The use of vertebrate evidence for correlation in petroleum exploration is recommended. Attention is again directed to the need for a clear understanding of the difference between time, time-rock, rock, and faunal units. Six new faunal names and one new formational name are proposed. Late Eocene, early and late Oligocene, late Miocene, Miocene or Pliocene, ? Pliocene, and Pleistocene faunal units are recognized, and the faunae are listed. The late Miocene La Venta fauna is one of the largest fossil vertebrate assemblages from South America.
The report is preliminary since most of the fossils have not been described in detail, and studies on the areal geology are not complete, but there is some information on thickness of sections, sources of materials, orogenies, nature of deposition and paleoecology. A correlation chart and 11 maps and sections are included.