232 VULCANISM 



the presence of chlorine in the volcanic gases has been urged in sup- 

 port of this view. Volcanoes, however, are not distributed so 

 equably and exclusively about the several oceans as to give this 

 conclusion force. Volcanoes are numerous within and around the 

 Pacific, the greatest of the oceans, and in and around the Mediter- 

 ranean, a much smaller body of water; but they are not especially 

 abundant in or about the Atlantic. On the other hand, there are 

 existing or very recent volcanoes in the interior of Asia, Africa, and 

 America. If volcanoes were dependent upon proximity to the sea, 

 they should have had close relations to it in the past, as much as 

 now; but in recent periods there has been much volcanic activity 

 in western America, far from the sea, and in the heart of Asia and 

 Africa. In older periods, it is still less clear that there was any con- 

 nection between volcanoes and oceans. 



3. Relative to crustal deformations. The distribution of present 

 and recent volcanoes is more suggestively associated with those 

 portions of the crust that have undergone movement in comparatively 

 recent times, or are still moving. The great mountain belt stretching 

 from Cape Horn to Alaska and thence onwards along the east coast 

 of Asia is dotted with active and recently extinct volcanoes. The 

 tortuous zone of mountainous wrinkles about the Mediterranean, 

 and thence eastward to the Polynesian Islands, is another notable 

 volcanic tract. These two belts include the greater number of 

 existing and recent volcanoes on the land. 



4. In latitude. Volcanoes appear to have no specific relation 

 to latitude. Mounts Erebus and Terror amid the ice-mantle of 

 Antarctica, and Mount Hecla in Iceland, as well as the numerous 

 volcanoes of the Aleutian chain, give no ground for supposing that 

 volcanoes shun the frigid zones, while the numerous volcanoes of the 

 equatorial zone imply that they do not avoid the torrid belt. 



5. In curved lines. In the Aleutian and Kurile Islands, and 

 elsewhere, there is a linear arrangement of volcanoes, with appre- 

 ciable curvatures, the convexities of which are turned toward the 

 adjacent ocean. In other cases there is a linear arrangement with- 

 out appreciable curvature, as in the Hawaiian range. In some cases, 

 volcanoes are bunched irregularly, as in some of the groups of vol- 

 canic islands of the Pacific (Fig. 227). 



The relations of volcanoes. A significant feature in connection 

 with volcanoes is the apparent sympathy between adjacent vents 

 in some cases, and their entire independence in others. The recent 



