| Hawthorn Group | |
|---|---|
| Stratigraphic range: Miocene | |
| Type | Group |
| Sub-units | (See text) |
| Overlies | Ocala Limestone |
| Thickness | > 330 feet |
| Location | |
| Region | Southeastern United States |
| Country | 
United States |
| Type section | |
| Named for | Hawthorne, Florida |
| Named by | L.C. Johnson, 1887 |
The Hawthorn Group (previously called Hawthorn Formation) is a stratigraphic unit of Miocene age in South Carolina, Georgia, and Florida, in the United States. It is known for its phosphate rock resources, and for its rich assemblages of Neogene vertebrate fossils.
The Waldo Formation was described by L.C. Johnson of the United States Geological Survey in 1887. It was later included in the Hawthorne Beds, named for Hawthorne, Florida, where its phosphate-rich rock was quarried and processed for use as fertilizer. The Hawthrone Beds were later renamed the Hawthorne Formation. (The "e" was eventually dropped from "Hawthorn".) Late in the 20th century the Hawthorn Formation was redesignated as the Hawthorn Group consisting of several formations. [1]
The Hawthorn Group is the widest spread stratigraphic unit of Miocene age in the southeastern United States, making up almost the entire thickness of Miocene strata over the area in which it occurs. The Hawthorn group has complex bedding, primarily consisting of clay, silt and sand. Stratigraphy varies, but the group usually consist of three main zones, a lower calcareous zone, a middle clastic zone, and an upper mixed zone of clastic and carbonate rocks. Phosphate deposits are found throughout the Hawthorn group, but particularly in the lower zone, where beds of dolomite and dolomitic limestone are found. Hawthorn Group deposits are mined for phosphate in central Florida. [2]
Age
Period:
Neogene
Epoch:
Miocene
Faunal stage:
Chattian through early
Blancan ~28.4 to ~2.588
mya, a period of
25.512 million years
Location
The Hawthorn Group includes several geologic formations found in southeastern South Carolina, the coastal plain of Georgia, and much of the Florida Peninsula.The Hawthorn Group extends from southeastern South Carolina through the coastal plain of Georgia and the Florida Peninsula to south Florida. The top member of the Hawthorn Group in southeastern South Carolina and northeastern Georgia is the Coosawhatchie Clay, of middle ( Serravallian) Miocene age. [3]
In Florida, the Hawthorn Group encompasses in part the counties of Gilchrist, Levy, Dixie, Citrus, Sumter, Alachua and Marion County. The Hawthorn is also present below undifferentiated sediments (TQu) as well as the Tamiami Formation from Polk County south through Highlands, Glades, Hendry, Dade, Collier, and Monroe County at depths ranging from mean sea level near Polk to below 600 meters in Monroe Co. [4] The Hawthorn overlies Ocala Limestone [5]
Sub-units
- Arcadia Formation
- Coosawhatchie Formation (Miocene-Pliocene)
- Peace River Formation (Miocene-Pliocene)
- Statenville Formation (Miocene)
- Torreya Formation (Miocene)
Paleofauna
Reptiles
- Apalone ferox (Florida Softshell Turtle)
- Pseudemys caelata (Pond Turtle)
- Terrapene (Box Turtle)
- Deirochelys (Chicken Turtle)
- Geochelone (Tortoise)
- Alligator mississippiensis (American Alligator)
- † Gavialosuchus americanus or Thecachampsa antiqua (American Crocodile)
- Typhlops (Blind snake)
- Xenodontinae (Mud Snake)
- Heterodon (Hognose Snake)
- Elaphe (Rat Snake)
- Lampropeltis getulus (Kingsnake)
- Nerodia (Water snake)
- Thamnophis (Garter Snake)
- Crotalinae (Lancehead, Rattlesnake)
- Sistrurus (Rattlesnake)
Birds
- Anserinae (Swan)
- Podicipedidae (Grebe)
- Phalacrocoracidae (Cormorant)
- Anhinga grandis (Snakebird)
- Ciconiidae (Stork)
- Phoenicopteridae (Flamingo)
- Ardea (Heron)
- Egretta (Egret)
- Ardeola (Heron)
- Aramidae (Limpkin)
- Gruidae (Crane-like)
- Rallidae (Crakes & Coots)
- Cathartidae (New World Vulture)
- Pandionidae (Osprey)
- Accipitridae (Eagle)
- Passeriformes (Songbird)
Mammals
- † Metaxytherium floridanum (Sea Cow)
- † Gomphotherium (Elephant)
- † Tapirus simpsoni (Tapir)
- † Teleoceras proterum (Rhinoceros)
- † Aphelops malacorhinus (Rhinoceros)
- † Pseudhipparion skinneri (Horse)
- † Hipparion tehonense (Horse)
- † Neohipparion trampasense (Horse)
- † Nannippus westoni (Horse)
- † Hippotherium ingenuum and H. plicatile (Horse)
- † Calippus cerasinus and C. elachistus (Horse)
- † Protohippus gidleyi (Horse)
- Microchiroptera (Microbat)
- † Leptarctus (Mustelidae)
- † Hoplictis (Mustelidae)
- † Plionictis (Mustelidae)
- † Sthenictis lacota (Mustelidae)
- † Arctonasua floridana (Raccoon)
- † Paranasua biradica
- † Leptocyon
- † Epicyon haydeni and E. saevus (Proto-dog)
- † Nimravides galiani (False Saber-tooth cat)
- † Barbourofelis loveorum (False Saber-tooth cat)
- † Antilocaprinae (Antilope)
- † Pseudoceras (Early horse-type ungulate)
- † Yumaceras hamiltoni (Camel-like)
- † Cetacea (Whale)
- † Aepycamelus major (Camel)
- † Procamelus grandis (Camel)
- † Hemiauchenia minima (Camel)
- Talpidae (Mole)
- Soricidae (Shrew)
- † Archaeolaginae (Rabbit)
- Sciuridae (Squirrel)
- † Eucastor planus (Beaver)
- Abelmoschomys simpsoni (Vole)
- † Mylagaulus elassos (Horned gopher)
See also
References
- ^ "Geology of Florida Miocene to Holocene Chapter 5". University of Florida Geology Department. Archived from the original on March 16, 2012. Retrieved March 22, 2024.
- ^ Miller, James A. (1986). Hydrogeologic Framework of the Florida Aquifer System in Florida and in Parts of Georgia, Alabama, and South Carolina (U.S. Geographical Survey Professional Paper 1403-B) (PDF) (Report). Washington, D.C.: U.S. Geological Survey. p. B37.
- ^ Abbott, William H.; Andrews, George W. (1979). "Middle Miocene diatoms in the Hawthorn Formation Within the Ridgeland Trough, South Carolina and Georgia". Micropaleontology. 25 (3): 225, 228. doi: 10.2307/1485301. JSTOR 1485301.
- ^ USGS Florida Geology
- ^ Glen L. Faulkner, Geological Survey (U.S.), United States. Army. Corps of Engineers, Geohydrology of the Cross-Florida Barge Canal area, Tallahassee, 1973.