EXPLANATION OF PHENOMENA. 3i>5 



to this hypothesis, but it seemed to me clearly to 

 explain the reason of both the general form of the 

 Great Barrier and its particular departure from 

 that form. 



In the first 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 

 conformability to shew 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 

 say, that the outline of the reefs depends upon the 

 depth of the water. Just as in a large and accurate 

 chart of any line of coast we should find the boun- 

 dary of any certain line of soundings, such as 

 twenty, fifty, or one hundred 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 



