The formation consists of calcareous shales and siltstones and dates to the Early Cretaceous period; Late Aptian epoch and has a measured thickness at its type section of 381 metres (1,250 ft).

Ammonite fossils have been found in the formation, deposited in a shallow marine platform environment.

The formation was defined and named in 1982 by Ulloa after El Peñón, Cundinamarca.

[1] The El Peñón Formation has at is type section a thickness of 381 metres (1,250 ft),[2] and is characterised by a sequence of calcareous shales and siltstones.

[1] In the Late Aptian, central Colombia was dominated by shallow marine carbonate platform environments.