114 BAHJA 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 



