104 ON CORAL REEFS AND ISLANDS. 



The Salomon Islands, as far as ascertained, are but sparingly 

 fringed, except the two westernmost, which are said to have large 

 reefs. The peculiar character of these lands is too imperfectly 

 known to allow of onr deducing the cause of so restricted reefs. 

 Off to the north of the Salomon Islands, there are several atolls 

 of considerable size. New Ireland, according to D'Urville, has 

 distant reefs on part of its shores. 



The Admiralty Islands, fan her west, are enclosed by barrier 

 reefs, and beyond this group there are a few lagoon islands. 



The north side of New Guinea is mostly without coral. There 

 are several islands off this coast, which are conical volcanic sum- 

 mits, and one of them, near New Britain, and another (Vulcano), 

 near longitude 145° E., are in action. 



From the facts thus far detailed, the connection between the 

 prevalence or extent of reefs, and the various causes assigned as 

 limiting or promoting their growth, is obvious. The amount of 

 subsidence determines in some cases the distance of barrier reefs 

 from .shores; but it by no means accounts for the difference in 

 their extent in different parts of a single group of islands. Indeed, 

 if this cause be considered alone, every grade of extent, from no 

 subsidence to the largest amount, might in many instances be 

 proved as having occurred on a single island. Of far greater im- 

 portance, as has appeared, is the volcanic character of the land. 

 At whatever time the existing reefs in the Pacific commenced 

 their growth, they began about those of the igneous islands 

 whose fires had become nearly or quite extinct ; and as others in 

 succession were extinguished, these became in their turn the 

 sites of corals, and reefs began to form. Those lands whose 

 volcanoes still burn, are yet without corals, or there are only 

 limited patches on some favored spots. Zoophytes and volca- 

 noes are the land-making agents of the Pacific. The latter pre- 

 pare the way by pouring forth the liquid rock, and building up 

 the lofty summit. Quiet succeeds, and then commences the 

 work of the zoophyte beneath the sea, while verdure covers the 

 exposed heights. 



We may add a few more illustrations from other parts of the 

 coral-reef seas. 



Along the north and northwest, coast of New Holland, there 

 appears to be little or no coral in the Gulf of Carpentaria, while 

 some extensive patches occur on the shores west of this Gulf, as 

 far as the northwest cape in latitude 23° S. 



In the East Indies, there are large, scattered reef-islands, south 

 of Borneo and Celebes, and the west end of New Guinea. The 

 islands of Timor-laut, and Timor, with many of those interme- 

 diate, have large reefs. The Arm Group consists wholly of 

 coral. This sea, from Arm to the islands south of Borneo, is 

 more thriving in corals than any other in the East Indies. 



