CORAL-REEFS. 177 



from the atoll-formed Appoo reef : and there are two other 

 volcanoes in the map within ninety miles of circles coloured 

 blue. These few cases, which thus offer partial exceptions 

 to the rule, of volcanoes being placed remote from the 

 areas of subsidence, lie either near single and isolated atolls, 

 or near small groups of encircled islands ; and these by our 

 theory can have, in few instances, subsided to the same 

 amount in depth or area, as groups of atolls. There is not 

 one active volcano within several hundred miles of an 

 archipelago, or even a small group of atolls. It is, there- 

 fore, a striking fact that in the Friendly Archipelago, which 

 owes its origin to the elevation of a group of atolls, two 

 volcanoes, and, perhaps, others, are known to be in 

 action : on the other hand, on several of the encircled 

 islands in the Pacific, supposed by our theory to have 

 subsided, there are old craters and streams of lava, which 

 show the effects of past and ancient eruptions. In these 

 cases, it would appear as if the volcanoes had come 

 into action, and had become extinguished on the same 

 spots, according as the elevating or subsiding movements 

 prevailed. 



There are some other coasts on the map, where volcanoes 

 in a state of action concur with proofs of recent elevation, 

 besides those coloured red from being fringed by coral- 

 reefs. Thus I hope to show in a future volume, that nearly 

 the whole line of the west coast of South America, which 

 forms the greatest volcanic chain in the world, from near 

 the equator for a space of between 2,000 and 3,000 miles 

 southward, has undergone an upward movement during a 

 late geological period. The islands on the north-western 

 shores of the Pacific, which form the second greatest 

 volcanic chain, are very imperfectly known ; but Luzon, in 

 the Philippines, and the Loo Choo Islands, have been 



877 



