The Muzo Formation (K1m - Hauterivian-Barremian age) is a unit outcropping in the sector of Las Pavas, Peñas Blancas, and Coscuez.
A stratigraphic column, logged along the La Palma-Yacopí road and published in 2001, shows this unit is composed of a black terrigenous marl with a solid appearance with black calcareous claystone intercalations.