AGASSIZ: THE GREAT BARRIER REEF OF AUSTRALIA. 103 



Guinea, 1 or eroded the archipelago lying between them and the chan- 

 nels of moderate depth separating the islands and flats which have 

 been cut by the tides, currents, and action of the sea. 



Beyond the 100 fathom line there are a number of detached reefs, 

 which seem to indicate the existence of very extensive plateaus of 

 moderate depths extending off the continental plateau of the Great 

 Barrier Reef, as, for instance, off Swain Reefs : the Saumarez Reefs ; in 

 the channel separating them from the continental plateau, 199 fathoms 

 is indicated ; in the latitude of Port Denison, 230 fathoms is the 

 greatest depth found in the channel 120 miles wide separating Marion 

 Reef from the continental slope. 



In the latitude of Fliuders Pass to Cook's Passage there is a channel 

 of about sixty miles in width, varying from about 600 fathoms to 1,300 

 fathoms, which separates an immense triangular plateau, bounded to the 

 eastward by the 1,000 fathom line, 250 miles by about the same base 

 with a depth varying from 800 to 300 fathoms, upon which crop out a 

 number of reefs : the Flinders Reef, Flora Reef, Herald Cays, Holmes 

 Reef, Osprey Reef, Diana Bank, Willis Group, Magdelaine Cays, Tre- 

 gosse, and Lilian islands and reefs. Unfortunately no soundings exist 

 to show whether these banks are connected, and are parts of a single 

 plateau, or are separated by deep channels. 



THE GREAT BARRIER REEF. 



We may now proceed with the description of the coral reef flats and 

 patches, which we examined on our way from from Breaksea Spit to the 

 Lizard Islands » (Plates XXIV., XXV., XXVII. to XXXIV.). 



1 See the conclusions of an interesting paper by Professor Haddon on the geo- 

 logical relationship of Queensland and New Guinea, (Transactions of the Royal 

 Irish Academy, 1894, Vol. XXX. p. 467,) and descriptions and sketches of some 

 of the reefs in the Torres Strait scattered through his account of the geology 

 of the Strait, he. cit., page 420 and following. 



2 Professor E. S. Dana published an extract from a letter to him dated Cook- 

 town, Queensland, May 16, in the September number of " The American Journal 

 of Science," 1896, p. 340, giving a summary of the results obtained during my 

 visit to the Great Barrier Reef. 



The steamer " Croydon " of the A. U. S. N. Co. was chartered for my explora- 

 tion of the Great Barrier Reef. Dr. W. McM. Woodworth and Mr. A. G. Mayer 

 accompanied me as assistants. We carried a complete photographic apparatus and 

 an extensive outfit for pelagic fishing in the way of surface as well as of deep-sea 

 Tanner nets, with the usual apparatus for sounding in moderate depths. All this, 



