PREFACE. XI 



is hoped that the account of the geological topography 

 will generally be found as complete as the present 

 state of the geography of these islands permitted. 

 To render such details rigidly correct, requires a 

 degree of geographical accuracy which is not at 

 present attainable, and an extended scale of engrav- 

 ings which the necessary economy of the plan did 

 not permit. 



As many of the papers which gave rise to this 

 Work, were drawn up at different and distant periods, 

 and with other views; and as some parts were un- 

 avoidably written while the remainder was going 

 through the press, incongruities and repetitions, and 

 probably, contradictions also, will be discovered. On 

 reviewing indeed iany parts of it, after four years, 

 I find much that might be altered and much that 

 might be improved. But the fluctuations of opinion, 

 or the increase of knowledge, to which every observer 

 must be subject, are scarcely greater than those by 

 which the science of geology is now almost daily 

 affected. Had the Work been kept to the Horatian 

 period, it would doubtless have required more altera- 

 tions. Had it been written nine years hence, it might 

 have been even more defective ; as the science might 

 have still further outstripped the acquirements of the 

 author. 



Whatever may happen in this respect, it is still hoped 

 that the facts will prove useful. As far as they have 

 been carefully investigated, they will assist others in 

 laying the foundation of a more accurate and extended 

 knowledge of this subject: even where these state- 

 ments shall prove unfounded, they will stimulate 

 future observers, in examining and controverting them, 



