[2] It is of interest to geologists for the clues it preserves of the nature of Laramide deformation in the latest Cretaceous.

[3] The formation is mostly basalt[4] or andesite[5] lava flows, but with some interbedded breccia and pyroclastic rock and, in some locations, up to 200 feet (61 m) of limestone and shale.

[4] Argon-argon dating gives a consistent age between 70.53 and 71.44 million years.

[6] The formation is interpreted as a volcanic center located inland of the southwest coast of the Ringbone depositional basin[4] that erupted during Laramide tectonic deformation that partitioned the basin.

[8] It may correlate with the Salero Formation of southeastern Arizona.