I 1 8 PATAGONIAN EXPEDITIONS : NARRATIVE. 



just beneath the crater. Resting upon this columnar mass of basalt 

 are some two hundred feet of heterogeneous igneous materials consisting 

 of great masses or lenses of obsidian and heavier slags near the base, 

 and passing into highly vesicular pumice and scoriae toward the summit, 

 the whole exhibiting a striking variety of most brilliant colors, jet black, 

 steel blue, vermilion and ochre predominating. From the summit we 

 obtained an excellent view of the surrounding country. To the south in 

 the foreground lay the low, level pampa which separates the Rio Chico 

 from its smaller tributary the Rio Chalia, while beyond the latter stream 

 rose the high pampa over which we had travelled on our way north from 

 the Santa Cruz River. To the north and west of us, and extending along the 

 north side of the river far to the east, were lofty and rugged basalt-capped 

 table-lands. Of the exact nature and extent of these we had at that time 

 no adequate conception. The valley of the river stretched away to the 

 east, bounded on the south by a low, grass-covered plain and on the north 

 by the basalt-covered table just mentioned, which rose to a height of four- 

 teen hundred feet. To the west the river could be seen emerging, at a 

 distance of about ten miles, from a deep canon with walls on either side 

 capped by lofty, precipitous basaltic platforms, towering fourteen to fifteen 

 hundred feet above the stream. Within a radius of a few miles from where 

 we sat there were no less than a half dozen old volcanoes all similar to, and 

 equalling in beauty and interest, the one we had climbed. As I sat and 

 surveyed the surrounding scene from my point of vantage, I was deeply 

 interested in all the various phenomena about me. Each showed on what 

 an enormous scale nature engages in her work both of construction and 

 destruction. I could not resist the temptation to reconstruct in my mind 

 the appearance of the surrounding country during the different epochs 

 through which it had passed in arriving at its present, to say the least, 

 half desolate condition. How different from the present were the condi- 

 tions when, during the process of the last elevation of this region above 

 the sea, the low plain which now lay to the south was still submerged 

 beneath a great bay from the Atlantic, in the midst of which the pin- 

 nacle upon which I sat was a small, rocky, wave-swept islet. Then 

 again, how different from either was that other, and as it appeared to 

 me, more remote period, when the volcano on the lip of whose crater I 

 now sat in security, together with the others in the surrounding neigh- 

 borhood, were in a state of violent activity and the great masses of 



