222 Scientific Proceedings, Royal Dublin Society. 



luidulatory pampas can, ou careful observation, be distinctly seen : the 

 difference in level does not at first seem to be more than fifty feet or so, 

 perhaps even less ; yet the topography of the two plains is distinct. So far 

 I have not seen an erratic, but hope to see one soon." I restarted along the 

 track, and my next note is as follows : " Had not gone three hundred yards 

 beyond the point where I wrote the above when I came on erratics ; not 

 one but several, showing their tops here and there above the ground, several 

 feet in diameter. A little further along they can be seen in all directions ; 

 are non-voleanie, and many of them are very large." For about two leagues 

 at least the surface ha,d a tendency to slightly rise, and the rather spread- 

 out drumlin appearance was well marked. About three leagues from the edge 

 of this great moraine is a deep canadon, running more or less north-west and 

 south-east, with a floor so level that it was very difficult to say which was 

 the direction of its outflow. Its inclination proved to be backwards, away 

 from the valley of the Gallegos. In fact, this canadon ran into a series of 

 bajos, which eventually, further to the west, discharged themselves into the 

 Gallegos river through a series of caiiadones. 



Douglas Estancia is situated in a canadon about thirty feet below the main 

 pampa, about twenty miles to the west of the edge of the terminal moraine. 

 On one or two occasions I carefully estimated its height above the river as 

 about two hundred feet. All the pampas round about the Douglas settlement 

 exhibit a well-marked glacial topography, showing drumlius and erratic 

 blocks everywhere, and consequently these differences in level seemed peculiar. 

 The river runs a very even course from the Douglas camp to the point opposite 

 the end of the terminal moraine below Bella Vista; there are practically no 

 rapids, and the difference in levels in the two localities cannot consequently 

 be more than fifty feet, if so much. This wiU leave the end of the great 

 moraine about two hundred and eighty feet higher than the plain at Douglas, 

 which is undoubtedly a continuation of the same glacial feature. The particular 

 glaciation which we are now dealing with thus left behind it a large and 

 •extensive moraine, at its eastern termination two hundred and eighty feet 

 higher than its level twenty miles further to the west. The topography of this 

 area is rather complicated by the presence of a long narrow ridge which 

 •extends out into it from the cordillera in the west ; it is about six hundred 

 and fifty feet above the plain at Douglas Estancia, and the ridge is covered 

 by moraine material and shows well-marked drumlins and erratics. It is on an 

 average about a mile or two in breadth, and the fall on the north side is much 

 less than that on the south. I did not estimate its height above the northern 

 plain, but I should judge it to be about one hundred and fifty feet. Now, the 

 tertiary rock underlying the outwash gravel on the flat plain, even close to 



