322 THE BEAUTIES OF NATURE CHAP. 



back to the time when that great sheet of 

 fresh water was in connection with the Arctic 

 Ocean, so there is in the character of the 

 Fauna of the Italian lakes, and especially the 

 presence of a Crab in the Lake of Garda, 

 some confirmation of such an idea. Further 

 evidence, however, is necessary before these 

 interesting questions can be definitely an- 

 swered. 



Lastly, some lakes and inland seas seem to 

 be due to even greater cosmical causes. Thus 

 a line inclined ten degrees to the pole be- 

 ginning at Gibraltar would pass through 

 a great chain of inland waters the Medi- 

 terranean, Black Sea, Caspian, Aral, Baikal, 

 and back again through the great American 

 lakes. 



But though many causes have contributed 

 to the original formation and direction of 

 Valleys, their present condition is mainly due 

 to the action of water. When we contemplate 

 such a valley, for example, as that which is 

 called par excellence the " Yalais," we can at 

 first hardly bring ourselves to realise this; 

 but we can trace up valleys, from the little 



