CHAP. XIII.] PLEISTOCENE EPOCH. 291 



which followed the deepest submergence was not of uniform 

 extent, and that southern England was raised above the 

 sea, while large parts of northern Britain were still below 

 it, and while Boulder-clays were still being accumulated 

 over them. Those who take this view would probably 

 regard the plateau gravels as deposits formed by snow-fed 

 torrents during this period of elevation. Certainly the 

 phenomena of the river-gravels of this part of England 

 are such as to make it probable that it has never been over- 

 whelmed either by water or ice since an early date in 

 Pleistocene time. 



Without therefore attempting to fix the exact relative 

 dates of the surface deposits of northern and southern 

 England, the inferences to be deduced from a study of the 

 latter region may be put in the form of three propositions. 



(1) That at some period after the greater submergence 

 southern England and Ireland were raised to a much higher 

 level than their present position above the sea, and Britain 

 was united to France. 



(2) That this was followed by a gradual subsidence 

 which, assisted by the action of the sea, was eventually 

 sufficient to disunite England from Ireland and from the 

 Continent. 



(3) That the present geography of Britain was produced 

 by a differential movement, England continuing to sink, 

 while Scotland was raised to its present level. 



To the first of these conclusions, that England formed 

 part of the European continent and Ireland was united to 

 England, and probably also to Scotland, we are led by three 

 distinct lines of evidence, viz., (1) the existence of the 

 mammalian fauna which is known as that of the older 

 cave-earths and river-gravels (later Pleistocene of Professor 

 Dawkins) over the greater part of England and in the south 

 of Ireland ; (2) the position of the older river- gravels in the 

 valleys, and their abrupt termination near the mouths of 



