42 



As a geological system has been adopted in 

 this arrangement of rocks, the principles are 

 therefore similar to those of the followers of Wer- 

 ner. But neither the order of the arrangement, 

 nor the number of the substances is the same as 

 those which are to be found in the works of these 

 authors. The experience of the writer has una- 

 voidably led to modifications, often of a very im- 

 portant kind. Of the nature and truth of the 

 facts on which those views are founded, the evi- 

 dence is, for the most part, contained at length, 

 in his papers in the transactions of the Geological 

 Society, and in his description of the Western 

 Islands of Scotland. The extent and minuteness 

 of this various matter, prevented its introduction 

 here ; but it is hoped that the facts in question 

 will not be found at variance with the future ob- 

 servations of geologists in other countries, kow- 

 ever they may differ in many respects from others, 

 often of more antient date, which, from various 

 causes, have commanded greater respect than they 

 will probably be found to deserve. 



Of the convenience or utility arising from 



