GEOLOGY OF THE DISTRICT. 185 
that join the Apure and the Orinoco from those that 
flow into the Caribbean Sea or the Lake of Valen- 
cia. On this ridge are built the towns of Nirgua, 
San Felipe, Barquesimeto, and Tocuyo. The ground 
rises toward the south. 
In the cordillera just described, the strata usual- 
ly dip to the N.W.; so that the waters flow in that 
direction 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 Maracaybo. 
Of the streams that descend N.E. toward the coast 
of Porto Cabello and La Puenta de Hicacos, the 
most remarkable are the Tocuyo, Aroa, and Tara- 
euy ; the valleys of which, were it not for morbid 
miasmata, would perhaps be more populous than 
those of Aragua, as the soil is prolific and the waters 
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 ewts. of excellent metal. 
Indications of silver and gold have been found in 
various parts. 
The Savannahs 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 
sulphuretied hydrogen gas. 
