264 PICTURESQUE SKETCHES 



by the production of the central mountain districts 

 of Europe and Asia. In this way was given the 

 first decided tendency to the great east and west 

 line of direction which was afterwards retained dur- 

 ing the elevation of the eastern part of the northern 

 hemisphere. 



How long it was after the deposit of the chalk 

 that these movements commenced, and how long 

 they lasted, whether, as is probable, they began 

 early, and lasted for a very long time, or whether 

 they commenced only when the chalk had become 

 hard and attained its present condition, we are not 

 able yet to assert; but there is little doubt that the 

 great secondary period was locally terminated by dis- 

 turbances connected with the elevation of Europe and 

 Asia, while possibly at this very time deposits were 

 going on in the seas immediately adjacent, and over 

 a great part of the valleys in those two continents. 



These, we believe, are conclusions which Geologists 

 will hardly be inclined to dispute, and they form 

 the outline of a connected history of the revolu- 

 tions of the globe during the secondary epoch. But, 

 besides that part of the history which has immediate 

 reference to British Geology, there are other import- 

 ant facts already known with reference to other dis- 

 tricts. The successive elevation of the Alps, the Pyre- 

 nees, the Carpathians, the Caucasus, and the Hima- 

 layan chain, and even of the Andes, will also be 

 found to bear importantly on the general physical 

 Geology of the epoch, and will tend to clear up 

 many doubts and difficulties that arise in the con- 

 templation of the phenomena as they are presented 

 in our own country and in western Europe. 



