i] THE CATEGORIES OF LIFE 7 



on this margin, which is called the ' Continental 

 Shelf.' The slope downwards would be a fairly 

 gradual one so far, but at depths of about perhaps 

 500 fathoms it would begin to become much more 

 steep, and in some parts of the ocean it would be 

 represented by a series of terraced precipices. Beyond 

 these, and at depths of over 1000 fathoms, would be 

 the permanent abysses of the ocean. 



Very strange and unlike anything on the dry 

 land would be this ocean bottom. Beyond the edge 

 of the continental shelf there would be few hills, 

 or valleys, and the slopes downward to greater depths, 

 or upwards to oceanic islands, would be so gradual 

 as to be hardly perceptible to us. Sailors, visualising 

 the sea-bottom from their knowledge of it acquired by 

 soundings, speak of knolls, deeps, etc., but they usually 

 exaggerate the degree of slope actually existing. 

 It is said that there are some fissures on the ocean 

 bottom which resemble the deep river gorges of the 

 land, or bare pinnacles and ridges of primeval rock 

 uncovered by any deposits, but these must be quite 

 exceptional features, and the configuration of the 

 ocean floor probably resembles nothing so much as 

 that of the great prairie lands of the western conti- 

 nents. But nowhere on the land would there be 

 such immense tracts of level surface as those of the 

 beds of the Atlantic, and the greater part of the 

 Pacific, Oceans. 



