Bar B Formation
Geologic formation in New Mexico, US
From Wikipedia, the free encyclopedia
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]
Fossils
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]
