132 PATAGONIAN EXPEDITIONS! NARRATIVE. 



ments, when attempting to fix the boundary limits between the two coun- 

 tries. 



Our camp on this small stream lay just in front of a lofty and precipitous 

 bluff of hard, coarse standstones, which formed the southern border of the 

 western half of Mayer Basin. We were now on the very edge of the 

 dense forests that everywhere clothe the lower slopes of the southern 

 Andes. To the south and southeast were considerable exposures of sedi- 

 mentary rocks, that as yet remained to be examined. The bluff which 

 formed the southern border of Mayer Basin, directly south of camp, had 

 an elevation of perhaps three thousand feet above the stream and its 

 summit afforded an exceptionally fine view of the surrounding country. 

 On the morning following our arrival at this camp, I climbed to the 

 top, examining the different strata as I passed over them. The coarser 

 sandstones at the bottom were quite barren of fossils and seemed very 

 similar to those we had previously seen near the source of the River 

 Chalia, or Sheuen. Here, however, they were overlaid by several hun- 

 dred feet of variegated clays, alternating with an occasional thin stratum of 

 sandstone. At several localities in the clays I found fragments of the 

 bones of dinosaurs, and occasionally a nearly complete vertebra, or foot- 

 bone. In a pinkish colored stratum near the summit -I came upon a 

 nearly complete fore limb of a large dinosaur. The weight of the hume- 

 rus alone could hardly have been less than two hundred pounds. I 

 wished very much to take this limb, but its great size and weight would 

 have precluded our taking it with us to the coast, hence I left it where it 

 was, hoping that I might again return to the same locality on some later 

 expedition, better equipped with means of transportation. 



The face of the cliff was perfectly bare of vegetation, and where the 

 clays predominated, the slopes were exceedingly slippery from being thor- 

 oughly saturated with moisture by the recent rains. This rendered their 

 ascent exceedingly difficult and not wholly without danger. I fear my 

 poor horse had arrived at the conclusion, long before we reached the sum- 

 mit, that he had fallen into the hands of a hard master. What rendered 

 the travelling even more difficult was the presence of great numbers of 

 mud-streams encountered at the bottoms of the smaller gulches, with which 

 the face of the bluff was furrowed. Usually these were only small affairs 

 and could be easily crossed, but in not a few cases they were of no incon- 

 siderable dimensions, being several rods in breadth and of unknown 



