18G8.] ARGYLL ARGYLLSHIRE. 261 



" followed along the same line by the larger faults, and by the anti- 

 clinal and synclinal axes." Geological structure, then, we have it 

 admitted, has determined the direction and the general parallelism 

 of all the longitudinal valleys of the Highlands, which may be roughly 

 stated at about one-half of the whole. It is true that nothing but 

 the general trend and direction of these valleys seems to be attri- 

 buted to geological structure. Strata of different degrees of hard- 

 ness are supposed to have been exposed along the line of strike to 

 the agencies of waste. These would cut away the softer strata more 

 rapidly than the harder, and, being once determined in a particular 

 direction, have gradually widened their channels, at first mere narrow 

 cuttings, into deep glens and valleys. But again it is further admitted 

 that the great faults of the country lie along the same line, as like- 

 wise the synclinal and anticlinal axes. These of course are due, and 

 due solely, to subterranean movements ; and so far as they are 

 coincident with the ridges and hollows of the longitudinal system, 

 they establish the lasting effects of such movements upon the existing 

 surface of the country. 



How far, then, can this coincidence be traced ? Here I regret to 

 say I must part company with Mr. Geikie even in his account of 

 facts. He says broadly, in the first chapter of his work, that " For 

 one valley which runs along the line of a dislocation there are, I 

 dare say, fifty or a hundred which do not." And in a note on .the 

 same page he adds emphatically that there is no point which the 

 detailed investigations of the Geological Survey have made clearer 

 than this. I feel aU the boldness of contradicting one who is not 

 only an eminent geologist, but who has so long been specially engaged 

 as a geological surveyor. But as regards the vaUey-system of the 

 county of Argyll, I do venture to state my conviction that this 

 assertion is erroneous. And I am glad to observe that in a subse- 

 quent page of his work Mr. Geikie says that, '^ until the Highland 

 tracts are surveyed in minute detail, it will not be possible to ascer- 

 tain how far they are traversed by lines of fault, nor to what extent 

 such features have shown themselves at the surface and have served 

 to guide the excavation of the valleys." 



As regards the Lowlands over which the survey has been carried, 

 the result seems to have effected some modification of the confidence 

 with which the Erosion Theory is asserted. Our author says, " after 

 a long and detailed examination of the contorted rocks of the Silurian 

 uplands of the Southern counties, I have been led to believe that the 

 faults and folds of the strata have on the ivhole only a secondary 

 influence in originating the present irregularities of the surface. 

 And this is probably the case also with the contorted and metamor- 

 phosed Silurian rocks of the Highlands." So far as this passage 

 involves an argument, it does not seem a very good one. The 

 Highlands, as compared with the Lowlands, are what their descriptive 

 name implies them to be. 1 hey are lines of special upheaval and 

 subsidence and contortion ; and it is not probable, but in the highest 

 degree improbable, that an area of country under which subterranean 

 movements have been so much more marked than elsewhere should 



