STRUCTURE OF CORAL REEFS. 13 L 



Near the middle of the chart is the island Goro ; its shores, 

 excepting the western, are bordered by a fringing reef. The 

 island Angau, south of Goro, is encircled by a coral breakwa- 

 ter, which on the southern and western sides runs far from the 

 shores, and is a proper barrier reef, while on the eastern side, 

 the same reef is attached to the coast and is a fringing reef. 

 From these examples we perceive the close relation of barrier 

 and fringing reefs. While a reef is sometimes quite encircling, 

 in other instances it is interrupted, or wholly wanting, along 

 certain shores ; and occasionally it may be confined to a single 

 point of an island. 



Above Angau lies Nairai ; although a smaller island than 

 Angau, the barrier reef is of greater extent, and stretches off 

 far from the shores. To the eastward of Nairai are Vatu 

 Rem, Chicliia, and JVaiau, other examples of islands fringed 

 around with narrow reefs. Lakemba, a little more to the 

 southward, is also encircled with coral ; but on the east side 

 the reef is a distant barrier. In Aiva, immediately south of 

 Lakemba, the same structure is exemplified; but the coral 

 ring is singularly large for the little spots of land it encloses. 

 The Argo Reef, east of Lakemba, is a still larger barrier, en- 

 circling two points of rock called Bacon's Isles. It is actually 

 a large lagoon island, twenty miles long, with some coral islets 

 in the lagoon, and two of basaltic constitution, of which the 

 largest is only a mile in diameter. Aiva and Lakemba are in 

 fact other lagoon islands, in which the rocky islands of the in- 

 terior bear a larger proportion to the whole area. The same 

 view is further illustrated by comparing the Argo reef with 

 Nairai, Angau, or Moala : these cases differ only in the great- 

 er or less distance of the reef from the shores and the extent 

 of the enclosed land. 



Passing to the large islands Vanua Levu and Viti Levu, 



