HYPOTHETIC SECTION OF THE GREAT BARRIER REEF, AFTER J. B. JUKES. 



a. Sea outside the Barrier, generally unfathomable. 

 h. The actual Barrier. 



c. Clear channel inside the Barrier, generally about 15 or 20 fathoms deep. 



d. The inner reefs, e, shoal channel between the inner reefs and the shore. 



F. The great buttress of calcareous rock, formed of coral and the detritus of corals and shells. 



G. The mainland, formed of granites and other similar rocks. 



N.B. — The proportions are enormously distorted, the perpendicular scale being fifteen or twenty times 

 greater than the horizontal one. 



CHAPTER III. 



THE JIUSTRALIHN GREUT BARRIER REEF, 



r is proposed to devote this chapter to a consideration of the general 

 structure and most probable mode of origin of the Great Barrier 

 Reef of Australia. Of its kind, or, in fact, of any coral edifices in the 

 universe, it represents the most colossal. Built up b}' direct and 

 indirect agencies of soft-fleshed polvps of multitudinous form and colour, 

 it flanks the Queensland coast, excepting for the presence of a 

 few narrow intersecting channels, for a distance ot over twelve 

 hundred miles. 



Its marvellous extent and nature were, as related in the introductory section, first brought 

 into prominent notice through the famous explorations of Captain Cook, for whose earliest 

 account of many of the Barrier's most striking peculiarities, the reader may be referred more 

 particularly to Volume II., 1821 Edition, of his famous "Voyages." The whole coast-line 

 embraced by the Great Barrier Reef, from Sandy Cape to Torres Strait, bristles on the chart 



