Fenton — Physiography and Glacial Geology of S. Patagonia. 223 



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the fringe of the moraine, can be seen in places at no great distance, not more 



than tliirty or forty feet, below the sui'face of the 

 shingle ; consequently the surface of the tertiary 

 rock also falls in level as we proceed towards the 

 west, and this fall begins after it becomes overlain 

 by the moraine proper. The accompanying diagram 

 will explain these facts more clearly. Unfortu- 

 nately, I have never had an opportunity of going 

 further west than the middle of the Douglas land, 

 so I could not study the further topography of this 

 plain in detail ; however, from the tops of several 

 high hills I could see in the distance about twenty 

 miles further west than Douglas Estaneia another 

 line of high ground as if a second line of terminal 

 moraine similar to that which I have been describing. 

 Intelligent people from whom I have made inquiries 

 have informed me that practically the same sequence 

 of change is found here, namely, a sudden rise of level 

 and a gradual fall, which finally reaches the sea-level 

 at the channels. I have always found that the ter- 

 tiary rock, even in the middle of the volcanic area, 

 follows a very even course and exhibits very little 

 tendency to dip in any direction, so that I can only 

 conclude that this sloping down to the west is here 

 due to erosion, and that this erosion was of glacier 

 origin. The peculiar sloping erosion of the tertiary 

 rock coincides exactly in extent with the moraine, 

 and we cannot help coming to the conclusion that 

 the same agent operated as a cause in both instances. 

 Once we get well inside the moraine area, we notice 

 that terracing practically disappears from the river 

 valleys. A. little below the Bella Vista settlement, 

 at the mouth of the Gallegos Chico, where it joins the 

 Gallegos river, the lower terrace has been cut down 

 by the former river (Gallegos Chico) to the level of 

 the present river valley. This cutting would seem 

 to have belonged to the last erosive phase of the 

 river-valley cutting process, and must have been 

 subsequent to the formation of the moraine-covered 

 terrace further along. Yet down in the mouth of 



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