380 PICTURESQUE SKETCHES 



CHAPTER XVI. 



GENERAL CONSIDERATIONS CONCERNING THE RESULTS OF GEOLOGICAL 

 INVESTIGATION. 



No one can properly consider the nature of geo- 

 logical researches, and the extent to which they indi- 

 cate the ancient history of the globe and its inha- 

 bitants, without being struck by the simplicity and 

 grandeur of the great plan of creation, and the adap- 

 tation of certain typical forms of organic life to a vast 

 variety of different conditions, examples of which 

 seem to have been introduced in regular order from 

 the beginning of the world till now. In the pre- 

 ceding pages I have endeavoured to give, in the 

 way of narrative, an idea of some detached but 

 characteristic events of this history, and a number 

 of sketches of the different epochs, or times when the 

 conditions were most peculiar and most instructive. 



In carrying out this object, however, I have fre- 

 quently been forced to dwell rather upon the diffe- 

 rences than the analogies that may be traced in the 

 structure and adaptation of successive groups, and 

 have directed attention so often, and in so marked a 

 manner, to these differences, that some of my readers 

 perhaps might over-estimate their importance, did I 

 not now, in summing up the nature and value of the 

 evidence already given in detail, explain how far such 

 an impression may be considered correct. In the 

 present concluding chapter, therefore, I propose to 



