| Bar B Formation | |
|---|---|
| Stratigraphic range: middle Pennsylvanian–late Pennsylvanian PreꞒ Ꞓ O S D C P T J K Pg N | |
| Type | Formation |
| Underlies | Bursum Formation |
| Overlies | Nakaye Formation |
| Thickness | 339 ft (103 m) |
| Lithology | |
| Primary | Limestone, shale |
| Location | |
| Coordinates | 33°01′07″N 107°14′20″W / 33.0185°N 107.2390°W / 33.0185; -107.2390 |
| 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)Show map of the United States Bar B Formation (New Mexico)Show map of New Mexico | |
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.
Description
The Bar B formation is mostly cyclic 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). The formation rests on the Nakaye Formation and is unconformably overlain by the Bursum Formation.
The formation likely correlates with the Panther Seep Formation in the San Andres Mountains.
Fossils
The formation contains abundant bryozoan fossils.
History of investigation
The formation was first defined by V.C.Kelley and Caswell Silver in 1952. Bachman and Myers criticized its definition in 1975, but it is accepted by Kues and Giles, though they restrict it to the Caballo Mountains.
See also
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.