PREFACE. XXV11 



add that he is, like every one else, willing to 

 imagine himself an unbiassed observer, because, 

 owing to the unexpected circumstances which 

 forced this study on him, he was driven into the 

 field of observation long before he knew what 

 his predecessors in the same path had been doing*. 

 Nor, on a subsequent, and, as he trusts, an im- 

 partial review of those writings, lias he found any 

 reason to suppose that he had been misled by 

 trusting only to that great book which is open to 

 all who will bring to it a desire to learn. 



For most of the local examples whence the 

 conclusions have been drawn, he has been com- 

 pelled to refer to his own observations ; often very 

 unwillingly ; as he is sensible that they must ap- 

 pear to have been derived from too limited a source. 

 Yet, on this subject, it may be said, that through- 

 out the earth, a remarkable consistency, or at 

 least a constant train of analogy and resemblance, 

 is visible in the disposition and relations of rocks; 

 and tlitic in no spot of equally limited extent with 

 Britain, is all the variety which the earth affords, 

 presented in a more condensed and intelligible 



