BY E. C. ANDREWS. 171 



same condition of things existed off any line in which such islands 

 were found. He allowed his admiration for the simplicity of the 

 explanation of the theory of coral reefs b}^ Darwin to blind him to 

 his own still simpler explanation, which I will here quote.* 



'' ' In the lirst place, speaking generally, the outline of the 

 Great Barrier Reef is parallel to the outline of the north-east 

 coast. The one follows the other in all its curves and flexures with 

 quite sufficient conformabilit}^ to show that the two are connected. 

 This is perceptible even in the small chart attached to this work, 

 but still more remarkably so when the large Admiralty Charts 

 are examined. It is evident that the circumstances that modified 

 the outline of the coast likewise determined the general outline 

 of the reefs. This is nothing else than to sa}', that the outline of 

 the reefs depends upon the depth of the water. Just as in a 

 large and accurate chart of an}' line of coast we should find the 

 boundary of any certain line of soundings, such as 20, 50, or 100 

 fathoms, conforming generally to the outline of the coast, following 

 its larger flexures and more important features; so we find the 

 outline of the Barrier Reefs conforming to the north-east coast 

 of Australia. Granting that the mean slope of the rocks, forming 

 the original sea-bottom of this coast, was tolerably regular and 

 conformable to the slope of the land, it is evident that if we took 

 away the coral reefs and raised the land to any given height as, 

 for instance, 100 fathoms, we should not greatly alter the outline 

 of the coast, but only shift its situation. It would be thrown so 

 much further forward, or towards the east. Now, sujDpose the 

 coast cleared of coral reef, and raised so much that it emerged 

 from the sea just widiin the line of the present Barrier Reef. 

 Then let the reef commence in the shallow water along that shore, 

 and a very slow and gradual depression take place, giving time 

 for the polyps to build up so as to keep near the surface of the 

 water. The result of this action would be the present Barrier 

 with its steep outer slope, and its gradual extension over the 

 sinking rocks that were once dry land within it. Portions that 



*■ Voyage of the " Fly," Vol. i., p. 345. 



