The Hawthorn Group is a stratigraphic unit that includes several

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

s of

Late Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/ Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58North Florida,

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

. It is known for its

phosphate rock Phosphorite, phosphate rock or rock phosphate is a non-detrital sedimentary rock that contains high amounts of phosphate minerals. The phosphate content of phosphorite (or grade of phosphate rock) varies greatly, from 4% to 20% phosphorus pento ...

resources, and for its rich assemblages of

Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s. It was originally called the Waldo Formation by L.C. Johnson of the

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

in 1887, and later became the Hawthorne Group named for

Hawthorne, Florida Hawthorne () is a city in Alachua County, Florida, United States, incorporated in 1881. Indigenous peoples of the Americas had been living in the area since around 100 CE; Hawthorne grew around their trading trails. Throughout its history, Hawth ...

, where its phosphate-rich rock was quarried and processed for use as fertilizer.

Age

Period:

Epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided ...

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Faunal stage In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convent ...

Chattian The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

through early

Blancan The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 4,750,000 to 1,806,000 years BP, a period of .mya, a period of

Location

The Hawthorn Group extends from

Suwannee County Suwannee County is a county located in the north central portion of the state of Florida. As of the 2020 census, the population was 43,474, up from 41,551 in 2010. Its county seat is Live Oak. Suwannee County was a dry county until August 20 ...

in the north and southward to

Hernando County Hernando County is a county located on the west central coast of the U.S. state of Florida. As of the 2020 census, the population was 194,515. Its county seat is Brooksville, and its largest community is Spring Hill. Hernando County is i ...

. It encompasses in part the counties of Gilchrist, Levy,

Dixie Dixie, also known as Dixieland or Dixie's Land, is a nickname for all or part of the Southern United States. While there is no official definition of this region (and the included areas shift over the years), or the extent of the area it cove ...

Citrus ''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, lemons, grapefruits, pomelos, and limes. The genus ''Citrus'' is native to ...

, Sumter, Alachua and Marion County. The Hawthorn is also present below undifferentiated sediments (TQu) as well as the

Tamiami Formation The Tamiami Formation is a Late Miocene to Pliocene geologic formation in the southwest Florida peninsula. Age Period: Neogene Epoch: Late Miocene to Pliocene Faunal stage: Clarendonian through Blancan ~13.06–2.588 mya, calculates to a pe ...

from Polk County south through Highlands, Glades, Hendry, Dade, Collier, and

Monroe County Monroe County may refer to seventeen counties in the United States, all named for James Monroe: *Monroe County, Alabama * Monroe County, Arkansas * Monroe County, Florida *Monroe County, Georgia * Monroe County, Illinois * Monroe County, Indi ...

at depths ranging from

mean sea level There are several kinds of mean in mathematics, especially in statistics. Each mean serves to summarize a given group of data, often to better understand the overall value ( magnitude and sign) of a given data set. For a data set, the '' ...

near Polk to below 600 meters in Monroe Co. The Hawthorn overlies

Ocala Limestone The Ocala Limestone is a late Eocene geologic formation of exposed limestones near Ocala, Marion County, Florida. Age Period: Paleogene Epoch: Late Eocene Faunal stage: Late Clarkforkian through early Orellan Absolute Age: ~55.8 to ~33.9 ...

Glen L. Faulkner, Geological Survey (U.S.), United States. Army. Corps of Engineers, Geohydrology of the Cross-Florida Barge Canal area, Tallahassee, 1973.

Sub-units

* Arcadia Formation *

Coosawhatchie Formation The Coosawhatchie Formation is a Miocene geologic formation with an outcrop in North Florida. It is within the Hawthorn Group. Age Period (geology), Period: Neogene Epoch (geology), Epoch: Miocene ~23.03 to 5.33 Mya (unit), mya, calculates to a ...

(Miocene-Pliocene) *

Peace River Formation The Peace River Formation is a stratigraphical unit of middle Albian age in the Western Canadian Sedimentary Basin. It takes the name from the Peace River, and was first described on the banks of the river, downstream from the Smoky River conflu ...

(Miocene-Pliocene) * Statenville Formation (Miocene) *

Torreya Formation The Torreya Formation is a Miocene geologic formation with an outcrop in North Florida. It is within the Hawthorn Group. Age Period: Neogene Epoch: Early Miocene Faunal stage: Aquitanian through early Messinian ~19–15.3 mya, calculat ...

(Miocene)

Paleofauna

Reptiles *''

Apalone ferox The Florida softshell turtle (''Apalone ferox'') is a species of softshell turtle native to the Southeastern United States.Rafinesque, Constantine S. "12. Description of two new genera of Soft Shell Turtles of North America." Atlantic Journal, a ...

'' (Florida Softshell Turtle) *'' Pseudemys caelata'' (Pond Turtle) *'' Terrapene'' (Box Turtle) *'' Deirochelys'' (Chicken Turtle) *''

Geochelone ''Geochelone'' is a genus of tortoises. ''Geochelone'' tortoises, which are also known as typical tortoises or terrestrial turtles, can be found in southern Asia. They primarily eat plants. Species The genus consists of two extant species: A n ...

'' (Tortoise) *'' Alligator mississippiensis'' (American Alligator) *†''

Gavialosuchus ''Gavialosuchus'' is an extinct genus of gavialid crocodylian from the early Miocene of Europe. Currently only one species is recognized, as a few other species of ''Gavialosuchus'' have since been reclassified to other genera. Taxonomy The typ ...

americanus'' or '' Thecachampsa antiqua'' (American Crocodile) *''

Typhlops ''Typhlops'' is a genus of blind snakes in the family Typhlopidae. The genus is endemic to the West Indies. Some species which were formerly placed in the genus ''Typhlops'' have been moved to the genera ''Afrotyphlops, Amerotyphlops, Anilios, ...

'' (Blind snake) *''

Xenodontinae Xenodontinae is a subfamily of snakes in the family Colubridae. The subfamily Xenodontinae encompasses a number of rear-fanged (opisthoglyphous), mildly venomous snake genera found in South America and the Caribbean. Members of the subfamily Xen ...

'' (Mud Snake) *'' Heterodon'' (Hognose Snake) *''

Elaphe ''Elaphe'' is a genus of snakes in the family Colubridae. ''Elaphe'' is one of the main genera of the rat snakes, which are found in many regions of the northern hemisphere. ''Elaphe'' species are medium to large constrictors by nature. Alth ...

'' (Rat Snake) *''

Lampropeltis getulus ''Lampropeltis getula'', commonly known as the eastern kingsnake,Roger Conant (herpetologist), Conant R (1975). ''A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition''. (First published in 1958). Boston: ...

'' (Kingsnake) *''

Nerodia ''Nerodia'' is a genus of nonvenomous colubrid snakes commonly referred to as water snakes due to their aquatic behavior. The genus includes nine species, all native to North America. Description ''Nerodia'' species vary greatly, but all are ...

'' (Water snake) *'' Thamnophis'' (Garter Snake) *''

Crotalinae The Crotalinae, commonly known as pit vipers,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . crotaline snakes (from grc, κρόταλον ''krotalon'' castanet), or pit adders, are a subfa ...

'' (Lancehead, Rattlesnake) *''

Sistrurus :''Common names: ground rattlesnakes, pygmy rattlesnakes, massasaugas'' Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates, a Division of Cornell University Press ...

'' (Rattlesnake) Birds *''

Anserinae The Anserinae are a subfamily in the waterfowl family Anatidae. It includes the swans and true geese. Under alternative systematical concepts (see e.g., Terres & NAS, 1991), it is split into two subfamilies, the Anserinae contain the geese ...

'' (Swan) *'' Podicipedidae'' (Grebe) *'' Phalacrocoracidae'' (Cormorant) *''

Anhinga The anhinga (; ''Anhinga anhinga''), sometimes called snakebird, darter, American darter, or water turkey, is a water bird of the warmer parts of the Americas. The word ''anhinga'' comes from ''a'ñinga'' in the Brazilian Tupi language and means ...

grandis'' (Snakebird) *'' Ciconiidae'' (Stork) *'' Phoenicopteridae'' (Flamingo) *'' Ardea'' (Heron) *'' Egretta'' (Egret) *''

Ardeola Pond herons (''Ardeola'') are herons, typically long with an wingspan. Most breed in the tropical Old World, but the migratory squacco heron occurs in southern Europe and the Middle East and winters in Africa. The scientific name comes from L ...

'' (Heron) *'' Aramidae'' (Limpkin) *'' Gruidae'' (Crane-like) *''

Rallidae The rails, or Rallidae, are a large cosmopolitan family of small- to medium-sized, ground-living birds. The family exhibits considerable diversity and includes the crakes, coots, and gallinules. Many species are associated with wetlands, alth ...

'' (Crakes & Coots) *''

Cathartidae The New World vulture or condor family, Cathartidae, contains seven extant species in five genera. It includes five extant vultures and two extant condors found in warm and temperate areas of the Americas. The "New World" vultures were widespr ...

'' (New World Vulture) *''

Pandionidae ''Pandion'' is a genus of birds of prey, known as ospreys, the only genus of family Pandionidae. Most taxonomic treatments have regarded this genus as describing a single extant species, separated to subspecies or races, while some treatments rec ...

'' (Osprey) *''

Accipitridae The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-s ...

'' (Eagle) *''

Passeriformes A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...

'' (Songbird) Mammals *†'' Metaxytherium floridanum'' (Sea Cow) *†'' Gomphotherium'' (Elephant) *†''

Tapirus ''Tapirus'' is a genus of tapir which contains the three living American tapir species. The Malayan tapir is usually included in ''Tapirus'' as well, although some authorities have moved it into its own genus, '' Acrocodia''. Extant species Th ...

simpsoni'' (Tapir) *†'' Teleoceras proterum'' (Rhinoceros) *†'' Aphelops malacorhinus'' (Rhinoceros) *†'' Pseudhipparion skinneri'' (Horse) *†'' Hipparion tehonense'' (Horse) *†'' Neohipparion trampasense'' (Horse) *†'' Nannippus westoni'' (Horse) *†''

Hippotherium ''Hippotherium'' is an extinct genus of horse that lived in during the Miocene through Pliocene ~13.65—3.3 Mya, existing for . Species The type species, ''H. primigenius'', is known from Miocene deposits in Europe and the Middle East ...

ingenuum'' and ''H. plicatile'' (Horse) *†'' Calippus cerasinus'' and ''C. elachistus'' (Horse) *†''

Protohippus ''Protohippus'' is an extinct three-toed genus of horse. It was roughly the size of a modern donkey. Fossil evidence suggests that it lived during the Late Miocene (Clarendonian to Hemphillian The Hemphillian North American Stage on the geolog ...

gidleyi'' (Horse) *'' Microchiroptera'' (Microbat) *†'' Leptarctus'' (Mustelidae) *†'' Hoplictis'' (Mustelidae) *†'' Plionictis'' (Mustelidae) *†'' Sthenictis lacota'' (Mustelidae) *†''

Arctonasua ''Arctonasua'' is an extinct genus of raccoon-like procyonid of the Miocene, endemic to North America. It lived from ~16.0—4.9 Mya, existing for approximately . Species * ''A. eurybates'' Baskin, 1982 - Sioux County, Nebraska, estimated age ...

floridana'' (Raccoon) *†'' Paranasua biradica'' *†''

Leptocyon The genus ''Leptocyon'' (Greek: ''leptos'' slender + ''cyon'' dog) includes 11 species and was the first canine Canine may refer to: Zoology and anatomy * a dog-like Canid animal in the subfamily Caninae ** ''Canis'', a genus including dogs, w ...

'' *†''

Epicyon ''Epicyon'' ("more than a dog") is a large, extinct, canid genus of the subfamily Borophaginae ("bone-crushing dogs"), native to North America. ''Epicyon'' existed for about from the Hemingfordian age of the Early Miocene, to the Hemphillia ...

haydeni'' and ''E. saevus'' (Proto-dog) *†'' Nimravides galiani'' (False Saber-tooth cat) *†''

Barbourofelis ''Barbourofelis'' is an extinct genus of large, predatory, feliform carnivoran mammals of the family Barbourofelidae (false saber-tooth cats). The genus was endemic to North America and Eurasia during the Miocene until its extinction during ...

loveorum'' (False Saber-tooth cat) *†'' Antilocaprinae'' (Antilope) *†'' Pseudoceras'' (Early horse-type ungulate) *†'' Yumaceras hamiltoni'' (Camel-like) *†''

Cetacea Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel th ...

'' (Whale) *†'' Aepycamelus major'' (Camel) *†'' Procamelus grandis'' (Camel) *†''

Hemiauchenia ''Hemiauchenia'' is a genus of laminoid camelids that evolved in North America in the Miocene period about 10 million years ago. This genus diversified and moved to South America in the Early Pleistocene, as part of the Great American Biotic I ...

minima'' (Camel) *'' Talpidae'' (Mole) *'' Soricidae'' (Shrew) *†'' Archaeolaginae (Rabbit) *''

Sciuridae Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squ ...

'' (Squirrel) *†''

Eucastor ''Eucastor'' is an extinct genus of beaver-grouped rodents. Based on the available evidence of the foramina In anatomy and osteology, a foramen (;Abelmoschomys simpsoni'' (Vole) *†''

Mylagaulus ''Mylagaulus'' is an extinct genus of rodents in the family Mylagaulidae. ''Mylagaulus'' lived in the Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South A ...

elassos'' (Horned gopher)

References

{{reflist *USGS: Florida Geology
/small> *Paleobiology database: Love Bone Bed Collection
/small> Geologic groups of Florida Neogene Florida Paleogene Florida Oligocene Series of North America Miocene Series of North America Paleontology in Florida Miocene United States