Tamiami Formation

Tamiami Formation
Stratigraphic range: Zanclean-Piacenzian
~4.6–2.7 Ma In the broad sense extends from the Messinian until Gelasian
The Tamiami Formation of Hillsborough County
TypeGeological formation
Unit ofOkeechobee group
Sub-units(See Text)
UnderliesCaloosahatchee Formation, Nashua Formation
OverliesHawthorn Group (see text)
AreaSouth Florida
Thickness8.2–196.9 ft (2.5–60.0 m)
Lithology
PrimaryMarl, Sandstone, Claystone, Limestone
OtherPhosphate, Pyrite, Calcite, rare tektites
Location
RegionSouth Florida
CountryUnited States
Extent~ 17,633.9 miles (28,379.0 km)
Type section
Named forTamiami Trail and Tamiami Canal (US Highway 41)
Named byWendell Clay Mansfield
Year defined1939

Approximate total extent of the Tamiami Formation

The Tamiami Formation (IPA: /ˈt̺ʰæˌmi.ɑːmiː fɔɹˈmeɪʃ(ə)n/) is a Pliocene Konzentrat-Lagerstätte in Southern Florida. The nature of units in the Tamiami Formation is debated, and it has at one point been described by DuBar as a geologic group. As originally defined, the Murdock Station and Bayshore Formations were members of the Tamiami Formation. In the broadest sense (or sensu latissimo, abbreviated here as s.l.) the Tamiami Formation includes the Murdock Station and Bayshore members.

The Tamiami Formation is one of the most biodiverse fossil bearing formations on Earth.

Etymology

The Tamiami Formation derives its name from the southern most stretch of US Highway 41, (the Tamiami Trail) where the formation was first studied in depth. The name of the Tamiami Trail in itself is a portmanteau of the major cities it runs between, Tampa and Miami.

Tampa is named after the Calusa settlement Tanpa, which was actually located around Charlotte Harbor. Miami comes from Mayaimi, the Calusa word for Lake Okeechobee, the last remnant of the Okeechobean Sea preserved within the formation. Mayaimi is further split into Mayai and -mi. Julian Granberry further reconstructs Proto-Tunica forms “*may...” and “*-mi”, with the root meanings glossed as “On the other side” and “Over (there)”

Discovery and history of study

Dredge at work on the construction of the Tamiami Trail
Exposure of the Tamiami Formation in the Tamiami Canal of the Miccosukee Reserved Area.

Prior to the arrival of Europeans, fossils of the Tamiami Formation were exploited by the indigenous people of Florida. Shark teeth from the coast were modified into necklaces and were occasionally fashioned into spears. These teeth are present at known early contact sites. The groups at the time of contact included those of the settlements of Uzita, Mocozo, and Tocobaga; as well as the Calusa, Tequesta and Mayaimi. These teeth were recognized as fossil shark teeth by these indigenous groups. They were preferred for spiritual over utilitarian use. Fossils from the formation may be found as far away as Ohio. Limestones from the Tamiami Formation were used in healing and are found in pre-Columbian burials. Spanish colonists had also noticed the fossil teeth, but mistook them for those of crocodiles.

The construction of the Tamiami Trail began in 1919 where Seminole and Miccosukee people (The descendants of Hitchiti refugees and the previously mentioned indigenous people) guided a trail through the Everglades. Here the inhabitants of the Everglades encountered fossil corals.

Helen Tucker and Druid Wilson published their first description of the Acline Fauna in 1932 in the shell pits of Punta Gorda.

The Tamiami Formation was first formally described along the Tamiami Trail by Wendell Clay Mansfield, in a work that was published posthumously. Mansfield originally called it the “Tamiami Limestone”. The construction of the Tamiami Trail required a canal, which made the study of the formation (with few natural outcrops) more accessible to researchers.

Timothy Abbott Conrad and William Healey Dall were amongst the first researchers to describe taxa from the formation, Mansfield himself being a student of Dall. Both were important pioneer paleomalacologists, and Conrad described local outcrops before Mansfield's formal description.

Julia Anna Gardner, a friend of Mansfield, was amongst the first researchers to describe the paleomalacologic fauna of the Tamiami formation. Today the Paleontological Research Institute in New York houses many of her specimens, although many of her species still remain unassessed.

Axel Olsson first published his description of the Pinecrest Beds in 1964, defining the unit bearing the Acline Fauna.

In the 1980s, various vertebrate sites were found within the Tamiami Formation. The bird layer of the Pinecrest Beds was first discovered at this time, with a death assemblage of cormorants.

The Escalation Hypothesis was developed by the blind Dutch scientist Geerat J. Vermeij's in part due to his observations of gastropod evolution in the Pinecrest Beds.

The Paleomalacologist and Paleoceanographer Edward Petuch is one of the most prolific authors on the Tamiami Formation. Petuch's units of the Pinecrest and Golden Gate members are widely used in publications. Petuch is himself however a controversial figure amongst researchers, criticized as a prolific “splitter”. Nonetheless, as of 2026 many of his species are still upheld as valid.

As of 2026, many aspects of the Tamiami Formation remain understudied. Geological descriptions of the formation are lacking. Micromollusks of the Pinecrest Beds have complicated the already high estimates of biodiversity. Some estimates have additionally placed the Buckingham, Golden Gate, and Ochopee members as having similar rates of endemism to the Acline Fauna of the Pinecrest Beds. Stratigraphic descriptions of many sites (especially outside of Sarasota) are scarce, and many members of the formation are unnamed.

Age

Period: Neogene
Epoch: Latest Miocene to Pliocene
Faunal stage: Blancan

~5.6-2.6 mya, calculates to a period of 3 million years (s.l.)

~4.6-2.6 mya, calculates to a period of 2 million years (s.s.)

Geologic setting

The Tamiami Subsea of Piaceznian Florida

The Tamiami Formation s.l. began deposition within the final years of the Messinian in Murdock Subsea of the Okeechobean Sea. This subsea was dominated by deposition within the Immokalee Delta. Barnacle reefs dominated this area.

The Tamiami (in the strict sense, or sensu stricto, abbreviated here as s.s.) began with deposition in the Pliocene Tamiami Subsea. Florida at this time was split between the Polk Peninsula and the St. Lucie Peninsula. Mammals like camelids, three species of giant ground sloth (including Eremotherium), two armadillos, giant raccoons, walruses, peccaries, seals, giant capybaras, giant gophers, and gompotheres occupied the peninsulas. Birds like gulls, sanderlings, ducks, and flamingoes occupied the coasts. Giant tortoises, softshelled turtles and alligator snapping turtles were also present. Oaks, birches, beeches, maples, pines, sweetgum and holly trees are known from pollen.

Large hurricanes formed with the emergence of the Isthmus of Panama. Quartz sand from the panhandle was carried south, and the Kissimmee River was active in deposition in what was the Kissimmee Embayment. The Everglades region was dominated by the Everglades Pseudoatoll, consisting of various islands and reefs. Whales often traversed the Caloosahatchee and Loxahatchee Straits.

The Buckingham and Ochopee Limestone members were deposited contemporaneously in the Pliocene. Golden Gate Reef Member was deposited in the Middle Pliocene, at a depth of 20-25 meters. The Fruitville Member, (sometimes referred to as the Fruitville Formation) is the uppermost member of the Tamiami Formation.

Mass Extinction Event

The Tamiami Formation's (molluscan) Acline Fauna is more diverse than that of the modern molluscan fauna of the Caribbean. By the time of the overlying Caloosahatchee Formation, large amounts of these species were already extinct. In 1993, Warren Allmon and Gary Rosenburg hypothesized that the Pinecrest Beds displayed high rates of both speciation and extinction throughout its deposition, whilst keeping a small but consistent level of biodiversity. Two years later, Petuch demonstrated a two-stage mass extinction event, the first stage occurring after the Pinecrest Beds, and the second occurring after the Caloosahatchee Formation.

Location

The Tamiami Formation appears in the counties of Charlotte, Lee, Hendry, Hardee, DeSoto, Hillsborough, Pinellas, Collier, Palm Beach, Miami-Dade, Sarasota, Manatee, Okeechobee, and Monroe. It is widespread in Florida and part of the intermediate confining aquifer system. The Tamiami formation overlies the Hawthorn at every locality where the Hawthorn has been penetrated and is overlain unconformably by the Caloosahatchee marl of the Pleistocene in South Florida.

Composition

The Tamiami Formation contains a wide range of mixed carbonate-siliciclastic lithologies and associated faunas. It occurs at or near the land surface in the southern peninsula with numerous named and unnamed members recognized within the Tamiami Formation. Its unevenness indicates that the upper part has been subjected to erosion. Microtektites are known from the Pinecrest Beds.

Lithologies

The Tamiami Formation includes:

Phosphate is present in limited quantities throughout the Tamiami in sand and gravel.

Sub-units

Fossils

Fossil (Cerithium dalli) from the Tamiami Formation

The Tamiami Formation preserves many fossils. These include plants, animals, protists, and haptophytes. and Fossils appear in casts and molds, as well as original material, ichnotaxa, and mineralized forms.

The Tamiami Formation also contains many scientifically and culturally significant fossil taxa. The ancestral species of wolves, dogs, and coyotes, Canis lepophagus, is present in the Pinecrest Beds. The earliest known occurrence of a Cryptochirid, Galacticus duerri was found in the Pinecrest Beds. Ecphora quadricostata, an iconic ecphora snail, is present through the Tamiami Formation.

In culture

The Tamiami Formation has been used for spiritual purposes since humans populated the region. Shark teeth and limestones from the formation were collected for healing purposes and to make ceremonial objects. Fossil shark teeth from the gulf coast are still collected as a hobby and occasionally used for spiritual practice.

The fossil mollusks from the Tamiami Formation are used in road construction and mulches. Fossils from the formation can be found in some asphalt roads and many dirt roads. Concrete in Sarasota and Venice is sometimes decorated with Tamiami formation fossils. Shells of the formation have also been used in the reinterment of Tocobagan People.

References

  1. ↑ Parker, Garald G., 1951, Geologic and hydrologic factors in the perennial yield of the Biscayne aquifer: Jour. Am. Water Works Assoc., v. 43, no. 10, p. 817–834, 7 figs.
  2. ↑ Scott, Thomas M. (2016). "Lithostratigraphy and hydrostratigraphy of Florida". Florida Scientist. 79 (4): 198–207. ISSN 0098-4590. JSTOR 44113185.
  3. ↑ Storozhynska, Nina; Anderson, Brendan; Allmon, Warren D. (2023). "Changes in Drilling and Peeling Predation on Turritellid Gastropods Associated with the Pliocene Western Atlantic Regional Mass Extinction". Geological Society of America Abstracts with Programs. 55 (6) 393122. Bibcode:2023GSAA...5593122S. doi:10.1130/abs/2023AM-393122 – via NSF.
  4. ↑ Gomes, Lucas D.; Petersen, Sierra V.; Portell, Roger W.; Riemersma, Peter E. (2025). "Plio-Pleistocene stratigraphy, paleoenvironments, and sea-level history at Florida Shell Quarry, Charlotte County, Florida, U.S.A." Journal of Sedimentary Research. 95 (2): 367–382. Bibcode:2025JSedR..95..367G. doi:10.2110/jsr.2024.090.
  5. 1 2 3 Mansfield, Wendell C. (1939). "Notes on the upper Tertiary and Pleistocene mollusks of peninsular Florida ( FGS: Bulletin 18 ) | PALMM". palmm.isle.flvc.org. Retrieved 2026-08-24.
  6. ↑ Granberry, Julian (2011-11-30). The Calusa: Linguistic and Cultural Origins and Relationships. University of Alabama Press. ISBN 978-0-8173-1751-5.
  7. 1 2 Maisch IV, Harry M.; Becker, Martin A.; Perez, Victor J.; Shimada, Kenshu (2025). "Sharks and rays (Chondrichthyes: Elasmobranchii) from the Peace River and Tamiami formations (Late Miocene–Early Pliocene) on the submerged continental shelf". Palaeontologia Electronica. doi:10.26879/1529.
  8. ↑ Florida, State Library and Archives of. "Florida Memory • Artifacts from the Hillsborough County archaeology project, Thomas mound site IA". Florida Memory. Retrieved 2026-08-26.
  9. 1 2 Farrell, Aubrey D. (2021). "A Use-Wear and Functional Analysis of Precontact Shark Teeth Assemblages from Florida". repository.lib.fsu.edu. Retrieved 2026-08-26.
  10. ↑ Cordell, Ann S.; Mitchem, Jeffrey M. (2021-09-27). Methods, Mounds, and Missions: New Contributions to Florida Archaeology. University Press of Florida. ISBN 978-1-68340-338-8.
  11. ↑ "Tales of the Tamiami Trail". Seminole Tribal Historic Preservation Office. Retrieved 2026-08-27.
  12. ↑ Missimer, Thomas M.; Tobias, Amy E. (2004). "Geology and Paleontology of a Caloosahatchee Formation Deposit Near Lehigh, Florida". Florida Scientist. 67 (1): 48–62. ISSN 0098-4590. JSTOR 24321198.
  13. 1 2 3 4 5 6 7 8 9 Petuch, Edward J. (2021). Ancient Seas of Southern Florida (2nd ed.). CRC Press.
  14. 1 2 Gardner, J A (1939). "Wendell Clay Mansfield". The Nautilus. 53. American Malacologists, inc., etc: 64–65.
  15. ↑ Archives, Smithsonian Institution (2022). "Accession 08-141 Julia Anna Gardner Papers, 1894-1961". Smithsonian Institution Archives. Smithsonian Institution. Retrieved 2026-08-27.
  16. 1 2 3 4 Emslie, Steven D.; Morgan, Gary S. (1994-04-29). "A Catastrophic Death Assemblage and Paleoclimatic Implications of Pliocene Seabirds of Florida". Science. 264 (5159). American Association for the Advancement of Science: 684–685. Bibcode:1994Sci...264..684E. doi:10.1126/science.264.5159.684. PMID 17737952.
  17. ↑ Vermeij, Geerat J. (2021-02-09). Evolution and Escalation: An Ecological History of Life. Princeton University Press. doi:10.2307/j.ctv18zhf8b. ISBN 978-0-691-22424-4. JSTOR j.ctv18zhf8b.
  18. 1 2 3 Willard, Debra A. (1993). "Pliocene palynomorph census data from the Pinecrest Beds (Tamiami Formation) in Quality Aggregates Phase 6 Pit, southwestern Florida". Open-File Report (Report). U.S. Geological Survey. doi:10.3133/ofr93563.
  19. 1 2 3 4 5 Meeder, J. F.; Klaus, J. S.; Grasmueck, M. (2019-09-20). "Ramp reef depositional facies model for the Mid-Pliocene Golden Gates Reef Member of the Tamiami Formation, South Florida". Facies. 65 (4): 40. Bibcode:2019Faci...65...40M. doi:10.1007/s10347-019-0582-3. ISSN 1612-4820.
  20. ↑ Whicher, John (2008). "The Fort Drum Crystal Mine, Florida, USA". Geology Today. 24 (2): 59–61. Bibcode:2008GeolT..24...59W. doi:10.1111/j.1365-2451.2008.00658.x. ISSN 1365-2451.
  21. ↑ "WoRMS - World Register of Marine Species". www.marinespecies.org. Retrieved 2026-08-27.
  22. ↑ Allmon, Warren D.; Rosenberg, Gary (1993-06-11). "Diversity of Atlantic coastal plain mollusks since the Pliocene". Science. 260 (5114): 1626–1629. Bibcode:1993Sci...260.1626A. doi:10.1126/science.260.5114.1626. PMID 17810204.
  23. ↑ Petuch, Edward J. (1995-10-13). "Molluscan diversity in the late Neogene of Florida: Evidence for a two-staged mass extinction". Science. 270 (5234): 275–277. Bibcode:1995Sci...270..275P. doi:10.1126/science.270.5234.275.
  24. ↑ Mansfield, W. C., 1939, Notes on the upper Tertiary and Pleistocene mollusks of peninsular Florida: Florida Geological Survey Bulletin 18, 75 p.
  25. ↑ Missimer, T.M., 1992, Stratigraphic relationships of sediment facies within the Tamiami Formation of southwestern Florida: Proposed intraformational correlations; in Scott, T.M., and Allmon, W.D., (eds.), The Plio-Pleistocene stratigraphy and paleontology of southern Florida; Florida Geological Survey Special Publication 36, p. 63–92.

Further reading