505 



toward the oriental summit. The obstacles of 

 the vegetation gradually diminished ; it was 

 however necessary to cut down some heliconias ; 

 but these arborescent plants were now less 

 thick and high. The peaks of the Silla them- 

 selves, as we have several times mentioned, are 

 covered only with gramina, and small shrubs 

 ofbefaria. Their barrenness, however, is not 

 owing to their height. The limit of trees in 

 this region is four hundred toises still higher ; 

 since, judging according to the analogy of 

 other mountains, this limit would be found 

 here only at a height of eighteen hundred toises. 

 The absence of large trees on the two rocky 

 summits of the Silla may be attributed to the 

 aridity of the soil, the violence of the winds 

 blowing from the sea, and the conflagrations so 

 frequent in all the mountains of the equinoctial 

 region. 



In order to reach the eastern peak, which is 

 the highest, it is necessary to approach as near 

 as possible the great precipice, that descends 

 toward Caravalleda and the coast. The gneiss 

 as far as this spot had preserved it's lamellar 

 texture, and it's primitive direction ; but where 

 we climbed the summit of the Silla, it passes 

 into granite. It's texture becomes granular ; 

 the mica, less frequent, is more unequally spread 

 through the rock. Instead of garnets we met 

 with a few solitary crystals of hornblende . It 



