ON THE GEOLOGY OF THE NORTH-EASTERN WEST-INDIA ISLANDS. 41 



dOrbigny has published some illustrations belong partly to still living species and partly 

 to extinct forms, found also in the miocene rocks of Anguilla and Puerto Rico. In the 

 island of Cuba, too, an elder formation occurs, containing syenite associated with serpen- 

 tine, basaltic rocks and brown saccharoid lime-stone. That formation is remarkable for 

 the occurrence of very rich metalliferous veins*) and bituminous coal. The age of this 

 formation, in which no fossils are found, is unknown. 



Jamaica**). The geology of this large island is far better known than the geology 

 of the other West-India islands. We are especially indebted for our knowledge of the 

 island to Mr. Barrett, whose early decease was unfortuuately a great loss to science. 



The oldest fossiliferous rocks of Jamaica belong to the cretaceous formation. They 

 are visible in the eastern part, near Bath, as well as in the interiör of the island in the 

 Clarendon district. The fossiliferous rocks rest upon igneous conglomerates and por- 

 phyries. They are very disturbed strata, sometimes almost verticaJ, sometimes raised at 

 an angle of 40°— 50°. The strata consist of compact limestones, shales etc. Among the 

 fossils are Nerincea, Acteonella Iwvis d'Orb, Orbitoides and Eudistes (Barettia Monilifera 

 Woodw). The formation is believed to be an equivalent to the European »Turonien». To 

 judge from the description, the petrographical character of the rocks seems to have a great 

 resemblance to that of the rocks of the Virgin-Islands. The eocene formation of Jamaica 

 is well developed and it forms beds of 1,000 meters in thickness. The rocks of the lower 

 part of the eocene formation are porphyritic conglomerates, and in the upper part shaly 

 and sandy beds occur. Some fossils are found in the upper part, and among thern some 

 corals, known from the eocene beds of the old world. It seems probable, that the eocene 

 formation of Jamaica dates from the more ancient part of that time. 



The greatest portion of the surface of Jamaica is covered by a härd and white 

 limestone-rock, at least 600 meters thick. It contains only few fossils and rests in some 

 parts unconformably and in others conformably upon strata of about 200 meters in thick- 

 ness. The latter beds consist of sand, marls or various calcarious rocks and contain a 



*) Descriptions of these veins are given by Mr Ansted Quart Journ. Geol. Soo. Vol. 12, 1856 p. 144. 

 **) Papers published on the geology of Jamaica and of which I am cognizant, are: 



1827 H. de la Beche. Remarks on the geology of Jamaica Transact, Geol. Soc. of Lond. II Ser Vol. 

 II, part II, p. 143—195. 



1856 A. S. Orsted. Skildring af naturen paa Jamaica (Tidskrift for populsere framstillingar of natur- 

 videnskaben p. 80). 



1860 Barrett. On some cretaceous rocks in the south eastern portion of Jamaica. Quart. Journ. 

 Geol. Soc. Vol. 16 p. 324. 



1862 Sawkins. On the association of grauite with Tertiary strata near Kingston, Jamaica. Quart. 

 Journ. Geol. Vol. 19 p. 35. 



1863 Carrick Moore. On some Tertiary Shells from Jamaica with a note on the corals by P. Martin 

 Dtjncan and a note on some nummulinse and orbitoides by R. Jones. Quart. Journ Geol. Soc. Vol. 19 

 p. 510. 



1864 Duncan and Wai.l. »A notice of the Geology of Jamaica etc." Quart. Journ. Geol. Soc. Vol. 

 21 p. I. 



1866 Guppy on the tertiary mollusca of Jamaica. Quart. Journ. Geol. Soc. Vol. 22 p. 281. 



K. Vet.-Akad. Handl. B. 9. N:o 12. O 



