1868.] ARGYLL ARGYLLSHIRE. 271 



strata, which strike has been determined by the geological and sub- 

 terranean force which tossed the strata-like waves from north-west 

 to south-east. 



As regards, again, the argument derived from one general average 

 height, I must remark, in the first place, that the irregularities of 

 height are very great — that BenCruachan, for example, towers high, 

 head and shoulders above all the lower hills to the south and west, 

 that Ben More stands in the same relative position to the hills of 

 Mull, and so on. Of course there is a maximum height in every 

 mountain-country ; and of course also a large number of the higher 

 hills make a more or less near approach to this maximum elevation. 

 But I entirely deny that it follows from this, or that any presump- 

 tion whatever arises from this, that the whole country was once one 

 gTeat hog's-back or tableland at or near the level of what are now 

 a few solitary peaks, and that all the rest of the country has simply 

 been blocked out and cut away by the agencies of erosion. Nothing 

 can be more certain than that from any given mechanical subter- 

 ranean force, acting on rocks of a given hardness over a given area, 

 a certain amount (and a very large amount) of uniformity would be 

 produced in the height and depth as well as in the direction of their 

 imdulations. If a powerful wave were to pass under ice so as to 

 break it up along certain lines of upheaval and depression, and if 

 the breaking pieces could be retained by some viscid matter in the 

 forms they would take in breaking, I apprehend that there would 

 be found a general average in the height to which they would 

 rise, and in the depth to which they would sink in the act of giving 

 way. In like manner, if along several miles of country occupied by 

 a hardened crystalline rock, like mica- slate, there came an earth- 

 quake wave so powerful as to toss it like waves of the sea, it would 

 break along certain lines, and the height to which it would rise in 

 one place and sink in another would bear a definite proportion to 

 the amount of force and to the power of its own various beds to 

 bear difi'erent degrees of tension. I see nothing whatever, therefore, 

 either in the average height of the Highland hills, or in the sym- 

 metry of the valleys, to compel me to adopt the extreme opinion ad- 

 vocated by Mr. Geikie. 



I cannot conclude this paper without observing on the assumption 

 made by him that his own theory has the exclusive merit of resting 

 upon the " known and visible causes of change," whilst all who difi'er 

 from him have to imagine the former existence of other causes far 

 more stupendous '' merely " because the results achieved seem other- 

 wise " inexi^licable." My complaint of Mr. Geikie's theory is precisely 

 this — that it is not based upon the known and visible causes of change 

 "as these are revealed by their known and visible effects." Por, of 

 course, it is in this sense alone that we can speak of either class of 

 agency as now " visible " in the Highlands. True it is that we do not 

 now see them moved by subterranean force. But neither do we now see 

 them sculptured by enormous glaciers. The frosts of Greenland are 

 a visible cause of change ; but so arc the fires of Hecla. Neither of 

 them now affect the area of the Highlands. But Mr. Geikie con- 



