Sect. II. BATE OF GROWTH. 95 



have an equal tendency to upward growth. The infer- 

 ence, therefore, that one reef could not grow to the 

 surface within a given time, because another, not 

 known to be covered with the same species of corals, 

 and not known to be placed under exactly the same 

 conditions, has not within the same time reached the 

 surface, is unsound. 



SECTION SECOND. 

 On the Bate of Growth of Coral-reefs. 



The remark made at the close of the last section, 

 naturally leads to this division of our subject, which 

 has not, I think, hitherto been considered under a 

 right point of view. Ehrenberg 1 has stated that in 

 the Eed Sea, the corals only coat other rocks in a 

 layer from one to two feet in thickness, or at most to a 

 fathom and a-half; and he disbelieves that, in any 

 case, they form by their own proper growth, great 

 masses, stratum over stratum. A nearly similar obser- 

 vation has been made by MM. Quoy and Graimard, 2 

 with respect to the thickness of some upraised beds of 

 coral, which they examined at Timor and some other 

 places. Ehrenberg 3 saw certain large massive corals in 

 the Eed Sea, which he imagines to be of such vast 

 antiquity, that they might have been beheld by 



1 Ehrenberg, as "before cited, pp. 39, 46, and 50. 



2 Annales des Sciences Nat., torn. vi. p. 28, 



3 Ehrenberg, ut sup. p. 42. 



