210 PITCH LAKE IN TRINIDAD. 



islands at the Bocas, consists of gneiss, of mica slate con- 

 taining great masses of quartz, and in many places ap- 

 proaching so much to the nature of talc, as to render the 

 soil quite unctuous by its decomposition, and of compact 

 bluish gray limestone, with frequent veins of white crys- 

 tallized carbonate of lime. From the foot of these mount- 

 ains for many leagues to the southward there is little else 

 than a thick, fertile, argillaceous soil, without a stone or a 

 single pebble. This tract of land, which is low and per- 

 fectly level, is- evidently formed by the detritus of the 

 mountains, and by the copious tribute of the waters of the 

 Orinoco, which, being deposited by the influence of currents, 

 gradually accumulates, and in a climate where vegetation 

 is astonishingly rapid, is speedily covered with the mangrove 

 and other woods. It is accordingly observed, that the 

 leeward side of the island constantly encroaches on the 

 gulf, and marine shells are frequently found on the land, 

 at a considerable distance from the sea. This is the cha- 

 racter of Naparima and the greater part of the country I 

 Land formed saw along the coast to la Crave. It is not only in forming 

 bytheOronoka d extendin the CO ast of" Trinidad, that the Orinoco 



and the river of ° ' 



Amazons. exerts its powerful agency; cooperating with its mighty 

 sister flood, the Amazons, it has manifestly formed all that 

 line of coast and vast extent of country, included between 

 the extreme branches of each river. To use the language 

 of a writer in the Philosophical Transactions of Edinburgh, 

 " If you cast your eye upon the map you will observe, 

 " from Cayenne to the bottom of the gulf of Paria, this 

 ** immense tract of swamp formed by the sediment of these 

 " rivers, and a similar tract of shallow muddy coast, which 

 " their continued operation will one day- elevate. The 

 *' sediment of the Amazons is carried down thus to leeward 

 ft (the westward) by the constant currents which set along 

 " from the southward and the coast of Brazil. That of the 

 M Orinoco is detained and allowed to settle near its 

 *' mouths by the opposite island of Trinidad, and still more 

 " by the mountains on the main, which are only separated 

 f from that island by the Bocas del Drago. The coast of 

 " Guinea has remained, as it were, the great eddy or resting 

 " place for the washings of great part of South America 



" for 



