404 SUMMARY OF WORK. 



admitted the validity of his reasoning. There re- 

 mained, indeed, differences of opinion as to the in- 

 tensity of the operations by which the denudation had 

 been effected. The followers of Lyell would not admit 

 that the observed facts demanded the existence of 

 larger rivers and more powerful floods than might be 

 witnessed at the present time, while Prestwich was 

 always prepared to find that the geological agents had 

 worked on a grander scale in former times than they 

 do now. But the fundamental fact, that the valleys of 

 the south-east of England and the north-west of France 

 had been carved out by the action of the rivers that 

 drain them, was now accepted without further demur. 



To Prestwich, therefore, must be assigned a not in- 

 considerable share in promoting the advance made 

 during the last thirty years in the investigation of 

 the history of terrestrial topography. He continued 

 to interest himself in the subject up to the end of his 

 life. Some of his last contributions to science dealt 

 with the carving out of the river- valleys around his 

 home at Shoreham and in the neighbouring district of 

 the Weald [123-125]. 



The geologists of the British Islands have always 

 been foremost in their recognition of the place of the 

 ocean among the agents of terrestrial change. Prest- 

 wich followed the national instinct when, in his Presi- 

 dential Address to the Geological Society in 1871, he 

 seized the opportunity, then offered by the expeditions 

 of the Lightning and Porcupine, to review the pro- 

 gress of inquiry into the life of the deep sea and its 

 relations to geological history [74], while at the 

 same time he called attention to the geological signif- 

 icance of the distribution of temperature in the ocean. 

 This latter department of oceanography especially en- 



