508 Miocene Continent. 



during the Upper Cretaceous period Wales sunk almost 

 entirely beneath the sea. 



I omit any detailed mention of the phenomena 

 connected with the depositions of the freshwater and 

 marine Eocene strata because at present this subject is 

 not essential to my argument. 



The Miocene period of old Europe was essentially 

 a continental one. Important disturbances of strata 

 brought it to a close, at all events physically, in what 

 is now the centre of Europe ; and the formations partly 

 formed in the great fresh-water lakes that lay at the 

 bases of the older Alps were, after consolidation, heaved 

 up to form new mountains along the flanks of the 

 ancient range ; and all the length of the Jura, and far 

 beyond to the north-east, was elevated by disturbance 

 of the Jurassic, Cretaceous, and Miocene strata. The 

 broad valley of the lowlands of Switzerland began 

 then to be established, long afterwards to be over- 

 spread by the huge glaciers that abutted on the Jura, 

 deepened the valleys, and scooped out all the rock- 

 bound lakes. 



One marked effect of this extremely important 

 elevation, after Miocene times, of so much of the centre 

 of Europe was, that the flat, or nearly flat-lying 

 Secondary formations that now form great part of 

 France and England (then united), were so far affected 

 by the renewed upheaval of the Alps and Jura that they 

 were to a great extent tilted, at low angles, to the 

 north-ivest. That circumstance gave the initial north- 

 westerly direction to the flow of so many of the exist- 

 ing rivers of France, and led them to excavate the 

 valleys in which they run, including the upper tribu- 

 taries of the Loire and Seine, the Seine itself, the 

 Marne, the Oise, and many more of smaller size ; and 



