l34 DESCENT RAVINE OF TlPE. 



now and then obscured by clouds. The guides who 

 carried the instruments shmk off successively to 

 sleep among tlie cliffs ; and it was not until ten that 

 the travellers arrived at the bottom of the ravine, 

 overcome by thirst and fatigue. 



During the excursion to the Silla, and in all their 

 walks in the valley of Caraccas, they were very at- 

 tentive to the indication of ores which they found in 

 the gneiss mountains. In America that rock has not 

 hitherto been found to be very rich in metals ; the 

 most celebrated mines of Mexico and Peru bemg ni 

 primitive and transition slate, trap, porphyry, gray- 

 wacke, and alpine limestone. In several parts of 

 the region now visited, a small quantity of gold was 

 found disseminated in veins of quartz, sulphuretted 

 silver, blue copper-ore, and leadglance ; but these 

 deposites did not seem of any importance. In the 

 group of the western mountains of Venezuela the 

 Spaniards, in 1551, attempted the gold mine of Buria, 

 but the works were soon given up. In the vicinity 

 of Caraccas some had also been wrought, but to no 

 great extent. In short, the mines here afforded 

 little gratification to the cupidity of the conquerors, 

 and were almost totally abandoned ; those of Arva, 

 near San Felipe el Fuerte, being the only ones in 

 operation when Humboldt visited the country. 



In the course of their investigations the travellers 

 examined the ravine of Tipe, situated in that part 

 of the valley which opens towards Cape Blanco. 

 The first portion of the road was over a barren and 

 rocky soil, on which grew a few plants of Ar- 

 gemone Mcxicana. On either side of the defile was a 

 range of bare mountains, and at this spot the plain 

 on which the town is built communicates with the 

 coast near Catia by the valleys of Tacagua and 

 Tipe. In the former they found some plantations 

 of maize and plantains, and a very extensive one of 

 cactuses fifteen feet high. They met Avith several 



