506 GENERAL COMPARISON OF 



identity in the distribution of the hills and valleys, which 

 seem equally in both cases to have determined the posi- 

 tions of those lines. The forms, indeed, of these sea lochs, 

 and their intimate connexion with that aestuary, together 

 with the obvious general causes which have determined 

 the former, and the analogous ridges which bound the 

 latter, point to one common origin for all these inlets ; 

 namely, that general cause which determined the form 

 and direction of the islands and of the continent of 

 Scotland. 



It has however been shown, in describing the sandstone 

 deposit of these islands, that it bore the marks of waste in 

 a great degree ; indications of which are found, not only in 

 the partial occurrence of this rock in Cantyre, but in the 

 cliffs of Arran and in the trap veins visible in the several 

 islands ; the persistence of which remain as records of the 

 loss of the surrounding strata. There is therefore abun- 

 dant proof that the original extent of these islands was 

 more considerable, and their intimacy of position greater 

 than it is at present ; but whether we are justified in 

 concluding that they ever were continuous, is a question on 

 which it is hopeless to speculate. 



I must here remark that no traces of the red sandstone 

 are found within Loch Fyne ; the northern limit of that 

 rock being situated considerably to the south of its junction 

 with the Clyde. If therefore the sandstone of Cantyre, 

 Arran, Bute, and the mainland, were judged to have been 

 once continuous, that extensive inlet must have been a fresh 

 water lake discharging its waters through a channel between 

 Bute and Arran, or between the latter island and Cantyre. 

 But such discussions add nothing to the stock of our infor- 

 mation. It must also be recollected, as already suggested, 

 that as the sandstone has been shown to possess an undu- 

 lating disposition, it is equally possible that the original 

 distribution of that deposit has, like those of the ridges of 

 primary mountains, been the cause of the present general 

 form of the estuary in this part of the Clyde, and of the 



