ROMANCE OF DEPTHS OF THE SEA 95 



called the " mud-line/' a line that limits the 

 terrigenous deposits everywhere surrounding dry 

 land. Having reached this limit we must pro- 

 ceed warily, for at the mud-line, at an average 

 depth of 100 fathoms, we shall find ourselves at 

 the edge of the continental shelf, that rim which 

 extends seaward to a varying distance from all 

 land areas, the rim on which Great Britain rests. 

 Beyond lies the continental slope, a precipice more 

 or less abrupt and more or less precipitate, descend- 

 ing by steep declines or terraced cliffs until depths 

 of 2,000 fathoms are reached. 



The deepest ocean-pit as yet sounded lies in the 

 Pacific. It is 31,614 feet deep, thus surpassing 

 by 2,612 feet the height to which Mount Everest 

 rises above the mean ocean level. Roughly 

 speaking, the heights to which the higher moun- 

 tains rise above sea-level are paralleled by the 

 depths to which the deepest " deeps " sink below 

 that level. Yet, as has often been pointed out, 

 these inequalities are negligible as compared with 

 the diameter of the earth, and could we shrivel 

 up our globe to the size of an orange, mountain 

 ranges and abysmal depths would be no more 

 prominent than the rugosities of the orange-skin. 

 It may be added that if all the elevations on the 



