126 J.W.SPENCER — RECONSTRUCTION OF ANTILLEAN CONTINENT. 



In Barbadoes there is an extensive capping of " raised reefs or coral 

 rocks," rising in terraces to 1,100 feet, with a thickness of from 150 to 260 

 feet, as given by Messrs Jukes-Browne and Harrison.* The contained 

 fossils are modern, except perhaps some of the corals. Although the 

 formation is elevated somewhat higher than the same deposits farther 

 westward, yet the geomorphic position, the fossils, and the magnitude 

 and character of the deposits would lead me to correlate it with the 

 Matanzas formation or the latest Pliocene ; still the epeirogenic movement 

 possibly began a little earlier on one side of the basin than the other. 

 In Guadeloupe, Anagade, and several of the northeastern Windward 

 islands fragments of the Matanzas limestone appear to exist, but they 

 have not been separated from the Miocene strata. The nucleus of the 

 Windward mass is Cretaceous or igneous, succeeded by Eocene and Mio- 

 cene strata, most of which has been removed by the stupendous denuda- 

 tion of the region during recent geologic times.f 



In Trinidad there is no corresponding calcareous formation ; but rest- 

 ing on certain deposits referred to the Miocene and unconformable to it 

 there arc the Moruga sands, and possibly some of these beds may be the 

 equivalent of the Matanzas limestone. 



Turning now to the continent, Dr Dall has mapped a large shallow 

 basin opening southward, containing a few feet of Pliocene beds. In 

 other localities only two or four feet of Miocene deposits have escaped 

 denudation. Geomorphically the upper marls with recent shells occupy 

 the same position as the Matanzas beds. The basin is such as would 

 have been formed during the Pliocene period of erosion, as already de- 

 scribed. 



If the writer be correct in the interpretation of the Antillean phenom- 

 ena the equivalent of the Matanzas formation is found in the Lafayette 

 formation of Mr W J McGee, with which the writer is familiar, over a wide 

 extent of country. The materials of the continent are essentially red or 

 yellowish loams, sands and water-worn gravels, which last occur adjacent 

 to the old waterways. On the higher lands the thickness is about 20 feet, 

 but in the valleys the writer has seenit 120 feet thick, and in the Mississippi 

 channel it is a much heavier accumulation. The formation often showed 

 no stratification where the gravel is absent. When present the gravel gen- 

 erally forms the lower part of the deposit. The materials were primarily 

 derived from the residuum of the rock decay, somewhat varied accord- 

 ing to the source, whether it was obtained from the surface remains of 



* Cited before. 



fSee Transactions of the Royal Academy of Sweden, T. ix, no. 12, 1871, where Professor P. T. 

 Cleve gives a summary of the geology of the northeastern islands of the West Indies. From his 

 pH per and other information received from unpublished sources, I should expect to find fragments 

 of both the Matanzas and Zapata formations on those islands, although perhaps the materials would 

 not be of the same constitution as elsewhere. 



