APPLICATION TO THE GREAT BARRIER. 343 



soncd on with equal clearness and sagacity.* I 

 will confine myself solely to its application to the 

 Great Barrier reef of the north-east coast of Aus- 

 tralia. I tried hard to find any substantial objec- 



* In the New Edinburgh Philosophical Journal, Vol. 34, for 

 the year 1&43, there is an objection brought forward against this 

 hypothesis of much apparent weigbt. The objection is, if coral 

 reefs have really the enormous thickness that the hypothesis 

 would assign to them, why do we not find them among our older 

 formations, where we have the old sea bottoms raised into the 

 air ? My answer to this objection would be, that in none of the 

 older formations, nor, as far as I am aware, in any well known 

 tertiary formation, do we find reef-forming-corals. "We have 

 abundance of fossil corals tbat would grow upon reefs, in their 

 more sheltered portions and inner slopes, or that would live in 

 the hollows of other rocks, or form small fringing reefs, where 

 there was no very heavy surf. But we have no fossil corals at all 

 comparable in size, Btreugth, or weight, with the huge maian- 

 drinae, the massive porites, and ponderous mounds of astraea that 

 compose the great sea-walls of our present " atolls" and large 

 barrier reefs. These gigantic corals are never seen on the inner 

 slopes, or more accessible portions of the reefs, but only in the 

 blocks that lie near its outer edge, where they have been rolled 

 up by heavy gales from its seaward slope. They seem to belong 

 only to the existing order of things, and not to have lived during 

 any of the secondary or early tertiary periods. The present is, 

 so to speak, the coral reef age of the globe. 



The existence of these great corals, however, furnishes to my 

 mind the only objection to Mr. Darwin's hypothesis which is at 

 all a plausible one. May not these, and perhaps other species or 

 genera still more gigantic, live and flourish at greater depths 

 than the corals commonly found about the surface or inner slopes 

 and sheltered portions of coral reefs ? If there should be such 

 corals, and if they formed masses with nearly perpendicular Bides 



