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 exp ...

s of Late Oligocene to

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 primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. 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 pentoxi ...

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, ...

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, 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 by ...

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:

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 Before Present, BP, a period of .

~28.4 to ~2.588

mya Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese ...

, 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 201 ...

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 incl ...

. 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 cover ...

Citrus ''Citrus'' is a genus of flowering plant, flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as Orange (fruit), oranges, Lemon, lemons, grapefruits, pomelos, and lim ...

, 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 ...

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, Indian ...

at depths ranging from

mean sea level There are several kinds of mean in mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. ...

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 mya, ...

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 The Arcadia Formation and its sub-unit, the Tampa Member, are Late Oligocene geologic formations in North Florida, United States. It is part of the Hawthorn Group. Age Period: Paleogene to Neogene Epoch: Early Late Oligocene through Pliocene F ...

Coosawhatchie Formation The Coosawhatchie Formation is a Miocene geologic formation with an outcrop in North Florida. It is within the Hawthorn Group. Age Period: Neogene Epoch: Miocene ~23.03 to 5.33 mya, calculates to a period of {{Mya, 23.03-5.33, million years Fa ...

(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 conflue ...

(Miocene-Pliocene) *

Statenville Formation The Statenville Formation is a geological formation of northern Florida, USA. Age Period: Neogene Epoch: Miocene Faunal stage: Chattian through early Blancan ~28.4 to ~2.588 mya, calculates to a period of Location The Statenville Formation is ...

(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, calculates to a ...

(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 type ...

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

'' (Mud Snake) *''

Heterodon ''Heterodon'' is a genus of harmless colubrid snakes endemic to North America.Platt, Dwight R. 1983. Heterodon'. Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, 351: 1-2. They are stout with up ...

'' (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. Althoug ...

'' (Rat Snake) *''

Lampropeltis getulus ''Lampropeltis getula'', commonly known as the eastern kingsnake, Conant R (1975). ''A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition''. (First published in 1958). Boston: Houghton Mifflin Company. 42 ...

'' (Kingsnake) *'' Nerodia'' (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'' (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 and ...

'' (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 ''Egretta'' is a genus of medium-sized herons, mostly breeding in warmer climates. Representatives of this genus are found in most of the world, and the little egret, as well as being widespread throughout much of the Old World, has now started ...

'' (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 Aramidae is a bird family in the order Gruiformes. The limpkin The limpkin (''Aramus guarauna''), also called carrao, courlan, and crying bird, is a large wading bird related to rails and cranes, and the only extant species in the family Ara ...

'' (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, althoug ...

'' (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 widespread ...

'' (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'' (Eagle) *'' Passeriformes'' (Songbird) Mammals *†'' Metaxytherium floridanum'' (Sea Cow) *†''

Gomphotherium ''Gomphotherium'' (; "welded beast") is an extinct genus of proboscids from the Neogene and early Pleistocene of Eurasia, Africa, North America and Asia. As of 2021, two species, ''G. annectens'' and possibly ''G. subtapiroideum'', are also kno ...

'' (Elephant) *†'' Tapirus simpsoni'' (Tapir) *†'' Teleoceras proterum'' (Rhinoceros) *†''

Aphelops ''Aphelops'' (Greek: "smooth" (apheles), "face" (ops), in a reference of lacking a horn) is an extinct genus of hornless rhinoceros endemic to North America. It lived from the Middle Miocene to the early Pliocene, during which it was a common com ...

malacorhinus'' (Rhinoceros) *†''

Pseudhipparion ''Pseudhipparion'' is an extinct genus of three-toed horse endemic to North America during the Miocene. They were herding animals whose diet consisted of C3 plants. Fossils found in Georgia and Florida Florida is a state located in the ...

skinneri'' (Horse) *†''

Hipparion ''Hipparion'' (Greek, "pony") is an extinct genus of horse that lived in North America, Asia, Europe, and Africa during the Miocene through Pleistocene ~23 Mya—781,000 years ago. It lived in non-forested, grassy plains, shortgrass prairie or st ...

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), from about 13.6 Ma to 5.3 Ma. Analysis of ''Proto ...

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

Sthenictis ''Sthenictis'' is an extinct genus in the weasel family (mustelids) endemic to North America and Asia during the Miocene epoch living from ~15.97—5.33 Ma ( AEO) existing for approximately . Fossil distribution The oldest specimen was uncovere ...

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. They were small and weighed around . They first appeared in North America around 34 million years ago in the Oligocene at the same ...

'' *†''

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 Hemphillian of ...

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 t ...

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

Yumaceras ''Yumaceras'' is an extinct genus of antelope-like palaeomerycid artiodactyl endemic to North America from the Miocene epoch, 13.6—5.33 Ma, existing for approximately . Taxonomy ''Yumaceras'' was named by Frick (1937). It was synonymized sub ...

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 them ...

'' (Whale) *†'' Aepycamelus major'' (Camel) *†'' Procamelus grandis'' (Camel) *†'' Hemiauchenia minima'' (Camel) *'' Talpidae'' (Mole) *'' Soricidae'' (Shrew) *†'' Archaeolaginae (Rabbit) *'' Sciuridae'' (Squirrel) *†''

Eucastor ''Eucastor'' is an extinct genus (biology), genus of beaver-grouped rodents. Based on the available evidence of the Foramen, foramina, ''Eucastor'' most likely is closely related to Beaver, ''Castor'', but not in its direct lineage. References ...

planus'' (Beaver) *'' Abelmoschomys simpsoni'' (Vole) *†''

Mylagaulus ''Mylagaulus'' is an extinct genus of rodents in the family Mylagaulidae. ''Mylagaulus'' lived in the Americas during the middle to late Miocene. The genus contains the following species: *''M. cambridgensis'' *''M. cornusaulax'' Czaplewski, 20 ...

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