XXX PREFACE. 



which, when once received, will require no fur- 

 ther justification. Hereafter, much may be 

 rescinded which could not now have been omit- 

 ted. Those to whom these reasons are given will 

 thus also be furnished with the means of making- 

 future corrections; since their attentions will be 

 turned to those more questionable points for 

 which the same justification is not offered : they 

 will be led to examine that which the author has 

 not sufficiently considered, and to improve a work, 

 of the deficiencies of which he is far more sensible 

 than his readers will at first be. 



One remark yet remains to be offered on the 

 plan of this work. 



Although, from various geological writings, a 

 more or less just notion, of the general features 

 and dispositions of rocks, and of the systems under 

 which they have been arranged, may be derived, 

 there is no one work in which these can conveni- 

 ently be found, and none in which some of the 

 views here entertained are to be learnt. The 

 mere student, at least, would be at a loss to form 



