THE CLYDE ISLANDS. 505 



is included within the red sandstone, and, that in Bute, 

 it lies between two masses of trap. Although the effects 

 of the trap of Bute may be judged sufficient to have 

 perverted the natural order of a portion of the regular 

 coal strata, thus causing the present appearances, the same 

 cause seems inapplicable to the case of Arran ; unless it 

 be also imagined that the upper red sandstone of this 

 island is actually a portion of the strata peculiarly accom- 

 panying the coal elsewhere, which have here undergone 

 a change in consequence of the causes already pointed out 

 in describing that island. On this it is fruitless to specu- 

 late further. 



In terminating this comparison of the Clyde islands, 

 it is natural to inquire on what causes the present form of 

 that sestuary depends : to what extent its present shape 

 has resulted from the original disposition of the rocks 

 which form its boundaries, and how far it may have been 

 influenced by those posterior changes which consist in the 

 removal of portions of the earth's surface. This is at 

 all times an obscure subject; nor is there much satis- 

 faction to be derived from investigating the several pos- 

 sibilities here involved in that question. 



The irregular form, and the complicated nature of the 

 sestuary of the Clyde are such, that it will be convenient to 

 divide it into its two very obvious and dissimilar portions, 

 before attempting to inquire into the probability that either 

 of them has been produced, or materially altered in form, 

 by the action of posterior causes. The Garroch head and 

 the little Cumbray, constitute the natural limit between its 

 narrow and wide parts ; the latter forming a spacious bay, 

 which communicates with the extensive inlet, Loch Fyne. 



If we contemplate this great bay, in which Arran is 

 situated, it will almost be evident that its form has been 

 fundamentally determined by that of the surrounding land ; 

 by the ridges of hills .which constitute its boundaries. 

 This conclusion is founded on their general correspondence 

 to the leading lines of the western shore, and on the 



