Rev. J. F. Blake — Form of Sedimentary Deposits. 17 



Again, compare the lines c-c and d-d. The first is drawn 

 opposite the mouth of the Loire. Here the space within the 

 100 fathom line is very broad, while the other four lines ^down 

 to 2,000 fathoms are crowded together into a quarter, of the space. 

 The second is drawn outward from the Pyrenees, and the slope is 

 naturally rapid ; but the spaces between the lower contours of 

 1,000 and 2,000 fathoms are together twice as broad as along the first 

 line. Thus the deposits along the west coast of France have caused 

 the continental slope there to be twice as rapid, instead of half as 

 rapid, as it should be in comparison with the north coast of Spain. 



Fig. 3. — Submarine Contour-lines from Ireland to Portugal. 



This apparent dependence of the breadth of the submerged shelf 

 and the crowding together of the lower contour-lines on the existence 

 of mud-bearing rivers, may be found repeated in many parts of the 

 world where it is not obliterated by the redistributing power of 

 the long-shore marine currents. The phenomenon is too universal 

 to be assigned to submergence alone, though submergence in some 

 places may modify or accentuate it, but must be the result of some 

 ever acting but varying cause, such as the building up of new 

 deposits from the materials denuded from the old. 



The special effects upon the contour-lines immediately opposite 

 the mouths of rivers can be demonstrated in many cases. Thus, no 



