168 HUTTONIAN THEORY 



marble, and even in fusing it, and found that it then 

 acted vigorously on other rocks. These admirable 

 researches, which laid the foundations of experimental 

 geology, constitute not the least memorable of the 

 services rendered by the Huttonian school to the 

 progress of science. 



Clear as was the insight and sagacious the inferences 

 of these great masters in regard to the history of the 

 globe, their vision was necessarily limited by the com- 

 paratively narrow range of ascertained fact which up 

 to their time had been established. They taught men 

 to recognise that the present world is built of the 

 ruins of an earlier one, and they explained with ad- 

 mirable perspicacity the operation of the processes 

 whereby the degradation and renovation of land are 

 brought about. But they never dreamed that a long 

 and orderly series of such successive destructions and 

 renewals had taken place, and had left their records 

 in the crust of the earth. They never imagined that 

 from these records it would be possible to establish 

 a determinate chronology that could be read every- 

 where, and applied to the elucidation of the remotest 

 quarter of the globe. It was by the memorable obser- 

 vations and generalisations of William Smith that this 

 vast extension of our knowledge of the past history 

 of the earth became possible. While the Scottish 

 philosophers were building up their theory here, 

 Smith was quietly ascertaining by extended journeys 

 that the stratified rocks of the west of England occur 

 in a definite sequence, and that each well-marked 

 group of them can be discriminated from the others 

 and identified across the country by means of its 



