4 GNEISS ISLANDS. GENERAL REMARKS. 



alignement of the limited portions, which alone are 

 amenable to strict investigation ; while it is equally im- 

 possible to cast a more extensive view over the whole, 

 from the interrupted nature of the ground, and the 

 evanescence of the indications of bearing, when points, 

 sufficiently distant to admit of their being comprehended 

 on a large scale, are taken. 



The contemplation of Coll and Tirey, as well as of lona, 

 may perhaps confirm this suspicion, and add weight 

 to the opinion, that the forms of the coasts in the Long 

 Island depend on the direction of the strata. In these 

 islands it is often equally impossible to trace the bearings 

 of the gneiss ; yet in certain places, where granite veins 

 do not interfere, it will hereafter be seen that the beds 

 *are perfectly straight, and that their bearings correspond 

 with the position and leading outlines of the chain. 

 The same circumstance is visible in lona, where the 

 prevailing straightness of the beds enables us to compare 

 them with the general form of the island. But this con- 

 formity, if it be thought not sufficiently established by 

 these arguments, or if it be considered worthy of further 

 confirmation, must be left for the determination of future 

 observers. I shall therefore proceed to describe the 

 several islands in the order which appears most con- 

 venient, reserving all general comparisons till each group 

 has been described. This description will be found to 

 comprise all the principal, and even some of the sub- 

 sidiary islands : those only being omitted which partake of 

 a common character, and present nothing but a repetition 

 of the same appearances. 



