part 1] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxiii 



know that, from Pliocene times onward, some influence was in 

 operation which caused much instability in the sea-level. This 

 influence is usually assigned in some form or other to the waxing 

 of the Scandinavian ice-sheet, which may be supposed to have 

 initiated changes hj compensative readjustment of the crust, by 

 the abstraction of water from the sea, and by the attraction of its 

 mass ; but into these matters I do not propose to enter. What 

 we know for certain is that the stage of relative elevation was 

 followed by a stage of relative depression, during which the seas 

 around England were brought to a level slightly above that of 

 to-day and remained long enough at that level to carve out a 

 strong coastal shelf in hard rocks. Afterwards, the sea sank away 

 again from this coast-line ; and then the glacial invasion of our 

 low ground began. 



To appreciate the effect of the ensuing glaciation upon the 

 shape of the land, let us consider how England stood when the 

 pre-glaciation liaised Beaches were formed. 



From the relation of the drift-deposits to the solid rocks we can 

 deduce that all the main upland features were then almost as we 

 find them to-day, notwithstanding the sharp modification in detail 

 which they have since undergone. The hill-ranges all held their 

 present relative values in altitude and mass ; the main escarpments 

 had reached positions not appreciably different from their present 

 standing ; the general slope of the land towards the sea-basins was 

 as now ; the trunk-drainage of the uplands, together with most of 

 its branches, was established on lines which have passed down to 

 us without much change ; and the broad distinction between the 

 hill-districts and the lowlands was eveiwwhere that which we still 

 recognize. Before the glaciation the hills as a whole were doubt- 

 less a little higher ; their slopes a little more rugged in some 

 parts and less rugged in others ; and their stream-beds rather more 

 regularly graded : but the changes in the aggregate have been 

 relatively so unimportant that we may imagine that a pre-Glacial 

 hill-man (granting him former existence and an eye for country) 

 would still be able, if resurrected, to find his way about our 

 mountains without much difficulty. 



In the lowlands, however, it is quite another story. There, our 

 ancient man would be in a new world, and completely lost. 

 Just as the upland features are essentially pre-glaciation, so the 

 features of the lowlands are essentially glaciation -products, either 

 directly or indirectly. 



