160 HUTTONIAN THEORY 



celebrated by a meeting of the British Association 

 in Edinburgh. 



In choosing from among the many subjects which 

 might properly engage your attention on the present 

 occasion, I have thought that it would not be in- 

 appropriate nor uninteresting to consider the more 

 salient features of that ' Theory,' and to mark how 

 much in certain departments of inquiry has sprung 

 from the fruitful teaching of its author and his 

 associates. 



It was a fundamental doctrine of Hutton and his 

 school that this globe has not always worn the aspect 

 which it bears at present ; that, on the contrary, 

 proofs may everywhere be culled that the land which 

 we now see has been formed out of the wreck of an 

 older land. Among these proofs, the most obvious 

 are supplied by some of the more familiar kinds of 

 rock, which teach us that, though they are now por- 

 tions of the dry land, they were originally sheets of 

 gravel, sand, and mud, which had been worn from 

 the face of long-vanished continents, and after being 

 spread out over the floor of the sea were consoli- 

 dated into compact stone, and were finally broken 

 up and raised once more to form part of the dry 

 land. This cycle of change involved two great 

 systems of natural processes. On the one hand, 

 men were taught that by the action of run- 

 ning water the materials of the solid land are in 

 a state of continual decay and transport to the 

 ocean. On the other hand, the ocean - floor is 

 liable from time to time to be upheaved by some 



