124 MR. A. W. WATERS ON A CHANGE IN 



We have seen how the forces under consideration may 

 have acted in opposite directions ; and a consideration of the 

 recent geological phenomena shows that, while large areas 

 have been elevated, it has not taken place steadily and un- 

 interruptedly, but that there have been elevations and 

 subsidences many times repeated^; so that if we turn to 

 the north of Europe, in Belgium, or to Italy, we find, for a 

 general elevation of a few hundred feet to have taken place 

 since the middle of the Tertiaries, there have been subsi- 

 dences and elevations of many thousand feet in each direc- 

 tion. Now, with the number of forces at work, and the 

 irregular distribution of land and sea, we may say that a 

 reversal of condition in one part could not take the axis 

 back to the same place ; in other words, the poles might 

 tack. 



Might not in this way a cumulative efifect be given to 

 those alterations which it has been shown elevation of large 

 areas can bring about? 



As this is a question for astronomers and physicists 

 rather than geologists to investigate, and they may not so 

 fully appreciate the changes that have taken place in the 

 Tertiary period, it may be advisable to glance at the main 

 phenomena. After the Cretaceous period, the Alps, Andes, 

 Pyrenees, and Himalayas have been elevated, partly in the 

 Eocene, but mostly in the Miocene and also Pliocene. In the 

 Miocene the sea covered more than once the north of Europe, 

 the centre of France, nearly all Italy, and a great part of 

 the rest of South Europe, and a large part of North Africa, 

 a great part of India and South Asia, the centre and east of 

 Australia, much of North and South America. Elevation 

 took place, and also subsidences ; so that we find during part 



* Some similar phenomena may have been caused by alteration of the 

 water-level and not the land ; but for our present purpose we have nothing 

 to do with the cause. 



