S. F. Pecliham—TJie Pitch Lake of Trinidad. 421 



have effected tliem and other formations of Trinidad, that during 

 the Cretaceous and Eocene periods there was a sea having a con- 

 siderable but variable depth of water, say up to one thousand 

 fathoms and more. It is probable that this sea extended on the 

 north to the base of the northern range of hills, a distance of 

 some twenty or twenty-five miles from the northern limit of the 

 Naparima deposits. During the Cretaceo-Eocene period the northern 

 mountains probably formed an unbroken chain with the littoral 

 Cordillera of Venezuela. This chain may be called the ' Parian 

 Kange.' According to abundantly clear evidence given by me in 

 1877,^ the great chasms between Trinidad and Venezuela called 

 the Bocas del Drago were produced by subsidence. Previous to 

 this the ' Parian Range ' probably formed the southern boundary 

 of the Caribbean continent, and was a barrier through which no 

 large river found its way. The ' Parian Range ' may be regarded 

 as one of those ' stable areas ' which has never been submerged 

 since Palceozoic times." 



"To the westward the Cretaceo-Eocene sea probably extended as 

 far as the present low-lying alluvial plains of Venezuela. In this 

 direction it was no doubt bounded by the high lands now forming 

 the Pico de Cumanacoa and the Cerro del Bergantin, ranges at 

 present twice as high as any in Trinidad. Its southern extension 

 went presumably near to the granitic and gneissic ranges and 

 plateaux of Guiana." 



" After the close of the Miocene period there was probably in the 

 region south of the ' Parian Range ' a slow and gradual upheaval 

 which brought the oceanic deposits above the level of the sea, during 

 which process they suffered great denudation. The Gulf of Paria 

 was then land, and Trinidad was then united to the mainland. At 

 that time the river Guarapiche probably flowed across Trinidad from 

 Venezuela, while the Orinoco continued to pour its waters into the 

 ocean at some distance southward. The disruption of the ' Parian 

 Range' and the formation of the Bocas and the Gulf of Paria 

 followed. There are palseontological reasons for believing that 

 this submergence did not take place until a late geological epoch." 



From this conclusion it is manifest that the Miocene period was 

 one of frequent alternation of elevation and submergence, during 

 which there were long periods when the different members of the 

 formation were covered with tropical swamps having luxuriant 

 vegetation, that are now represented by the great swamp at the 

 east end of the island. The buried vegetation of these swamps has 

 been converted into coal through Pliocene and recent times, which 

 has been distilled at low temperatures, probably initiated by fer- 

 mentation within the mass of the coal itself, assisted by the water of 

 thermal springs. 



Messrs. Wall and Sawkins discuss at length the phenomena 



peculiar to the lake, and disagree with previous observers to such 



an extent that, after a careful examination of their paper, I am 



forced to the conclusion that their study of the subject was 



^ Proc. Sci. Assoc. Trinidad, December 1877, p. 1C3. 



