138 



to the missionaries against the persecutions of 

 a warlike chief of the Tuacopans, encamped on 

 the banks of the river Caripe. 



Before we quit the subterraneous rivulet and 

 the nocturnal birds, let us cast a last glance at 

 the cavern of Guacharo, and the whole of the 

 physical phenomena it presents. When we have 

 followed the traveller step by step, in a long 

 series of observations modified by the localities 

 of a place/ we love to stop, and raise our views 

 to general considerations. Do the great cavi- 

 vities, which are exclusively called caverns, owe 

 their origin to the same causes, as have pro- 

 duced the lodes of veins and of metalliferous stra- 

 ta, or the extraordinary phenomenon of the 

 porosity of rocks ? Do grottoes belong to every 

 formation, or to that period only, when organized 

 beings began to people the surface of the globe ? 

 These geological questions can be solved only 

 so far as they have for their object the actual 

 state of things, that is, of facts susceptible of 

 being verified by observation. 



Considering rocks according to the succession 

 of eras, we find, that the primitive formations 

 exhibit very few caverns. The great cavities, 

 which are observed in the oldest granite ; and 

 which are called jours [ovens] in Switzerland, 

 and in the South of France, when they are lined 

 with rock crystals ; arise most frequently from 

 the union of several contemporareous veins of 



