ON" THE GEOLOGY OF BARBADOS. 221 



subsequent elevations occurring along the same great physical lines ; 

 for marine strata more recent than the Pteropod marl are inclined 

 at a high angle, and overlain unconi'ormably by still newer marine 

 strata." 



The marine strata referred to in the last sentence are in all prob- 

 ability the lower beds of the White Limestone Series, and it would 

 appear that Mr. Barrett thought these were newer than the pteropod 

 marls, but no proof of superposition is given. The same is the case 

 with some extensive deposits of white chalky marl which occupy low 

 ground, and often abut against the White Limestone ; but the final 

 opinion of the Surveyors with respect to both these and the pteropod 

 marls seems to have been that they are post-Pliocene, or in other 

 words Pleistocene. Clearly there are many interesting questions in 

 the geology of Jamaica which are awaiting further investigation, 

 and the mutual relations of these white marls and limestones is not 

 the least important of them. 



[(d) Cuba. — W^hen this paper was read, Mr. J. W. Gregory was 

 able to announce, from the examination of rocks he had obtained 

 from Baracoain Cuba, that radiolarian earths existed in that island ; 

 he finds them to be similar in structure and mode of occurrence, and 

 also in their calcareo-siliceous varieties, to those of Barbados. — 

 Feb. 16th, 1892.] 



§ 8. Changes in the Physical Geography oe the Caribbean 

 Regiost during Tertiary time. 



In Part I. of this memoir we made some remarks on the physical 

 geography of the Caribbean region during the formation of the raised 

 coral-reefs, and we expressed our opinion that the period of upheaval 

 indicated by these reefs was preceded by a time when there was free 

 communication between the Atlantic and Pacific Oceans. It would 

 doubtless have been better if we could have presented our evidence 

 of a great submergence first and dealt with that of a subsequent 

 elevation in the second place, but circumstances obliged us to reverse 

 the natural order of things and to treat of the coral-reefs first. 



I^ow, however, that we have given the evidence for our statement 

 that the final upheaval of the region was preceded by a profound 

 submergence, we are in a position to urge our views still more 

 strongly, and we can at the same time support them with some 

 father collateral evidence. 



In considering the general question of the physical history of the 

 region during Tertiary time we are quite aware that the data at 

 present available are insufficient for anything more than an indica- 

 tion of the greater physical changes which took place in that time. 

 We are also aware that the Barbadian sequence is incomplete and 

 must be supplemented by evidence from other islands. If the 

 Scotland Beds are the equivalents of the San Fernando Beds of 

 Trinidad and if the Oceanic Series is of Pliocene age, there is an 

 unrepresented interval filled in other islands by the important group 

 of deposits which is referred to the Miocene. 



