TEETIAEY MICKOZOIC FORMATIONS OF TRINIDAD. 537 



regarded as one of those "stable areas" which have never been 

 submerged since Palaeozoic times. Volcanic action seems to have 

 been limited to the northern side of it, for volcanic matter only 

 appears in minute quantity in the Trinidad deposits. The area 

 south of the Parian Eange, including Trinidad and the Gulf of Paria, 

 has never at any time been a volcanic area nor have any volcanic 

 or plutonic rocks been discovered therein. Eeyond the minute 

 quantity of volcanic debris just referred to, the only substance 

 attributable to a volcanic origin I have met with has been a pebble 

 or two of a trap-like rock in one of the ancient river-beds of the 

 island. 



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 land 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. The Orinoco was at this time in existence, but 

 although its waters flowed over and modified the tinge of the upper 

 strata of the ocean, keeping out some of the pelagic forms of life, 

 as is now the case to the north of Trinidad as far as Tobago and 

 Grenada, yet they brought no appreciable sediment so far from what 

 was then the mouth of the river. The main current must then 

 have run more directly towards the east in the line of what is still 

 the principal channel of the river, 100 miles or more south of 

 Trinidad. The intermediate sea acted as a settling-pond, as the 

 Gulf of Paria does now for those branches of the Orinoco which 

 pour their turbid waters into it. Eastward the Cretaceo-Eocene 

 sea was fully open to the Atlantic. 



To what distance northward our supposed continent extended it 

 is not easy to deduce from the facts now at hand, or what connexion 

 it had with the existing islands. Along the northern coast of Vene- 

 zuela there is a considerable belt of shallow water not exceeding a 

 depth of about 50 fathoms. And this shallow sea is full of rocks, 

 shoals, and islands. But beyond this the depth of water increases 

 greatly, and hence the difficulty of accepting what, at first glance, 

 appeared a likely conclusion, namely, that the Caribean Sea was 

 formerly the site of a continent of which the former margins are in 

 part indicated by the islands of the Antilles. 



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 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 

 Eange and the formation of the Bocas and the Gulf of Paria probably 

 followed ; and these events may have been contemporaneous with 

 the submergence of the Caribean land. There are palseontological 



