196 PATAGONIAN EXPEDITIONS : NARRATIVE. 



was no reason why I should not be spared the irksome duties of a team- 

 ster and devote my entire time as we passed along to a study of the sur- 

 rounding country. Taking advantage of this opportunity, I carefully 

 examined the materials constituting the bluffs of the Rio Chico, deter- 

 mined the altitude of the basaltic platform and the upper limits of the 

 shingle at many different localities, beside making many other observa- 

 tions relating to the geology and geography of the region, which will be 

 of especial interest when I come to discuss the geologic and geographic 

 history of this district. 



Our purpose in again visiting the country about Lake Pueyrredon was 

 to explore the region more thoroughly than I had been able to do during 

 my first visit, in the hope that we might find somewhere in that vicinity 

 exposures of the Pyrotherium beds, which, from the publications of Dr. 

 Florentino Ameghino, I had been led to believe might be quite possi- 

 ble. We spent several days on the summit of the mountain lying south 

 of the lake in the midst of frequent and blinding snow storms and with 

 altogether most inclement weather. Although failing in our principal 

 purpose, we secured a considerable collection of vertebrates and inverte- 

 brates from the Santa Cruzian, Cape Fairweather and Patagonian beds. 

 I was also successful in discovering a number of new and highly fossilif- 

 erous horizons in the Cretaceous at the mouth of the canon of the Rio 

 Tarde, and at a second locality near White Lake, some ten miles farther 

 east. From these I secured some thirty-six new species of invertebrates, 

 according to the determinations of Dr. Stanton, in whose hands they were 

 placed for examination and description. The results of Dr. Stanton's 

 investigations form Part I. of Vol. IV. of the Reports of the Expeditions. 



After some two weeks spent in the vicinity of Lake Pueyrredon, we 

 decided to return to the coast. Messrs. Peterson and Brown, with the 

 wagon and outfit, returned by the route by which we had come, while I 

 parted company with them a short distance east of Lake Pueyrredon, and 

 with pack-mule and saddle-horse started off to the south to explore the coun- 

 try lying between the lake and the headwaters of the Rios Belgrano and 

 Chico. On the day previous to our separating, while ascending one of the 

 lower benches of the bluff that rises above the valley extending east of the 

 lake, I observed a mountain lion that had been frightened from its place of 

 concealment and went galloping up the bluff and across the narrow plain at 

 the top. As the country was an open one and I was mounted on a good 



