Geological Delineation of South America. 175. 



the Oucbrada de Catia, the alum ore of Chiiparuparu, some 

 traces of iron ore in the llano of St. Sebastian, and par- 

 ticularly the Aroa abundant in copper, seem to call for tlie 

 industry of the miners. 



Argillaceous schist is very scarce : it covers the micace- 

 ous schist on the southern declivity of Venezuela, in the 

 neighbourhood of the Llanos, in the Quebradas deMalparo, 

 and Piedra Azul : there is blue argdlaceous schist, with 

 veins of quartz, on the isthmus of Cariaco, near Chupa- 

 ruparu, in the Distillador Arroyo du Robola, and also on 

 Macanao. In the four last-mentioned places there are 

 found in the argillaceous schist alum and vitriolic schist, in 

 strata of two or three feet in thickness, which effloresce 

 sulphate of alumine, or natural alum, with which the Indi- 

 ans of Guayqueries carry on a little trade. 



Serpentine is found on the cordillera of Venezuela above 

 micaceous schist, on the surface of Villa de Cura, at the 

 height of t?}5 toises ; between the Cerro de Piedras Ne^ras 

 and the Rio Tucutuncmo, here and there green olivin mixed 

 withgliunner, without garnets, schillerspath, or hornblcnd, 

 but with veins of bluish lardstonc. 



Grunstein (green rock), original trapp, an intimate union 

 of hornblend and feldspar, sometimes mtcrmixed with sul- 

 phureous pyrites and quartz, often confounded with ba- 

 saltes, and very little known in Europe, is found in strata 

 of two fathoms in tliickness, or balls of from three to four 

 feet in diameter, composed of concentric strata united with 

 micaceous schist or original argillaceous schist, in several 

 places of the northern and southern declivity of the cordil- 

 lera of the mountain Avila, in the sea near Cape Blanc, in 

 a real vein which traverses the strata of gneiss, but inter- 

 mixed with newer granite, which tills up the vein between 

 Antimano and Carapa near Caracas. The gray stone con- 

 tains liere red garnets which I have never seen in Europe- 

 I have sent specimens of them to Madrid in the first box 

 which I transmitted to the captain-general of Caracas. 



II. Kind of Mountains which form flie Transition froirh 

 lYunitivc to Alluviul Mountains. Formation of the 

 Trunsilion of IVcrner. 



This formation is found in particular to tlie north of the 

 Parirna cordillera, opposite to Caccara, and in large masses 

 on the southern declivity of the Venezuela cordillera. Be- 

 tween the llanos and JVIorros of S. Juan, between the \'ill.i 

 de Gura and l^arapara, between longitude 9" 33' and 9" 55', 

 one seems to enter a land of basaltes, on descending from 



the 



