ti4 CORAL-REEFS. 



flourish at greater depths than between 20 and 30 

 fathoms. 



It has been argued 1 that reefs may possibly rise from 

 very great depths through the means of small corals, first 

 making a platform for the growth of the stronger kinds. 

 This, however, is an arbitrary supposition : it is not always 

 remembered, that in such cases there is an antagonist power 

 in action, namely, the decay of organic bodies, when not 

 protected by a covering of sediment, or by their own rapid 

 growth. We have, moreover, no right to calculate on 

 unlimited time for the accumulation of small organic bodies 

 into great masses. Every fact in geology proclaims that 

 neither the land, nor the bed of the sea retain for indefinite 

 periods the same level. As well might it be imagined that 

 the British Seas would in time become choked up with beds 

 of oysters, or that the numerous small corallines off the 

 inhospitable shores of Tierra del Fuego would in time form 

 a solid and extensive coral-reef. 



1 Journal of 'the Royal Geographical Society, 1831, p. 21S. 



