CHAPTER XVI. 



THE FORMATION OF LAND BY ANIMAL AGENCIES. — 

 FORAMINIFERAL LAND. 



The operations of the reef-building coral polypes, described 

 in the last chapter, are carried out on a gigantic scale. The 

 Australian barrier-reef, alone, spreads a constantly increasing 

 deposit of coral limestone over an area larger than that of 

 Scotland ; ^ while the totality of the surface, over which coral 

 reefs are spread in the Pacific ocean, exceeds that of Asia. 

 Moreover, reefs and atolls are conspicuous objects, forcing 

 themselves on the attention of the traveller by their beauty 

 and their singularity, and awakening that of the navigator 

 by the dangers which they create. But the conversion of the 

 contents of the ocean into solid rock is constantly taking 

 place, over a still greater area, and probably as rapidly, by 

 agents which are inconspicuous, and, indeed, for the most 

 part, invisible ; not only by reason of their minuteness, but 

 because the results of their work accumulate, not in shallow 

 waters, but at the bottom of the deep sea. Out of s'ght, 

 they would be also out of mind, if various circumstances had 

 not, of late years, led to the careful exploration of the 

 depths of the ocean. 



1 The area of the barrier-reef is estimated to be 33,000 square miles ; 

 that of Scotland is 31,324 square miles. 



1 



