NOTES ON THE ARGENTINE REPUBLIC. 
9 
employers, thus showing their trustworthiness when placed in 
positions of responsibility, 
In the future there can be no doubt the province of San 
J uan will be an important contributor of metals ; the principal 
known mining centres are Tontal, Gualilan, Hilario, La Huerta, 
Castania, Gruachi, Chila, and Salado. 
Gualilan, one of these, is situate in a district full of geo- 
logical interest. The road to it strikes a little to the north-west 
of the town of San Juan, across the river of that name. This 
river, made up of the Bio de los Patos and the Bio del 
Castania, the latter coming through a district in which gneiss, 
schists, granite, and sandstone abound, furnishes the greater part 
of the micaceous matter so abundant in the waters of the San 
Juan. On the northern side of the river, here running nearly 
due east, is a range of hills, the Sierra de Yillagun, composed 
of limestones and sandstones, with a direction nearly due north 
and south, and a dip of from 40° to 45° west. 
On the eastern side of this range ironstones and bituminous 
shales are found, and of a northern continuation we shall have 
occasion to speak subsequently. Imperfect specimens of 
Ammonites communis and A. Bucklandi have been found here, 
and there can be little doubt that we have here the Liassic 
group of the Jurassic system. 
This range of hills, 2500 feet above the river, or 4500 
feet above the sea, increases in height, like the limestone 
ranges west of it, towards the north, and reaches a height 
of 18,000 feet. 
Going again to the north-west, the road crosses a desert 
about twenty-five or thirty miles to Talacastro, where it goes 
through a pass in the Sierra de Jachal. Here we meet with a 
limestone somewhat darker in colour, the formation much the 
same generally, ‘but the layers of limestone thinner, and dip- 
ping west at an angle of 65° in the highest hills, about 1500 
feet above the road. The contortions of the strata at the 
entrance of the pass are very remarkable, but further up the 
stratification becomes regular and distinct, until we reach 
some irregular shaly and sandstone beds, in the former of 
which are found ‘ gossans ’ and quartz containing gold and 
silver, to the amount of 1 J oz. of the former to 2 or 3 oz. of 
the latter. 
From the summit of this pass in the ‘ Camina de Borros,’ 
(donkey road), the direction of the range of hills in which the 
Gualilan mining region lies, can be traced away north into the 
Sierra de Jachal, which rises from a height of 7000 to 16,000 
feet above the sea, in a distance of about forty miles. The view 
from the highest point of this road is extremely beautiful ; a 
sandy desert with a scrub growth around it, and one or two 
