It has a radiometric age of 34.6 to 26.9 million years, corresponding to the late Eocene through Oligocene epochs.

A basalt flow at the base of the overlying Tanos Formation has an age of 25.1 +/-0.6 Ma.

The formation crops out in the Hagan and Galisteo Basins and the La Cienega area of New Mexico.

[2] The formation is also found in the subsurface in the southern Espanola Basin, where it was deposited on the eroded surface of a now-buried block of crust that was uplifted during the Laramide orogeny and thrown back down with the opening of the Rio Grande rift.

[4] The paleomagnetism of the formation has been closely studied, with one study indicating that the block of crust on which the formation was deposited subsequently experienced a counterclockwise rotation of 17.8° ± 11.4°, due to opening of the Rio Grande Rift,[5] but another showing no such rotation.