Ch. VI. DISTRIBUTION OF CORAL-REEFS. 
189 
of this great continent, for a space of between 2,000 and 
3,000 miles south of the equator, has undergone an up- 
ward movement during the period of existing marine 
shells ; and the Andes here form the grandest volcanic 
chain in the world. The islands on the north-western 
side of the Pacific, forming the second grandest volcanic 
chain, are very imperfectly known ; but Luzon, in the 
Phillippines, and the Loo Choo islands, have been re- 
cently elevated ; and at Kamtschatka 1 there are exten- 
sive tertiary beds of modern date. The co-existence 
in other parts of the world, of active volcanos with 
upraised beds of a modern origin, will occur to every 
geologist. Nevertheless, until it could be shown that 
volcanos were absent or inactive in subsiding areas, 
the conclusion that their distribution depended on the 
nature of the subterranean movements in progress, 
would have been hazardous. But now, viewing the 
appended map, it may, I think, be considered as 
almost established, that volcanos are often present in 
the areas which have lately risen or are still rising, 
and are invariably absent in those which have lately 
subsided or are still subsiding ; and this, I think, is 
the most important generalisation to which the study 
of coral-reefs has indirectly led me. 2 
On the dimensions and relative positions oj the 
1 Namely, at Sedanka, in lat. 58° N. (Von Buch’s Descript, des 
Isles Canaries, p. 455). 
2 'We may infer from this rule, that at any place where an old 
formation contains interstratified beds of erupted matter, the surface 
of the land or the bed of the sea formed, at the period of eruption, a 
rising, at least not a subsiding area. 
14 
