40 THE BOTTOM OF THE SEA. 



a declivity wliich may be compared to a rampnit 

 a la Vauban. We may remark here that, coiitrai-y 

 to the general opinion, the aspect of the coast often 

 suggests a false idea of the sea- bottom. When a 

 precipitous mountain descends sheer into the water, 

 we are apt to fancy the sea must be very deep at 

 that spot ; whereas, if we try the plummet, it will 

 most likely be found shallow. Here, again, a sand- 

 bank suggests a low flat shore beyond it, devoid of 



[ T/ie scale on the left hand of the diagram is in metres, but the 

 depths are given in equivalents of feet. '] 



Fig. 12. — Verticiil Section of the Straits of Dover. 



rocks ; we sail on and drop the lead, but cannot touch 

 bottom. Many examples of these deceptive appear- 

 ances must have struck the reader during our rapid 

 survey of the ocean-floor. 



Notwithstanding its steep shores the English 

 Channel is of slight depth. Notwithstanding the 

 cliffs which confront each other on the opposite 

 coasts of England and France, there is so little 

 water in the Straits of Dover, that if the level of 



