600 



GEOLOGY. 



presence of chlorine in the volcanic emanations has been cited in sup- 

 port of this position. When critically examined, however, the argu- 

 ment from distribution is not very strong; for the volcanoes are not 

 distributed equally or proportionately about the several oceans, as if 

 dependent on them. Volcanoes are especially numerous around and 

 within the Pacific, the greatest of the oceans, and this might seem a 

 favorable instance, but thej^ are also numerous around and within the 

 Mediterranean, a relatively small body of water. Volcanoes are not 

 especially abundant in or about the margins of the Atlantic. 



Fig. 460. — Volcanoes in the Pacific. Jones Relief Globe 

 R. T. Chan.berlin.) 



(Photo, bv 



If volcanoes were dependent upon proximity to the sea, the relation 

 should be close in the past as well as in the present, but this does not 

 seem to be true. There has recently been much volcanic activity in the 

 plateau region of western America at long distances from the Pacific 

 basin. Even on the plains east of the Rocky Mountains notable vol- 

 canic action took place. There were also volcanoes in the interior of 

 Asia and of Africa. 



