GEOLOGY OF THE DISTRICT. 159 



a chain of hills, which separates the rivers that join 

 the Apure and the Orinoco from those that flow 

 into the Caribbean Sea or the Lake of Valencia. 

 On this ridge are built the towns of Nirgua, San 

 Felipe, Barquesimeto, and Tocuyo. The ground 

 rises towards the south. 



In the cordillera just described, the strata usually 

 dip to the N. W ; so that the waters flow in that di- 

 rection over the ledges, forming those numerous 

 torrents and rivers, the inundations caused by which 

 are so fatal to the health of the inhabitants from 

 Cape Codera to the Lake of Maraycabo. 



Of the streams that descend N.E. towards the 

 coast of Porto Cabello and La Puenta de Hicacos, 

 the most remarkable are the Tocuyo, Aroa, and Ta- 

 racuy ; the valleys of whicl? were it not for morbid 

 miasmata, would perhaps be more populous than 

 those of Aragua, as the soil is prolific and the wa- 

 ters navigable. In a lateral valley, opening into that 

 of the Aroa, are copper-mines ; and in the ravines 

 nearer the sea are similar ores and gold- washings. 

 The total produce of both amounts to a quantity 

 varying from 1087 to 1358 cwts. of excellent metal. 

 Indications of silver and gold have been found in 

 various parts. 



The savannas or llanos of Monai and Carora, 

 separated from the great plains of Portuguesa and 

 Calabozo by the mountainous tract of Tocuyo and 

 Migua, although bare and arid, are oppressed with 

 miasmata ; and Humboldt seems to think that their 

 insalubrity may be owing to the disengagement of 

 sulphuretted hydrogen gas. 



