Sketch of the Mime of Pasco. 55 
Upon the gres, rests the white Alpine limestone, (so called from 
being the same in form with that of the Alps,) as in the acclivity of 
Uliachin, Yanamente, chain and pampas of St. Juan, shores of 
Quinlacocha, Colquyurca, Vinchos and Pargas. The conglomerate is 
well distinguished, as in the rocks of Suco, and Chaquilguanca, where 
it makes a grand fortification, of more than three hundred yards high. 
The calcareous formation is the most extensive, since it may be said 
to be the most common matrix of metals of silver in this place ; all 
to the east of Yauricocha, the contiguous rough grounds and hills of 
the plain of Bourbon, are composed of this rock, which forms hori- 
zontal strata, inclining to the east, and in some parts, as in the bro- 
ken land of Quinlacocha, and shores of the River Ranca, it is fre- 
quently observed in the zigzag form; and in the broken land of 
Uliachin and St. Juan, the strata appear perpendicular, from the ex- 
cavation which the taza of Yauricocha forms. This limestone is blue, 
and semi-compact, and contains veins of calcareous white spar ; the 
shells are scarce, and in it are some metallic strata, principally lead, 
and sulphureous pyrites, which produce silver. In the hill of Vin- 
chos, this formation is more extensive, and lies more distinct, as is 
seen in the road from Pasco to this point, and principally in the height 
of Chaguanaco, and rocks contiguous to Chaquilguanca; but de- 
scending to the deep uneven ground of Janio, the gres insensibly dis- 
appears, and passes to an argillaceous esquito. Vinchos is rather 
valuable, owing to its strata being composed of lead and pyritous 
minerals; it has three peaks which are called Maman Vinchos, Gua- 
quan Vinchos, and Riuam Vinchos. All three are composed of 
blue limestone, half decomposed on the surface; presenting inequal- 
ities and roughness, which prevent the traveller from ascending to its 
summit; the calcareous strata are almost horizontal, and those of 
the lead veins have the same direction; and are in the mine from a 
half a yard, to a yard wide. In that of Descubudora, which is the 
most celebrated, the stratum is about twelve inches broad, and one is 
composed of pyrites, which are ferruginous and very compact; this 
prevents the mine from being worked to advantage ; almost all this 
ledge is traversed by metallic strata, the minerals of which, yield at 
least from eight to thirty marks the cajon; but there is a great in- 
convenience arising from the want of instruments and combustibles, 
for the foundery. On the north, the soil continues forming slopes, 
and contains many strata of pacos in the gres, extending almost as 
far as the village of Mosca, in the neighborhood of which, are found 
