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that the valley in which it stands passed through an extensive 

 formation of Trachyte. A small stream runs in the bottom, 

 from which a steep grassy slope rises on each side, surmounted 

 by a craggy and precipitous wall of the Trachyte rocks. 

 Half a league below the town, we passed some hot springs : 

 the water leaves a calcareous deposit, which is gradually en- 

 croaching upon one side of the valley. 



At the lower extremity of the valley, the Trachyte is divided 

 into columns, coated with blackish Lichen, that from a distance 

 gives them the appearance of Basalt, The masses have 

 been very differently acted upon by the weather, some parts 

 disintegrating more readily than others. Many columns 

 stand alone ; they are obliquely divided by transverse fissures, 

 and the different joints have been unequally worn, so that a 

 slender shaft sometimes supports an immense mass on its 

 summit, and the whole has the appearance of architectural 

 ruins, interspersed with grotesque colossal figures. 



On emerging from the valley, we found ourselves at last 

 on the plains of Bourbon, which extend fifteen or twenty 

 leagues from north to south, presenting a surface of green 

 sward as level as a bowling-green. We had now only to 

 travel six leagues to the mines, situated among the hills on 

 the opposite side of the plain. At the distance of two leagues, 

 we passed a low belt of limestone, and we crossed three small 

 rivers on our way. When we looked at the vast meadow 

 over which we were travelling, bounded by gently swelling 

 hills that shut out the view of the distant snowy peaks, we 

 could hardly persuade ourselves that we were fourteen 

 thousand feet above the level of the sea. 



Having reached the further side of the plain, and crossed 

 a range of limestone rocks, we came abruptly upon the 

 town and mines of the Cerro de Pasco,* which occupy one 

 side of an open space, about lialf a league across, and nearly 



* Cerro, Hill. This name is given to the town situated among the bills, to 

 distinguish it from the old town of Pasco, {Pasco viejo,) which stands at the 

 edge of the plain, two leagues to the southward. 



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