432 W. T. BRIGHAM ON THE VOLCANIC PHENOMENA 



Theoretical Formation of the Hawaiian Group. 



In describing the various islands of the group, slight allusion has been made to the theory 

 of their formation, because it was necessary to compare each with all, and especially to 

 examine the active formative processes now going on in some portions of Hawaii. The 

 external appearance of all the islands and their physical history in recent times, so far as 

 known, have been carefully though rapidly reviewed, and it now remains to trace back the 

 history of this group as completely as may be from the record referred to. 



Formative and destructive agencies have worked in succession, and together, to bring the 

 islands to their present condition, and are both still at work on Hawaii. On the other islands 

 the volcanic forces which raised their mountains have ceased to act, and only the destroying 

 forces of the atmosphere alter the external features of the land. It is with the formative 

 processes we have to deal principally, and we may first consider the phases of volcanic action 

 here exhibited. 



The linear direction of volcanic action has long been a recognized fact in geology, and 

 the Hawaiian Islands are fine examples of the result of such action, but it is difficult to 

 determine the extent of the original fissures from which their lines of volcanoes were ejected. 

 According to one theory there are two fissures extending from north-west to south-east, one 

 commencing with Waialeale, and including Konahuanui, Olokui, Haleakala, Kohala, and Kea; 

 the other closely adjacent, reaching from Kaala to Kilauea, including the remaining peaks. 

 The other and more probable theory supposes a west-north-west main fissure, with lateral 

 subordinate fissures. 



Prof. Dana considers "that there were as many separate rents in the origin of the 

 Hawaiian Islands as there are islands. That each rent was widest at its south-east portion. 

 That the south-easternmost rent was the largest, the fires continuing there longest to burn. 

 That the correct order of extinction of the great volcanoes is therefore nearly as follows : — 



" 1. Kauai. 



" 2. Western 06hu, Mauna Kaala. 

 " 3. Western Maui, Mauna Eeka. 

 " 4. Eastern Oahu, Mauna Konahuanui. 

 " 5. North-eastern Hawaii, Mauna Kea. 

 " 6. South-eastern Maui, Mauna Haleakala. 

 " 7. South-eastern Hawaii, Mauna Loa." ' 

 A more extended exploration than Prof. Dana had the opportunity of making, completely 

 confirms this view, enlarging the series as follows : — 



1. Western Kauai, Napali, (Piiuokapele region). 



2. Western Oahu, Mauna Kaala. 



3. Eastern Kauai, Waialeale. 



4. Western Molokai. 



5. Western M£ui, Mauna Eeka. 



6. North-western Hawaii, Mauna Kohala. 



7. Eastern Oahu, Mauna Konahuanui. 



8. Eastern Molokai, Mauna Olokui. 



1 Geol. United Stales Exploring Expedition, p. 282. 



