TI 4 
BAHIA BLANCA TO BUENOS AYRES 
CHAP. 
up to a height of between 800 and 900 feet above the sea. 
In the morning (9th of September) the guide told me to ascend 
the nearest ridge, which he thought would lead me to the four 
peaks that crown the summit. The climbing up such rough 
rocks was very fatiguing; the sides were so indented, that 
what was gained in one five minutes was often lost in the 
next. At last, when I reached the ridge, my disappointment 
was extreme in finding a precipitous valley as deep as the plain, 
which cut the chain traversely in two, and separated me from 
the four points. This valley is very narrow, but flat-bottomed, 
and it forms a fine horse-pass for the Indians, as it connects 
the plains on the northern and southern sides of the range. 
Having descended, and while crossing it, I saw two horses 
grazing: I immediately hid myself in the long grass, and 
began to reconnoitre ; but as I could see no signs of Indians I 
proceeded cautiously on my second ascent. It was late in the 
day, and this part of the mountain, like the other, was steep 
and rugged. I was on the top of the second peak by two 
o’clock, but got there with extreme difficulty ; every twenty 
yards I had the cramp in the upper part of both thighs, so 
that I was afraid I should not have been able to have got 
down again. It was also necessary to return by another road, 
as it was out of the question to pass over the saddle-back. I 
was therefore obliged to give up the two higher peaks. Their 
altitude was but little greater, and every purpose of geology 
had been answered ; so that the attempt was not worth the 
hazard of any further exertion. I presume the cause of the 
cramp was the great change in the kind of muscular action, 
from that of hard riding to that of still harder climbing. It is 
a lesson worth remembering, as in some cases it might cause 
much difficulty. 
I have already said the mountain is composed of white 
quartz rock, and with it a little glossy clay-slate is associated. 
At the height of a few hundred feet above the plain, patches 
of conglomerate adhered in several places to the solid rock. 
They resembled in hardness, and in the nature of the cement, 
the masses which may be seen daily forming on some coasts. 
I do not doubt these pebbles were in a similar manner 
aggregated, at a period when the great calcareous formation 
was depositing beneath the surrounding sea. We may believe 
