The sequence of pyrite containing dark grey micaceous shales interbedded with siltstones and sandstones dates to the Ordovician period; Middle to Late Floian epoch, and has a maximum thickness of 670 metres (2,200 ft) in the type section.

The graptolites are mostly found in the silty beds and indicative of a fair weather environment on a siliciclastic shallow marine platform at the northern edge of Gondwana.

The shallow sea where the Venado Formation was deposited ranged into the deeper cold Iapetus and Rheic Oceans, separating the South American continent of the time from Laurentia, Avalonia and Baltica.

The formation, part of the Agua Blanca Group,[3] crops out on both banks of the Venado River in El Totumo, a vereda of the municipality Baraya in the department of Huila.

[6][7] The Venado Formation comprises laminated dark grey micaceous shales, with intercalating siltstone levels and very fine sandstone beds.

The siltstone layers contain fragmented fossils of graptolites and are probably indicative of a fair weather environment and the coarser sediments resulted from episodic and rhythmic storms.