170 



THE OCEAN. 



The same lij'drulogical laws which determine the formation of banks 

 between two capes are at work to bring about the same result be- 

 tween two islands, or an island and the mainland. On the coasts of 



Fig. 71.— Mouth of the Orne. 



Europe a great number of coast lands have thus lost their insular 

 character, and are changed into peninsulas ; the strait has been gra- 

 dually changed into an isthmus. The peninsula of Giens, between 

 Hyeres and Toulon, presents a remarkable example of this transform- 

 ation. It is connected with the continent by two banks of fine sand, 

 above 3 miles long, each developed in regular curves, which turn 

 their concave faces towards the open sea. Between these two banks 

 stretches the vast lagune of Pesquiers. At the sight of this inland 

 sheet of water and these low shores, hardly elevated above the level of 

 the Mediterranean, one cannot doubt that the mountainous peninsula 

 of Giens was formerly an island like PorqueroUes or Port-Cros, and 

 that the two roads, now separated, of Hyeres and Giens, were formerly 

 one strait. The two uniting banks which joined the ancient island 

 to the coast of Provence, have been raised by the waves in the same 

 manner and on the same plan as the coast ridges of the continent. 

 As to the differences of appearance, they can all be explained by local 

 circumstances. Thus the bank which the isthmus of Giens turns 



