124 GKOLOGY OF THE DISTRICT. 



CHAP. XI. table-land covered with Aljiine plants ; and here is seen 

 for the first time the capital, standing nearly 2000 feet 

 lower, in a beautiful valley enclosed by lofty mountains. 



AviiUu xhe ridges between La &uayra and Caraccas consist 



of gneiss. On the south side, the eminence which bears 

 the name of Avilla is traversed by veins of quartz, con- 

 taining rutile titanite in prisms of two or three lines in 

 diameter. The gneiss of the intervening valley contains 

 red and green garnets, which disappear when the rock 

 passes into mica-slate. Near the cross of La Guayra, 

 half a league distant from Caraccas, there were vestiges 

 of blue copper-ore disseminated in veins of quartz, and 

 small layers of graphite. Between the former point 

 and the spring of Sanchorquiz were beds of bluish-gray 

 primitive limestone, containing mica, and traversed by 

 veins of white calcareous spar. In this deposite were 

 found crystals of pyrites and rhomboidal fragments of 

 sparry iron-ore. 



