Geologic-stratigraphic background

This section deals with the Middle Cretaceous (Late Albian) to Early Eocene benthic foraminifera of Central and South Trinidad. This time interval includes, from bottom to top, the Gautier, Naparima Hill, Guayaguayare and Lizard Springs formations, as defined in the Stratigraphic Lexicon of Trinidad (Kugler 1956). Their position within the stratigraphic framework of the southern Caribbean area is shown on the regional correlation charts (Fig. 2 and Fig. 3). This complex of four formations consists of a marine sequence of calcareous to argillaceous rocks which has a compound thickness of approximately 1500 metres; its actual thickness, however, may vary considerably due to local or regional hiatuses and/or tectonic disturbances. It lies above a Lower Cretaceous group of formations, of which the youngest is the Maridale Formation (Late Aptian-Early Albian) and is, in turn, overlain by the Navet Formation (mostly of Middle to Late Eocene age). The underlying and overlying formations form the subject of the preceding and the following chapter, respectively, of this volume.

The rocks which nowadays represent the Gautier, Naparima Hill, Guayaguayare and Lizard Springs formations have for a long time been known from relatively small and isolated surface outcrops such as those described by Wall & Sawkins (1860), Waring (1926), Liddle (1928; 2nd edition 1946), Jarvis (1929) and Skelton (1929). These authors have reported various megafossils, usually indicative of a Cretaceous age. Gradually, attention was also focussed on micro-fossils, usually foraminifera, particularly since the pioneer papers on the Lizard Springs area by Cush-man & Jarvis (1928, 1932).