| Arroyo Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Formation |
| Unit of | Clear Fork Group |
| Underlies | Vale Formation |
| Overlies | Waggoner Ranch Formation |
| Thickness | 250 ft (76 m) |
| Lithology | |
| Primary | Limestone, mudstone |
| Other | Gypsum |
| Location | |
| Coordinates | 33°48′N 99°12′W / 33.8°N 99.2°W |
| Approximate paleocoordinates | 0°24′N 29°36′W / 0.4°N 29.6°W |
| Region |  Texas |
| Country |  United States |
| Type section | |
| Named for | Los Arroyos, Runnels County, Texas |
| Named by | Beede & Waithe |
| Year defined | 1918 |
  Arroyo Formation (the United States)  Arroyo Formation (Texas) | |
The Arroyo Formation, sometimes termed the Lower Clear Fork Formation, is a geologic formation in Texas.[1] It preserves fossils dating back to the Kungurian stage of the Permian period.[2] It is the lower-most portion of the Clear Fork Group, part of a series of fossiliferous Permian strata in the south-central United States known as the red beds.
- ^ Arroyo Formation at Fossilworks.org
- ^ Lucas, Spencer G. (2018). "Permian tetrapod biochronology, correlation and evolutionary events". Geological Society, London, Special Publications. 450 (1): 405–444. Bibcode:2018GSLSP.450..405L. doi:10.1144/SP450.12. ISSN 0305-8719. S2CID 134768451.