73 THE COEAL KEEPS OF THE 



that of the Archipelago itself, and the physical 

 appearance of the other islands leads me to helieve 

 that the same rock prevails there also. 



One of the most remarkahle features connected 

 with the Louisiade Archipelago is the manner in 

 which its shores are protected by the coral reefs 

 which have frequently been alluded to in the pre- 

 ceding pages. The principal of these are good 

 examples of that kind distinguished by the name of 

 barrier reefs. Rossel Reef has already been de- 

 scribed, and the only other large one of this descrip- 

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

 partially encirchng 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 water ; thence, however, the edge of a 

 bank of soundings (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 again above water, and passing 

 to the northward of the Calvados Group, reaches as 

 far as the northern entrance to Coral Haven, enclos- 

 ing nearly aU the high islands of the Archipelago. 

 The expanse of water inside when not occupied by 

 land usually exhibits a depth of from 15 to 30 



