604 GEOLOGY, 



of cones of the Cascade Range, and in others. I^ess often, volcanoes 

 are bunched irregularly, as in some of the groups of volcanic islands 

 of the Pacific (Fig. 460). 



Relations of Volcanoes. 



1. Relations to rising and sinking surfaces. — So far as observations 

 cover this point, the area immediately adjacent to active volcanoes 

 is rising (Button). This is shown by raised beaches, terraces, coral 

 deposits, etc. Whether this is wholly due to the expansional effect 

 of the heating of the subterrane by the rising lava, or whether it has a 

 wider significance, is not known. If a broader view is taken, it does not 

 appear that there are sufficient data to connect volcanic action ex- 

 clusively with either the rising or the sinking of the general surface. It 

 is certain that the great mountain ranges and plateaus in which so much 

 of the more recent volcanic action has taken place have been recently 

 elevated relatively, but they have also undergone more or less of oscil- 

 lation, involving some relative depression. The question whether 

 the Pacific basin as a whole has been relatively elevated or depressed 

 in modern times is a mooted one. Darwin^ and Dana,^ as the result of 

 their early studies on its coral deposits and on other phenomena, con- 

 cluded that the Pacific was a sinking area, but this view has been recently 

 challenged by Murray ^ and Agassiz ^ with at least some measure of 

 success. From the fiords on the borders of the Pacific and other physical 

 phenomena, the inference has been drawn that relative sinking of the 

 land has recently taken place. Raised beaches on the coasts are inter- 

 preted as indicating a relative rise of the land or a sinking of some ocean 

 basin, for the withdrawal of the waters can only be the result of increas- 

 ing the capacity of the oceanic basin as a whole. The most probable 

 view is that the general areas of present and recent volcanic action are 

 partly rising areas and partly sinking areas, and that movement of 

 either kind may be connected with the extrusion of the lavas. The 

 rising and sinking are but complementary phases of a deformation of 

 the earth's body, and involve a readjustment of stresses within the 



^ Structure and Distribution of Coral Islands. 

 2 Corals and Coral Islands. 



sProc. Roy. Soc. Edin., Vol. X, pp. 505-18, and Vol. XVII, pp. 79-109; Nature, 

 Vol. XXXII, p. 613; Narrative Chal. Exp., Vol. I, pp. 781-2. 

 * Bull. Mus. Comp. Zool, Vol. XVII, 1889. 



