80 INTRODUCTORY REMARKS, &C. 



INTRODUCTORY REMARKS ON THE SANDSTONE 

 ISLANDS. 



THE impossibility of making any arrangement that 

 should perfectly combine geographical with geological 

 convenience, has rendered it necessary to form a separate 

 division for these islands. It is true that many of the 

 Trap islands contain the sandstone in so large a proportion 

 as to have unavoidably led to a partial description of that 

 rock : it has even been necessary, for the sake of illustra- 

 ting that group, to describe two spots, Soa and Longa, which, 

 rigidly considered, should have been arranged in this divi- 

 sion. Still, it is necessary to enter more at large into the 

 examination of this substance, for the purpose of elucida- 

 ting the nature of a series which seems to have escaped atten- 

 tion, and which, from its occupying a large and remarkable 

 portion of the Scottish continent, is of peculiar importance 

 in the history of that country. The geological interest 

 of the subject must atone for the insignificance of the 

 islands included under this general head. 



Many small islands, of similar composition, besides 

 those here enumerated, are found on the western coast ; 

 such as Island Ew, Island Greinord, Martin Island, Longa 

 in Geiioch, and others. Descriptions of these would have 

 been superfluous, as they present no specific interest. 

 Their general characters will be sufficiently explained in 

 the summary which concludes this division, while, in a 

 geographical view, they will also, like many of the minuter 

 islands that have been passed over in this work, find a 

 more appropriate place in a description of that continent 

 to which they are so nearly attached. 



