CORAL REEFS. 365 



eastern coast of the Australian continent. Some miles 

 northwards from this Cape begins the Great Barrier Eeef ; 

 the gigantic dimensions of which will be understood by 

 carrying the eye along the Australian coast to Torres Strait 

 and the shores of New Guinea, and learning that this coral 

 reef forms a continuous barrier, separating an inner and 

 shallow coast channel from the deep sea without, and stretch- 

 ing throughout the whole length of the line just described. 

 A mere inspection of degrees of latitude will show that this 

 length exceeds 1,200 miles; and the term continuous is 

 justified by the fact that, except towards the southern ex- 

 tremity of the line, it is broken only by narrow channels 

 or gaps. Still, in strictness, the chain must be considered 

 as a series of individual coral banks of greater or less 

 extent, assuming this definite rectilinear direction parallel 

 to the line of coast. The channel between the barrier thus 

 formed and the mainland contains some scattered reefs ; 

 the outer, or ocean side, dips down precipitously to depths 

 yet unfathomed, leaving a clear sea to the east from 60 to 

 100 miles in width. Beyond this, in the direction of New 

 Caledonia, coral islands or reefs again appear, in unknown 

 number and variety of form, scattered over what we have 

 already noticed under the name of the Coral Sea. 



Our author, in the chapter of his volume before alluded 

 to, well describes the general aspect and character of this 

 great boundary-reef or submarine buttress; the width of 

 which, near the surface, appears to vary from 280 yards to 

 more than a mile. 



If it were to be laid dry, this great barrier would be found to 

 have a considerable resemblance to a gigantic and irregular fortifi- 

 cation a steep glacis crowned with a broken parapet- wall, and 

 carried from one rising ground to another. The tower-like bastions 

 of projecting and detached reefs would increase this resemblance. 

 From examination of our charts it would appear that the normal 

 condition of this long mass of reefs is that the outer barrier should 



