l8o PAT AGONIAN EXPEDITIONS : NARRATIVE. 



then enters the main basalt cafion mentioned above as continuing below 

 the lake formed by the last terminal moraine crossing the valley which 

 extends east of Lake Pueyrredon. The bottom of this canon is likewise 

 destitute of any running water, but is remarkably picturesque. It extends 

 in an easterly direction for a distance of some three or four miles, where it 

 enters the principal one of that intricate series of cafions, by which the 

 surface of this country is dissected. This cafion, unlike the others we have 

 been noticing, is traversed by a considerable stream of beautiful, clear 

 water well stocked with fish. Its walls rise to a height of over 2,000 feet 

 and the rocks composing them are made up of a rather complicated series 

 of igneous and sedimentary materials, the age and nature of which, for the 

 most part, I was quite unable to determine. Figs. 7, 9, 10, 22, 25-28, 30 

 and 38 are scenes from this interesting region. 



The point where the two cafions meet (Fig. 30) had in times past been 

 a favorite Indian camping ground, as was plainly evidenced by the pres- 

 ence in great numbers of fragments of broken pottery, stone arrow-heads 

 and other implements, as well as the broken and charred bones of fishes, 

 birds and mammals. 



During the first week of our stay at this camp I searched faithfully 

 the surrounding country, within riding distance, for evidences of the Pyro- 

 therium beds and fauna, but without any success whatever. Then, taking 

 with me an extra pack-horse, I explored the country to the eastward for 

 fifty to seventy-five miles and northward as far as the eastern end of 

 Lake Buenos Aires, likewise without success in so far as my work related 

 to the discovery of the Pyrotherium beds and fauna. In other respects, 

 however, I was quite successful and secured considerable information 

 relative to the geology and geography of the surrounding region, as well 

 as important palaeontological materials. While thus engaged, it was my 

 custom to take with me on each of my excursions, in addition to my 

 saddle-horse, a pack-horse with tarpaulin, extra pair of blankets, and pro- 

 visions sufficient for a couple of weeks, consisting of bread, rice, split 

 peas, a small bag of pepper and salt mixed, tea, coffee and sugar. For 

 meat I depended on my revolver and the game birds and mammals of 

 the country through which I was travelling, and my supply was seldom, 

 if ever, deficient. 



During my first excursion I passed some ten days in exploring the 

 country to the eastward. I first followed down the main cafion for per- 



