president's address SECTION E. 387 



If vou elect, or are compelled by circumstances, to live in the fighting 

 line, you must expect and prepare for inconveniences, as the rough 

 and tumble of the shift will go on regardless of the presence of non- 

 combatants. The American scientists give a striking picture of the 

 issue of the conflict : — 



*■' The earthquakes of California have been studied for some 

 years (1906) by Messrs. Holden and Perrine, of the Lick Observatoiy, 

 ajid the geology of the State is being revealed through the labours of 

 Messi's. Russell, Diller, and Lawson. Betv^een the Rocky Mountains 

 and the Pacific are the parallel chains of the Sierra Nevada and the 

 Coast Range. Among the Rocky Mountains earthquakes are few and 

 slight; on the eastern slopes of the Sierra Nevada they are more 

 frequent, and, sometimes, as in the Owen's Valley earthquake of 1872, 

 of considerable severity. The Western portion of the Sierra Nevada, 

 the Cascade Range, is remarkably free from earthquakes, though it 

 is worth noting by those who see an intimate relation between volcanic 

 and seismic actions, that it contains the recently extinct cones of 

 Shasta, Mount Hood, and Mount Rainier. Again, the Cuast J^ange, 

 and especially the districts surrounding San Francisco and Los 

 Angeles, is one of the great seismic regions of the globe.. Lastly, to 

 the west of California, the sea-bed deepens rapidly, the contour of 

 4.000 metres lying only a short distance from the land, and from 

 this region many of the strong Californian earthquakes are known to 

 proceed. 



" Recent studies have established a close connection between these 

 earthquakes and the geological structure of the district. Whether the 

 earthquakes take place under the Coast Range or beneath the adjoin- 

 ing ocean, the longer axis of the isoseismal lines are either parallel or 

 pei-pendicular to the sub-oceanic contour-lines, the crust folds of the 

 Coast Range and the long lines of fault of the Pacific sea-board. It 

 is difficult to resist the conclusion that in the Western United States 

 we are presented with mountains in four successive stages of gi'owth. 

 In the Rockies we have ranges so ancient that they have almost 

 ceased to grow; in the Sierra Nevada, to the west, another which is 

 approaching old age; the Coast Ranges are in the stage of youthful, 

 vigorous gTOwth, with the possibility of a long and active life befoi"e 

 them; while still further to the west, and not yet risen above the 

 ocean, there seems to be an embryonic range, of which the San 

 Francisco and other earthquakes are the birth-throes." 



The geology of Central and South America has not been so care^ 

 fully studied, but we may anticipate very similar effects in the many 

 regions of seismic activity. 



On our side of the ocean volcanic eruptions constitute a safety 

 valve and are the main agents in the upheaval or up-building of land. 

 The mighty pile of Fusijama shows us the scale of magnitude of such 

 operations. The pumice^strewn seas of the New Hebrides, the masses 

 of lava poured out unceasingly by the volcano still erupting in Savaii, 

 the terrific blow-out of Tarawera in 1886, which buried 1,800 square 

 miles of country more or less deeply under sand, ash, and tuff, and 

 fragments of the country rock, are examples nearer home. Fortvm- 

 fitely for Australia, it is situated well behind the fighting line, and, 



* "Nature," April 20, 1906. 



