Spears Group
| Spears Group | |
|---|---|
| Stratigraphic range: Eocene to Oligocene | |
Dog Springs Formation in the Sawtooth Mountains of New Mexico | |
| Type | Group |
| Sub-units | See text |
| Underlies | Fence Lake Formation Hayner Ranch Formation |
| Overlies | Baca Formation |
| Thickness | 3,000 ft (910 m) |
| Lithology | |
| Primary | Volcaniclastics |
| Other | Andesite |
| Location | |
| Coordinates | 34°16′52″N 107°17′46″W / 34.281°N 107.296°W |
| Region | New Mexico |
| Country | United States |
| Type section | |
| Named by | Tonking |
| Year defined | 1957 |
The Spears Group is a group of geologic formations exposed in and around the northeast Mogollon-Datil volcanic field of southwestern New Mexico. It has a radiometric age of 33 to 39 million years, corresponding to the Eocene to Oligocene epochs.