The Suwannee Limestone is an Early Oligocene geologic formation of exposed fossiliferous limestones in North Florida, United States.
Description Suwannee Limestone is found in the peninsula carbonate outcroppings on the northwestern, northeastern and southwestern flanks of the Ocala Platform. However, Suwannee Limestone is not present on an area known as Orange Island on the eastern side of the Ocala Platform due to erosion, nondeposition or both.Bryan, J.R., 1991, Stratigraphic and paleontologic studies of Paleocene and Oligocene carbonate facies of the eastern Gulf Coastal Plain: unpublished Ph.D. dissertation, University of Tennessee, Knoxville, TN, 324 p. This limestone is present in southeastern Leon, Jefferson, Madison, Taylor, Lafayette counties as well as Hamilton along the upper Suwannee River basin, and southward into Suwannee County, Florida.
Early Oligocene Suwannee Limestone was recognized in the northwestern peninsula by P. F. Huddleston in 1993 as a triple subdivision of Suwannee Limestone, Ellaville Limestone, and Suwannacoochee Dolostone.Huddleston, P.F., A revision of the lithostratigraphic units of the Coastal Plain of Georgia - The Oligocene: Georgia Geological Survey Bulletin 105, 152 p. The Suwannacoochee Dolostone was later officially renamed as the Suwannacoochee Dolomite.Stamm, N., 2018, Geologic Unit: Suwannacoochee. National Geologic Map Database Geolex — Unit Summary, U.S. Department of the Interior, U.S. Geological Survey, Reston Virginia.
Sedimentology Suwannee Limestone consists of a white to cream, poorly to well hardened, fossil rich, vuggy to moldic grainstone and packstone. The dolomitized parts of the Suwannee Limestone are gray, tan, light brown to moderate brown, moderately to well indurated (hard), finely to coarsely crystalline, dolomite with limited occurrences of fossil-bearing beds. Limestone in silicate form is common in Suwannee Limestone.Cooke, C. W., and Mansfield, W. C., 1936, Suwanne Limestone of Florida (abstract): Geological Society of America Proceedings, 1935, p. 71–72.USGS: Geology of Florida
Stratigraphy The Suwannee Limestone overlies the Ocala Limestone and forms part of the intermediate confining unit/aquifer system. (USGS)
Paleobiota The Suwannee Limestone preserves numerous calcifying marine invertebrates, including foraminifers, echinoids, bryozoans and mollusks. Shark teeth belonging to Ginglymostoma and Carcharhinus are known from the Brooksville 2 site, which likely originate from the limestone formation rather than the fissure-fill fauna from the same locality.
Fissure-fill fauna Not long after the formation of the Suwannee Limestone, falling sea levels during the latter part of the Oligocene led to its exposure on land. Terrestrial vertebrates that inhabited this newly-exposed karstic landscape at the time sometimes became trapped within sinkholes that opened in the limestone, which filled up with sand and clay as fissure-fill deposits, fossilizing their remains. These deposits date to the latest Oligocene (late Chattian or Arikareean stage), and preserve numerous animals whose remains are otherwise rare in the region due to a lack of terrestrial deposits. Two major localities that preserve such fossils are Brooksville 2 in Hernando County and SB-lA/Live Oak in Suwanee County.
The following fauna is known:
Amphibia
Anura GenusSpeciesLocalityMaterialNotesImagesEleutherodactylusE. sp.Brooksville 2, Live Oak174 fossilsAn eleutherodactylid frog. The dominant frog taxon at the Brooksville site.Hylidae indet.A tree frog of uncertain affinities.Ranidae indet.A true frog of uncertain affinities.RhinophryneR. sp.Brooksville 2A rhinophrynid frog, related to the modern Mexican burrowing toad.Scaphiopodidae indet.A spadefoot toad of uncertain affinities.
Caudata GenusSpeciesLocalityMaterialNotesImagesNotophthalmusN. sp.Brooksville 2A newt.Sirenidae indet.Brooksville 2A sirenid.
Mammalia
Metatheria GenusSpeciesLocalityMaterialNotesImagesHerpetotherium H. sp.Brooksville 2, Live OakA herpetotheriid.
Eulipotyphla GenusSpeciesLocalityMaterialNotesImagesCentetodon C. magnusBrooksville 2A geolabidid.ParvericiusP. montanusBrooksville 2An erinaceid related to modern hedgehogs.
Perissodactyla GenusSpeciesLocalityMaterialNotesImagesMiohippusM. sp.Brooksville 2A three-toed horse.
Artiodactyla GenusSpeciesLocalityMaterialNotesImagesNanotragulusN. loomisiBrooksville 2A hypertragulid.NothokemasN. waldropiBrooksville 2, Live OakA camelid.Phenacocoelinae indet.An merycoidodontid of uncertain affinities.
Carnivora GenusSpeciesLocalityMaterialNotesImagesAcheronictisA. webbiBrooksville 2A mustelid.ArikarictisA. chapiniBrooksville 2, Live OakA mustelid.DaphoenodonD. sp.Live OakAn amphicyonid.EnhydrocyonE. cf. pahinsintewakpaBrooksville 2A hesperocyonine canid.MammacyonM. sp.Live OakAn amphicyonid.?Leptocyon?L. sp.Live OakA canine.MegalictisM. sp.Live OakAn oligobunine mustelid.OsbornodonO. wangiBrooksville 2A hesperocyonine canid.PalaeogaleP. minutaBrooksville 2, Live OakA palaeogalid.PhlaocyonP. tayloriBrooksville 2, Live OakA borophagine canid.
Chiroptera GenusSpeciesLocalityMaterialNotesImagesEmballonuridae indet.Brooksville 2A sac-winged bat of uncertain affinities.Mormoopidae indet.Brooksville 2A ghost-faced bat of uncertain affinities.Phyllostomidae indet.Brooksville 2A leaf-nosed bat of uncertain affinities.KoopmanycterisK. palaeomormoopsBrooksville 2A ghost-faced bat.Vespertilionidae indet.Brooksville 2A vesper bat of uncertain affinities.
Lagomorpha GenusSpeciesLocalityMaterialNotesImagesMegalagusM. abaconisBrooksville 2A leporid related to modern hares and rabbits.
Rodentia GenusSpeciesLocalityMaterialNotesImagesAgnotocastorA. sp.Brooksville 2A castorid related to modern beavers.Entoptychinae indet.Brooksville 2, Live OakAn entoptychid geomyoid of uncertain affinities.Eomyidae indet.Brooksville 2An eomyid of uncertain affinities.Florentiamyidae indet.Brooksville 2A florentiamyid of uncertain affinities.Heliscomyidae indet.Brooksville 2A heliscomyid of uncertain affinities.ProheteromysP. sp.Brooksville 2, Live OakSciuridae indet.Brooksville 2A squirrel of uncertain affinities.
Aves GenusSpeciesLocalityMaterialNotesImagesGalliformes indet.Brooksville 2A landfowl of uncertain affinities.
Reptilia
Crocodylia GenusSpeciesLocalityMaterialNotesImagesAlligatorA. sp.Brooksville 2A small-sized alligator.
Testudines GenusSpeciesLocalityMaterialNotesImagesTestudinidae indet.Brooksville 2A small-sized tortoise of uncertain affinities.XenochelysX. floridensisBrooksville 2A kinosternoid turtle.
Squamata GenusSpeciesLocalityMaterialNotesImagesAnolisA. "informal morphotype A"Brooksville 2An anole, two morphotypes known.cf. A. "informal morphotype B"CalamagrasC. sp.Brooksville 2A boid.Eublepharidae indet.Brooksville 2An eyelid gecko of uncertain affinities.GeringophisG. sp.Brooksville 2A boid.Helodermatidae indet.Brooksville 2A beaded lizard of uncertain affinities.Iguanidae indet.Brooksville 2An iguanid of uncertain affinities.OgmophisO. sp.Brooksville 2A boid.Rhineuridae indet.Brooksville 2A rhineurid amphisbaenian, related to the modern Florida worm lizard.Scincidae indet.Brooksville 2A skink of uncertain affinities.Scolecophidia indet.Brooksville 2A blindsnake of uncertain affinities.
References