by R. M. Stainforth
Attention is drawn to a short article which may have escaped general notice, namely “Some Tertiary fossils from the Goajira Peninsula of Colombia” by Axel A. Olsson and Horace C. Richards, 1961. Short faunal lists are given from three localities, two determined as Upper Oligocene and the third as Upper Eocene. The fossils were collected during field studies by the Conorada Petroleum Company.
Brief comments on the Upper Eocene locality seem justified. The fauna consists of only two specimens of a pelecypod identified as Venericor Hornii (Gabb) subsp. with some affinities to V. samanensis Olsson. The description and figures appear to match specimens known from outcrops around Flor de Guajira in the southeast part of the Peninsula. It is a large species with 18 to 20 ribs which are bold, rectangular in cross section, and well separated in the umbonal region, but become broader and flatter towards the margin, where they are separated only by deep grooves.
O. Renz (1960, p. 336, 337) in a report based on Shell field studies in the Guajira, refers these outcrops to the Paleocene Guasare formation, and mentions well preserved Venericardia cf. planicosta Lamarck as evidence of their age. However, G. H. Fraunfelter of Creole examined these Shell specimens in 1956 and determined the pelecypods as a new species with certain affinities to Venericordia (Venericor) austroplata Gardner and Bowles from the Upper Eocene of Argentina, associated with Turritella sp., cf. T. chira. He considered the age Upper Eocene, not Paleocene. Later, during 1957, J. Black of Creole collected fossils from the Flor de Guajira area and Fraunfelter again determined the faunas as Upper Eocene in addition to the same Venericor sp. he noted Ostrea sp. aff. O. restinensis Olsson, Pitar (Lamelliconcha) sp., cf. P. (L.) eocenica Weaver and Palmer and Turritella sp., cf. T. arenicola (Conrad). The age determination by Olsson and Richards appears to confirm Fraunfelter’s unpublished opinions.
The geologic sub-committee of the First Venezuelan Petroleum Congress has prepared a revised stratigraphic chart of Venezuela (in press) on which the Guajira column indicates the Venericardia-bearing unit at Flor de Guajira as the “Macarao formation” of Upper Eocene age. The unnamed orbitoidal beds described by O. Renz (loc. cit.) are shown as a separate Upper Eocene unit, named “Nazaret Formation” on the chart.
The most striking feature of the Upper Eocene fossils described by Olsson and Richards is their locality. This is described as “about 11 kilometers northeast of Uriba”. In a personal communication Dr. Ben F. Uhl, president of Conorada, has kindly confirmed that this is a misprint for Uribia, and furthermore indicates that the locality is almost due north, not northeast, of the town. Uribia is in the southwest sector, on the neck of the Peninsula and the reported fossil locality is about 100 kilometers west of the Flor de Guajira outcrops (Macarao Formation). Hitherto it has been thought that the Upper Eocene sea only invaded the easternmost edge of the Peninsula. O. Renz (loc. cit.) has expressed this concept succinctly, and to the writer’s knowledge it is the general opinion among geologists who know the area. Consequently it is a surprise to find marine Upper Eocene recorded far to the west. Unfortunately Olsson and Richards give no supporting field data, and do not specifically state that the two Upper Eocene pelecypods were collected in situ.