CHAPTER VII. 



Through the lava fields; Lavas not of submarine origin; Rio C Italia or 

 Sheuen; Bad lands in Santa Cruz formation ; The finding of a human 

 skeleton; In tlie valley of Rio Chalia; Mosquitoes; The Armadillo; 

 Sierra Ventana; The Rio Chico and its basalt-capped canon; Cyanotis 

 rubrigaster; The Patagonian mocking bird ; Burrowing owls ; Owls and 

 rodents; Protective coloration in sand lizards; Character of river caflon 

 and basaltic platforms ; Barren nature of t lie lava beds; Our first view 

 of the Andes from the valley of the Rio Chico; A terminal moraine;. 

 Abundance of rodents; Cavia australis; Ctenomys magellanica, tlte 

 Tuco-tuco; Numerous mice ; Terrific rainstorm ; Destruction to animal 

 life wrought by storm ; Effects of burrowing animals on erosion ; Ascend 

 south fork of t lie Rio Chico; Glacial moraines and lakes along the upper 

 stretches of tlie river; Enter Mayer Basin by way of Shell Gap; On 

 the outskirts of the Andean forests. 



THE country to the north of the river at this point had the appear- 

 ance of being much more broken and obstructed by lava beds 

 than that to the south. So that we anticipated some difficulty in 

 getting up out of the river valley upon the pampa. Before starting, on the 

 morning of the fourteenth I rode out on horseback to inspect the bluff and 

 find, if possible, a practical route out of our present situation. I was not 

 long in discovering such, and soon returned to camp, when we immedi- 

 ately set out on our journey northward. We had soon crossed the barren, 

 shingle-covered valley of the river and were ascending the steep, rugged, 

 lava-covered slope to the north. By winding in and out among the pro- 

 jecting ledges and taking advantage of every incline that offered a promis- 

 ing trail to the summit of the next higher platform, we gained the top of 

 a low table which lay between the river valley and a narrow, deep basaltic 

 canon, which entered the latter a little way below. Keeping along on the 

 surface of this table for a distance, we came to a point where the bottom 

 of the cafton opened out into a broad open stretch of meadow-land, per- 



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