids with some quartz sand and small mollusk fossils (Figure 1) . The Miami Limestone ooids are small coated carbonate grains, which contain a nucleus of either a shell fragment, or a quartz grain (Figure 2) . These small round spheres were formed by the deposition of one to five concentric layers of aragonite. Most of the aragonite has now been converted into calcite (Halley and Evans, 1983). The Miami Limestone can be classified as oosparitic, or oolitic grainstone, since it is grain supported, and lacks lime mud.
The stops for this field trip ranged from south Miami-Dade county, to the most northerly exposure in central Broward county. Several locations such as Alice Wainwright Park, Coral Way, and numerous outcrops along Bayshore Drive are low-lying bluffs, with Silver Bluff being a wave cut cliff, or bench.
The Miami Limestone is one of three contemporaneous deposits in South Florida; with the Anastasia Formation to the north, and the Key Largo Limestone to the south.
A similar active ooid shoal environment now exists in the Bahamas (Hoffmeister,
Stockman, and Multer, 1967).
