512 PEOP. J. W. SPE]!TCER ON THE GEOLOGICAL AND [NoV. I9OI, 



namely, Orhicella cavernosa^ Linn, and 0. acropora^ Linn. — which 

 are living species, indicating an entirely different coral-fauna from 

 that of the typical Oligocene Period of the West Indies. 

 Besides the shells collected by myself, others were kindly given to 

 me by M. Louis Guesde, apparently from the same kind of rock, but 

 from unknown localities. 



Here then, at Pointe a Pitre, is a formation, in appearance 

 much like the older limestones (although more sandy and more 

 uniformly hardened into a compact rock), but far richer in fossils, 

 assignable to a different fauna. The contact of this outcrop with the 

 lower beds was not observed. Duchassaing gave a list of twenty-six 

 molluscs, thirteen echinoderms, and eight corals, as being derived 

 from his upper calcareous marl. All the corals are living, so 

 too probably most of the molluscs, but only seven of the echinoderms. 

 And he notes an abundance of polyzoa and foraminifera (Lunidites). 

 This admixture of the foraminifer Limulites (not differing from 

 L. umhellata of the Paris Basin) and extinct echinoderms, and 

 perhaps some molluscs, with forms now living, especially the corals, 

 suggests that his collections were obtained from different horizons. 

 This supposition seems probable, as his studies were centred in the 

 low district of Moule, where later deposits than even those of Pointe 

 a Pitre occur. 



From the general character of the beds at the Usine, such as the 

 consolidation of the materials into hard rocks, the complete fossili- 

 zation of the organic remains now preserved as casts, etc., and the 

 very great erosion which they have undergone since their emergence, 

 they must have a considerable antiquity. But on account of their 

 containing modern fossils, I w^ould provisionally place them at the 

 close of the Pliocene or commencement of the Pleistocene Period, 

 of nearly, if not quite, the same age as the Lafonde Series. The 

 different character of the Usine Limestones and the Lafonde 

 Series may be explained by the fact that at Lafonde the country 

 was submerged 200 feet, which still permitted of the small rocky 

 islands supplying the materials for the loams and gravels round 

 their shores ; while in deeper water and at a distance seaward from 

 the few remaining islets, the organic remains, and the sands derived 

 from them, would be the only source of supply for the rock-making 

 materials, and thus the exclusion of the fragmental remains. But 

 the Usine strata represent a deeper and longer submergence than 

 the Lafonde Marls, which have been greatly denuded.^ 



VII. Late Deposits and Cokal-Eeefs in Grande Teree. 



Raised coral-reefs occur on the eastern coast, as at Moule, up to 

 a height of 6 or 8 feet above sea-level. They contain several 



^ [From recent studies in Barbados it is now suggested that the Usine Lime- 

 stones may be either a deposit representing the continuation of the Lafonde 

 epoch, or even one subsequent to it and belonging to the earlier Pleistocene 

 period. The phenomena appear to be repeated in Anguilla, Sombrero, St. Kitts, 

 Dominica, etc.] 



