THE 



AMERICANJOURNALOFSCIENCE 



[FOURTH SERIES.] 



Akt. XXYIir. — The Great Barrier Reef of Australia ; bj 



W. M. Davis. 



The Great Barrier reef of Australia, which fronts the east- 

 ern coast of Queensland for a distance of over 1,000 miles, has 

 been interpreted according to Darwin's theory by Jukes, the 

 first geologist to study it (1847), and by several later observers, 

 and therefore regarded as a great upgrowth of reef and lagoon 

 deposits upon a slowly subsiding foundation. The lagoon being 

 from 30 to 70 miles wide, a vast thickness has been ascribed to 

 the reef, as in section A, fig. 1. Other observers have denied 

 that Darwin's theory is applicable in explaining this greatest 

 of barrier reefs; thus Gardiner, the most experienced English 

 student of the coral-reef problem, says that the theory of sub- 

 sidence is here "absolutelj^ excluded," and replaces it by the 

 theory of veneering reefs on sea-cut platforms.* This is an 

 impossible theory because the shore line is not clift. Unfortu- 

 nately, in reaching his opinion Gardiner overlooked the indis- 

 putable evidence for submergence, presumably due to subsi- 

 dence, that is ajfforded by the strongly embayed mainland 

 coast, to which Penck first drew attention in 1896. K sample 

 of the coast in latitude 20°, S., is given in fig. 2, reduced from 

 British Admiralty chart ]^o. 347. Several sketches of the 

 mountainous coast and its embayed shore line are given in ^g. 

 3 : sketches A and B are of islands outside of the Whitsunday 

 passage (see ^^. 2) ; sketch D shows the mainland coast of the 

 passage ; sketch C is Magnetic island, near Townsville ; sketch 

 E is a part of the coast south of Cairns. As the sketches were 

 made from the deck of a passing steamer, the embayments are 

 much foreshortened. 



*J. S, Gardiner, The Building of Atolls, Proc. Internat, Congr. Zool., 

 1898, 119-124. 



Am. Jour. Sci. — Fourth Series, Vol. XLIV, No. 263. — November, 1917. 

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