The Cariblanco Formation, here named, consists of thin- to medium-bedded siltstone and sandstone that intertongues with massive conglomerate. Units of limestone, tuff, and lava in the formation are named, in order of decreasing age, the La Guaba Lava Member, the Hacienda Larga Tuff Member, the Jobo Dulce Limestone Member, the Lio Juan Limestone Member, and the Sabana Hoyos Limestone Member. Overlies the Robles Formation; underlies the Coamo Formation. Age is Late Cretaceous. The Jobo Dulce Member consists of gray, sandy, conglomeratic limestone and is present in siltstone and sandstone facies about 200 m below the top of the Cariblanco. Thickness ranges from 50 m to discontinuous.

Source: GNU records (USGS DDS-6; Reston GNULEX).