Ancient Moraines in Argylesliire. 197 



tain pass. As any of these uses is quite irreconcileable with 

 the position they occupy, the excursionists from Kilmun and 

 Dunoon, who pass them on their way to the waterfall a mile far- 

 ther up the valley, must have been sorely perplexed to account 

 for their origin. Their great size demonstrates that they must 

 owe their birth to some powerful agent. The elevation of the 

 larger one, B, above the bank of the stream on its south side, 

 as measured by a pocket level, I found to be 77 feet. The ele- 

 vation of A, above the hollow which divides it from B is 40 feet. 

 (See Section 1, below the map, which gives the profile along 

 the line a, b; r is the river.) The length of B across the 

 valley, in the direction h, g (see Section 4), is 320 feet; 

 but it is truncated at the east end by the passage r, which the 

 river has cut, and its original length must have been 350 feet, 

 which is the present length of A. Both mounds are covered 

 with herbage, but the truncated end of B discloses the nature 

 of their materials, which is seen to be a confused assemblage of 

 gravel and sand, with a few blocks of the mica-slate intermixed. 

 Admit that they are ancient moraines, and every difficulty 

 connected with their existence here disappears ; and we shall 

 seek in vain for any other rational explanation of their origin. 

 Moreover, other evidence of the presence of mighty masses of 

 ice abounds in the valley. Marks of abrasion may be seen on 

 the contorted laminae of the mica-slate to the height of some 

 hundred feet ; projecting ledges of the rock have their north- 

 ern faces smoothed, while the southern remain rough, showing 

 the direction in which the ice moved ; and a highly inclined 

 or nearly vertical surface, 10 feet high, just opposite the trun- 

 cated end of B, and within 30 feet of it (under h in the map), 

 is beautifully marked with horizontal grooves, from half an 

 inch to an inch in breadth. There are other fine specimens 

 of striation and grooving on the rock at a greater height, and 

 the perfect condition in which these traces of glacial action 

 are preserved is readily explained by the planes of stratifica- 

 tion being at right angles to the line of the valley, so that the 

 gliding mass of ice would pass right across the edges of the 

 strata. It is always under such circumstances that the striae 

 and groovings are most distinct. When a glacier moves along 

 the planes of a schistose rock, it will smooth the exposed surface 



