Earth:Nashua Formation
| Nashua Formation Stratigraphic range: early Pleistocene | |
|---|---|
| Type | Formation |
| Location | |
| Region | Florida |
| Country | United States |
| Type section | |
| Named for | Nashua on St. Johns River |
The Nashua Formation is an early Pleistocene geologic formation in Florida. The fine to coarse quartz sands, fossiliferous quartz sands, and dark clays contain wood and brackish-water fossils.[1]
It is a nearshore marine formation that occurs in a band 40 to 70 km wide along the Atlantic Coast of Florida.[1]
Background
This is described as variably calcareous, shelly sand, and finely sandy shell coquina.[1]
Deposited in open-marine, shallow-water on an inner neritic continental shelf. Underlies the St. Johns River area at least as far south as Deland, Volusia County.[1]
Location
The formation's northern limit is in the vicinity of the St. Marys River and so it probably also occurs in Georgia. It grades westward and northward into the Cypresshead Formation.
The area overlies the Coosawhatchie Formation and underlies only undifferentiated surficial sand deposits in northeast Florida.
In the coastal area, it may be overlain by the Satilla Formation. The formation was measured in a well at Deland at 32 ft (10 m). The formation is probably a multi deposit formation.[1]
Age
On the basis of foraminifera found, the unit was assigned an age range of late Pliocene to early Pleistocene.[1]
Organisms
Barnacles, bryozoans, coral, crab claws, sand dollars and sea urchin spines have been found in this formation.[2]
See also
- List of fossiliferous stratigraphic units in Florida
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 "Geologic Unit: Nashua". https://ngmdb.usgs.gov/Geolex/UnitRefs/NashuaRefs_2944.html#:~:text=Nearshore%20marine%20Nashua%20Formation%20occurs,wood%20and%20brackish%2Dwater%20fossils.. Retrieved 18 November 2020.
- ↑ Rubin, Harry E.; Visaggi, Christy C.; Bash, Jennifer G.; Clinton, John Michael; Freeman, Jennifer R.; Golden, Lawrence S.; Hill, Ashley M.; Toro, Matthew J. et al. (2019). Taphonomy, Bioerosion, Encrustation, and Paleoenvironmental Reconstruction of Molluscan Assemblages from the Plio-Pleistocene Nashua Formation of Northern Florida. Geological Society of America Abstracts with Programs. doi:10.1130/abs/2019SE-326725.
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