OF SANTO DOMINGO. 



163 



entire thickness of the formation undisturbed on their upturned edges. Most of this 

 has since been denuded away, but Isabella de Torres still remains, an ancient beach- 

 mark, its level top of white limestone 2,530 feet above the sea. This is the only case 

 where the entire thickness of the Miocene can be estimated by a vertical section. But 

 unfortunately the flanks of Isabella are so covered up by talus that the only rock 

 accessible in place is the cap of hard limestone. Deducting the probable elevation 

 of the cretaceous base, the thickness is approximately 2,000 feet, or a trifle over my 

 estimate in the theoretical section given elsewhere. If, however, we were to take the 

 thickness of every member of the formation where it is most freely developed, we 

 could run up the figures much higher than 2,000 feet. My object was rather to give 

 a reasonable average. 



The above deductions will, I believe, be found to be fully warranted by a con- 

 sideration of the details of the range as developed by the half dozen sections which I 

 have made across it. For the accuracy of my observations, where my statements 

 differ from those of my predecessor, whether in this case or in my preceding descrip- 

 tion of the adjoining valley, I must simply beg the indulgence of the reader, remind- 

 ing him that I can have no object in disparaging the labors of a dead man whom I 

 never saw, and that I commenced my work and carried it on with a full knowledge 

 of his published account of the region. A due regard for truth and for my own 

 reputation as a geological observer oblige me occasionally to contradict his assertions 

 but I do so in no spirit of antagonism — rather with a feeling of regret that so in- 

 experienced an observer should have been tempted to " rush into print." I make this 

 statement to clear myself of any unfair imputations and to avoid future discussion of 

 the subject with any of his surviving friends, should such exist. 



Monte Cristi, the extreme western point of the northern range, is a narrow flat- 

 topped hill a trifle over 800 feet high, entirely isolated from its neighbors by a broad 

 belt of salt marsh cut through by tidal creeks communicating with the sea. Its 

 summit is capped with a hard limestone containing foraminifera, and which has im- 

 peded to some extent the action of the denuding agencies which separated it from the 

 main ridge. This limestone has so completely resisted atmospheric influences that 

 its surface is nearly naked. Possibly its puritv is so great that it is all soluble, and 

 unhke the coast limestone, it contains too little aluminous matter to leave any soil after 

 the lime is dissolved by the rains. Whatever be the reason, the dense crest of thoi'ny 

 bushes which it bears finds nourishment only in the crevices where a soil so scanty 

 as hardly to merit the name has accumulated. Below the limestone the Guavubin 

 shales come in, their upper part pebbly like near Santiago and Angostura. These 



