SUDDEN CHANGES 01' DEPTH. 7 



Abrolhos, near Brazil, such rapid dopes, that the lead on one side of 

 the ship indicated from 4 to 6 fathoms only, while on the other 

 side it marked from 16 to 22 fathoms. Sometimes a special cause 

 explains these abrupt changes of the level. Thus M. de ViUeneuve- 

 Flayosc discovered in the Gulf of Cannes, a spring of fresh water 

 springing from the depths of a kind of well, the sides of which 

 sloped at an angle of 27 degrees. But how can we explain that 

 singular gulf which extends immediately in front of Cape Breton 

 on "the coast of the Landes ? Ought we to attribute its formation 

 to the meeting of the tides, which takes place in the channel of the 



^^ J)t^i}ti cf mart/ lAaa^ S^- falA^. 



Depths under B faihy. 

 jyepths from. 2 fmli- to S^faiJt,. 



Fig. 1.— Gulf of Cape Breton. 



Gulf of Gascony? This is a question whicli it is not yet possible to 



decide. . , 



We can form some notion of tlie submarine tracts by surveying the 

 countries that have emerged from under water at a comparatively 

 recent epoch. The Landes of France, the low lands which have re- 

 placed the Gulf of Poitou, a great part of the Sahara, the pampas^ of 

 La Plata, furnish remarkable examples of the regularity of inclination 



