The Tonoloway is roughly equivalent to the Salina group that is found to the north and west.

The basal 50 m consists of medium-dark-gray laminated to thin-bedded calcisiltite with shale partings and interbeds.

The remainder of the formation is cyclic, consisting of three or four resistant ledges of laminated limestone and shale.

Upper contact is conformable and undulatory, occurring at the base of the "calico" limestone of the Keyser Formation.

Relative age dating places the Tonoloway in the late Silurian.