344 PEOCEEDINGS OP THE GEOLOGICAL SOCIETY. [JuHG 9, 



At the distance of fifteen miles or so from the river, the land rises 

 into scarped, low, more or less wooded heights, constituting the 

 serranos, interspersed with grassy slopes and plains. These ser- 

 ranos by easy gradations lead ns on to the range of the Itacama 

 Mountains, which trend east and west and attain an elevation of 

 about 3000 feet. The range occupies a breadth of about sixty miles ; 

 and its southern slope is bounded by an undulating grassy plain 

 presenting an aspect similar to that of the Llanos, excepting that 

 woodlands occupy the margins of the streams, and that a species 

 of palm grows on the moister portions of the soil. This plain, 

 the mean elevation of which is about 800 feet above the sea- level, 

 stretches southward as far as the river Yuruari, which marks off the 

 savannah from the forest-region of the Caratal, the subsoil of which is 

 a ferruginous clay affording firm attachment for timber trees of 

 large growth. The Caratal district, so far as it is known, is broken 

 up into ridges and peaks of about 1500-2000 feet elevation, with 

 narrow and deep dividing valleys. 



It is to be observed that the Itacama Mountains divide the eastern 

 part of Yenezuelan Guyana into two hydrographical basins, to the 

 north that of the Orinoco, and to the south that of the Essequibo, 

 which by its tributary, the Cuyuni, and its numerous affluents 

 drains the country to the south of the Itacama range, and to the 

 east of the basin of the Caroni. 



II. Geology op Noeth-east Venezuela. — Mr. Wall*, in his 

 " Geology of a Part of Yenezuela," has described the geological 

 features of a portion of Yenezuela to the north of the Orinoco ; and, 

 so far as I can judge by reading his account, the arrangement and 

 nature of the rocks in the district to the south of the river seem to 

 concur in a great measure with those to the north. 



That author has established the existence : — First, of a series of 

 micaceous and siliceous schists, with interbedded crystalline lime- 

 stones ; and in a few restricted localities the schistose beds alternate 

 with gneiss. This group of metamorphic rocks, to which he has 

 assigned the term Caribbean, exhibits great disturbance and contor- 

 tion; the strike is ordinarily east and west; the metalliferous 

 minerals are gold disseminated in gneiss west of Yalencia, a sulphuret 

 and carbonate of copper in the schists at Las Teques, near Caracas, 

 and argentiferous galena near Carupano. Secondly, of neocomian 

 strata overlying the schistose rocks to the south; and, thirdly, of an 

 arenaceous series belonging to the upper miocene, and termed newer 

 Parian by the author, which overlies and abuts against the neoco- 

 mian rocks. In Yenezuelan Guyana, the metamorphic series and the 

 upper miocene strata are developed, but neocomian beds have not 

 been observed. 



III. Metamorphic Seeies op Yekezfelan Guyana. — The section 

 attached (fig. 1) will suffice to show the regularity of the bedding, 

 and the somewhat undisturbed conditions, of this series. The trend is 

 usually east and west, and coincides with that of the Caribbean system 

 of Northern Yenezuela; the dip is from 70°- 75°, to the north ordinarily; 



* Quart. Journ. Geol. Soc. vol. xvi. p. 460 et seq. 



