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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- 
coaching 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 readjly 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. RN : 
Having reached the further side of the plain, and crossed 
2 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 half a league across, and nearly 
-> Cerro, Hill This name is given to the town situated among the hills, to 
distinguish it from the old town of Pasco, (Pasco viejo,) which stands at the 
edge of the plain, two leagues to the southward. _ 
02 
