Drs. O. Renz, H. Hubach, and A. Gansser, geologists of the Cia. de Petroleo Shell de Colombia, have collected several small faunas of Paleozoic and Early Mesozoic age during the past few years. Some of these faunas are new, while the others give additional information on the distribution of the pre-Cretaceous formations in Colombia.
The basement rocks of the Macarena are briefly described. Cambro-Ordovician graptolite and trilobite faunules were found in the Macarenas and near Colombia, a small village about 80 kilometers northeast of Neiva. On the Colombian side of the Sierra de Perija, Devonian beds with a Floresta fauna overlap with sharp, angular unconformity upon slightly metamorphosed shale. Small Carboniferous faunas were collected on Cerro Cerrejón in the Rancheria valley, at Bucaramanga, and at Labateca. A good Leonard fauna was found near Manaure in the Sierra de Perija, and boulders of Permian Fusulina limestones occur in red beds near Chiriguaná. Marine Upper Triassic limestones are normally interbedded with porphyritic red beds at Payande near Ibague. Probably also of Upper Triassic age are black shales with Estheria exposed on the road between Duitama and Charala and in Quebrada de los Indios about 25 kilometers south of Fundación.
Black shales and limestones underlying red beds and porphyrites have recently furnished ammonites of Lower Liassic age at a locality on Laguna Morrocoyal southwest of El Banco. Some granites and porphyrites of the Cordillera Central are post-Liassic.