Bar B Formation
The Bar B Formation is a geologic formation found the Caballo Mountains of New Mexico. It preserves fossils showing it was deposited in the middle to late Pennsylvanian.[1][2]
| Bar B Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Formation |
| Underlies | Bursum Formation |
| Overlies | Nakaye Formation |
| Thickness | 339 ft (103 m) |
| Lithology | |
| Primary | Limestone, shale |
| Location | |
| Coordinates | 33.0185°N 107.2390°W |
| Region | New Mexico |
| Country | United States |
| Type section | |
| Named for | Barbee Draw (drainage) |
| Named by | V.C. Kelley and Caswell Silver |
| Year defined | 1952 |
  Bar B Formation (the United States)  Bar B Formation (New Mexico) | |
Description
The Bar B formation is mostly cyclic[2] beds of shale and limestone, with shale making up about 80% of the formation and limestone the other 20%. Chert is present in some of the limestone. The upper 50 feet (15 m) include reddish-brown siltstone, limestone conglomerate, and calcareous siltstone. The total thickness is about 339 ft (103 m).[3] The formation rests on the Nakaye Formation and is unconformably overlain by the Bursum Formation.[2]
The formation likely correlates with the Panther Seep Formation in the San Andres Mountains.[1][2]
History of investigation
The formation was first defined by V.C.Kelley and Caswell Silver in 1952.[3] Bachman and Myers criticized its definition in 1975,[1] but it is accepted by Kues and Giles, though they restrict it to the Caballo Mountains.[2]
References
- Bachman, G.O.; Myers, D.A. (1975). "The Lead Camp Limestone and its correlatives in south-central New Mexico" (PDF). New Mexico Geological Society Field Conference Guidebook. 26: 105–108. Retrieved 30 July 2020.
- Kues, B.S.; Giles, K.A. (2004). "The late Paleozoic Ancestral Rocky Mountain system in New Mexico". In Mack, G.H.; Giles, K.A. (eds.). The geology of New Mexico. A geologic history: New Mexico Geological Society Special Volume 11. pp. 95–136. ISBN 9781585460106.
- Kelley, V.C.; Silver, Caswell (1952). "Geology of the Caballo Mountains; with special reference to regional stratigraphy and structure and to mineral resources, including oil and gas". University of New Mexico Publications in Geology. 4.