THE CLYDE ISLANDS. 501 



the red sandstone was often covered by a great body 

 of alluvial matter which appears to have arisen from its 

 decomposition; remaining in the places in which it was 

 formed. The same feature was then noticed as occurring 

 in Cantyre. It is here indeed even more remarkable; 

 as, independently of those alluvia which are still actually 

 connected with subjacent bodies of the rock in this dis- 

 trict, portions of it are to be found now unconnected 

 with any rock ; occupying the surface, without seeming 

 to have undergone any transportation. From these seve- 

 ral appearances, it may be concluded that the red sand- 

 stone of Cantyre once formed a more continuous mass ; 

 and that its present disjunction is to be traced to those 

 gradual operations, already pointed out in treating of 

 the great Cumbray, and also indicated in Arran, by 

 which extensive tracts of the surface are decomposed, 

 and often removed. The red alluvia appear to be the 

 last remaining indications of the parts that formerly occu- 

 pied the places where they are found ; and it is not 

 difficult to foresee, that in the further progress of time, 

 the present insulated masses of that rock will terminate 

 in that complete decomposition to which they are fast 

 hastening, and ultimately perhaps disappear altogether. 



As the identity of this mass of sandstone, throughout 

 its whole course through Scotland, was shown, from these 

 considerations its original continuity is also in a great de- 

 gree demonstrated ; and thus the islands of the Clyde 

 become reunited to the peninsula of Cantyre, in a geolo- 

 gical sense, as perfectly as they have been shown to be 

 geologically continuous with the much greater tract to 

 the north-east of their position. 



The last rocks which require notice in this general com- 

 parison are those of the trap family. 



In the introduction to the Trap isles, it was remarked 

 that a very common connexion in place was found between 

 those rocks and the secondary strata. That general re- 



