Discussion

Abstract

Dr K. W. B arr complimented Mr Potter on the progress of his programme regarding the elucidation of the structure and stratigraphy of the Northern Range of Trinidad, and made the following points. Firstly, in respect of the thicknesses of the formations quoted, earlier authors had postulated a variety of thicknesses ranging from a few thousand to perhaps some 30 000 feet. It was appreciated that the higher figures were based on a simpler and almost certainly erroneous structural interpretation. However, in a geosynclinal flysch series such as described, great thicknesses were quite acceptable, and it was questioned whether the thicknesses proposed by the author might perhaps err on the low side, in view of the great regional extent of this Jurassic to Cretaceous geosynclinal fore-deep. Secondly, the author had suggested that the basal Maraval limestone formation might be associated with an evaporitic series; the existence of gypsum deposits to the east of Port of Spain within the Morvant formation was well known. In their present position these are evidently a tectonic emplacement, and one wondered whether there might be some relationship at depth between the two. Thirdly, the commentator agreed that a correlation between the Morvant formation and the Galera Formation at the eastern end of the range was logical. Fourthly, regarding the contact of the Morvant formation and the Chancellor formation of the Caribbean Series, it was questioned whether this contact might be a fault plane. There are many strike faults along the southern margin of the North Range