MEETING WITH THE CHILIAN BOUNDARY COMMISSION. 171 



and described by Darwin. The rocks in reality form a considerable 

 dome-like, mountainous hogback, which, with an altitude of perhaps fifteen 

 hundred feet, is continued out into the middle of the valley at right angles 

 to the general trend of the main range, Its surface is deeply scored and 

 polished and these features, together with the glacial materials left 

 stranded at an altitude of fully three thousand feet above the bed on 

 either side of the main valley, bear unmistakable evidence that at some 

 previous period the ice of a mighty glacier filled this great depression and 

 overflowed on the surrounding hills, extending eastward over the plains 

 for a distance of fully sixty miles, as I afterwards discovered by tracing 

 the terminal moraine. The enormous erosion and deposition accom- 

 plished by this mass of ice is partially indicated by the several hundred 

 feet of glacial material shown in the walls of the canon of the Rio Blanco. 

 These glacial materials I subsequently observed to extend eastward to a 

 distance of from forty to fifty miles. 



The very nature of the materials constituting the rocks of this mountain 

 precluded the possibility of my finding fossils, but the remainder of the 

 day was well spent in an examination of their lithological nature and in 

 learning what I could of the geography of the region. Late in the 

 evening I returned to my horse, where, in the shelter of a clump of bushes, 

 I retired for the night. 



The following morning, after an early and hastily prepared breakfast, I 

 continued my journey, directing my course toward the southeastern ex- 

 tremity of Lake Pueyrredon. Hardly had I started, when, from a shallow 

 depression in the surface of the valley in front of me, there appeared a 

 small column of smoke rising into the atmosphere. This was interesting, 

 for since leaving the settlements near the mouth of the Rio Chico, we had 

 seen no one. Continuing in the direction from which the smoke was 

 seen to rise, I soon came in sight of three men and a number of horses. 

 On conversation with the men I found them to belong to the Chilian 

 Boundary Commission, engaged in a preliminary survey, with a view to 

 determining the boundary line between Chilian and Argentine Patagonia. 

 From the first it was quite evident that there was mutual surprise at our 

 meeting in such an unexpected time and place. After a few moments 

 spent in conversation with these men, the only persons beside my com- 

 panion that I saw during this my second trip into the interior, I bade them 

 good-bye and continued my journey toward Lake Pueyrredon. 



