72 THE CORAL REEFS OF THE 



that of the Archipelag-o itself, and the physical 

 appearance of the other islands leads me to believe 

 that the same rock prevails there also. 



One of the most remarkable featm^es connected 

 with the Louisiade Archipelag-o is the manner in 

 which its shores are protected by the coral reefs 

 which have frequently been alluded to in the pre- 

 ceding- pag'es. The principal of these are g*ood 

 examples of that kind disting-uished by the name of 

 barrier reefs. Rossel Reef has already been de- 

 scribed^ and the only other larg'e one of this descrip- 

 tion which we saw more than a portion of, is that 

 partially encircling- South East Island at a variable 

 distance from the land^ then passing* to the westward 

 as far as long*. 152° 40'^ where it ceases to shew 

 itself above w ater j thence^ however, the edg-e of a 

 bank of sounding's (represented on the chart by a 

 dotted line) which is suddenly met with in coming- 

 from the deep blue unfathomed water to the south- 

 ward, can be traced in a continued line to the west- 

 ward as far as the Jomard Isles, whence it turns 

 round to the northward for ten miles further, where 

 our examination ended. This last may be con- 

 sidered as a submarine extension of the barrier, which 

 probably reappears ag-ain above water, and passing- 

 to the northward of the Calvados Group, reaches as 

 far as the northern entrance to Coral Haven, enclos- 

 ing- nearly all the hig-h islands of the Archipelag"o. 

 The expanse of water inside when not occupied by 

 land usually exhibits a depth of from 15 to 30 



