Bloyd Formation
Geologic formation in Arkansas, United States
From Wikipedia, the free encyclopedia
The Bloyd Formation, or Bloyd Shale, is a geologic formation in Arkansas. It preserves fossils dating back to the Carboniferous period.
TypeFormation
Sub-unitsBaldwin coal,[1] Brentwood Member, Dye Shale Member, Kessler Limestone Member, Parthenon Sandstone Member,[2] and Woolsey Member[3]
UnderliesAtoka Formation
OverliesHale Formation
| Bloyd Formation | |
|---|---|
| Stratigraphic range: Pennsylvanian | |
Fossil from the Bloyd Formation | |
| Type | Formation |
| Sub-units | Baldwin coal,[1] Brentwood Member, Dye Shale Member, Kessler Limestone Member, Parthenon Sandstone Member,[2] and Woolsey Member[3] |
| Underlies | Atoka Formation |
| Overlies | Hale Formation |
| Lithology | |
| Primary | Shale |
| Other | Sandstone, limestone |
| Location | |
| Region | Arkansas |
| Country | United States |
| Type section | |
| Named for | Bloyd Mountain, Washington County, Arkansas[4] |
| Named by | Albert Homer Purdue |
Stratigraphy
The Bloyd Formation conformably overlies the Hale Formation and unconformably underlies the Atoka Formation. Five formal and one informal members are recognized in the Bloyd Formation (in stratigraphic order):
- Kessler Limestone Member
- Dye Shale Member
- Parthenon Sandstone Member (also known as the "middle Bloyd sandstone")[5]
- Woolsey Member
- Baldwin coal (an informal unit at the top of the Woolsey Member)
- Brentwood Limestone Member
In the eastern parts of the Ozarks in Arkansas, the Bloyd Formation becomes undifferentiated with the underlying Hale Formation and is called the Witts Springs Formation.
Paleontology
Brachiopods
Bryozoans
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Cephalopods
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Conodonts
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Crinoids
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Flora
- A. missouiense[13]
- Cuneiphycus
- C. aliquantulus[13]
- Donezella[13]
- Eflugelia[13]
- Girvanella[8]
- G. minuta[13]
- Paraepimastopora[13]
- Stachedoides
- S. spissa[13]
Foraminifera
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Ostracods
- Bairdiolites[15]
- Hollinella
- H. bassleri[14]
- Pseudoparaparchites[15]
Sponges
- Haplistion
- H. sphaericum[16]
- Steioderma
- S. hadra[16]
- Virgaspongia
- V. ichnata[16]
Trace Fossils
- C. arkansanus[17]
Incertae sedis
- Asphaltina
- A. cordillerensis[13]
- Clacisphaera
- C. laevis[13]
- P. strigosa[13]
