152 LEISURE-TIME STUDIES. 



a fertile soil in which seeds carried by the winds will take 

 root and grow; and ultimately some race of nomads may be 

 found to colonise this strange sea-born land. Thus we 

 observe that a fringing reef affords evidence of either the 

 rising or stationary character of its land ; the barrier reef 

 clearly intimates the subsidence of its foundations ; and the 

 atoll exists as an enduring monument erected over the 

 burial-place of old and forgotten territory. 



Such being Mr. Darwin's views, the feasibility of his 

 theory may be proved by an appeal to the facts and 

 deductions of geological science in particular. First, is it 

 capable of proof that the regions in which atolls and barrier 

 reefs mostly abound, constitute areas of land-subsidence ? 

 One vast area of this kind, extending in the Pacific Ocean 

 for 7000 miles from Pitcairn's Island and the Low Archi- 

 pelago to the Caroline and Pellew Islands, is a region 

 wherein the work of coral-erection proceeds apace ; and 

 between India and Madagascar another area of depression 

 measuring 1500 miles in length has been clearly mapped 

 out. A counter-proof of the correctness of Mr. Darwin's 

 views is afforded by the deductions of geology in ascertain- 

 ing that movements of elevation and depression in the 

 earth's crust do not proceed contemporaneously in the same 

 area; the causes producing the one movement being 

 opposed to those which give origin to the other. Thus 

 volcanic force invariably tends to produce elevation of the 

 earth's crust, and the geologist would therefore esteem it a 

 proof of the correct nature of Mr. Darwin's theory, could it 

 be shown that active volcanoes were absent from the areas 

 in which atoll and barrier reefs exist. Mr. Darwin's reply 

 to this criticism is illustrated by an elaborately prepared 

 map of the distribution of volcanoes, and may be given in 

 his own words. It may " be considered," he says, " as almost 

 established, that volcanoes 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 sub- 

 siding : " whilst he has conclusively shown that the areas of 



