PREFACE 



THE following book owes its existence to a collection 

 of papers originally drawn up for the Geological 

 Society. Circumstances, consisting chiefly in their 

 accumulation, induced me to bring the whole into 

 one general view, and to add that which was wanting 

 to render the Work a connected geological account 

 of all the Western islands. 



In carrying this design into execution, it became 

 necessary to re-model the greater number of these 

 detached essays ; on account of the numerous con- 

 nexions existing among the several islands, and 

 the frequent repetitions of similar facts which were 

 discovered by thus approximating them under one 

 collective point of view. Many omissions were thus 

 unavoidably made ; so that, in a great number of cases, 

 the descriptions of individual islands will appear 

 superficial and imperfect, even where they were ori- 

 ginally full. In a topographic view, it would have been 

 desirable to have retained the whole of them entire ; 

 but as the chief interest of such details is rather of 

 a general than a local nature, that accuracy would 

 scarcely have compensated for the tedious length and 

 frequent repetitions which would have resulted from 

 such a procedure. It will however be perceived, 



