BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 28, pp. 501-514, PLS. 29-33 SEPTEMBER 21, 1917 



TECTOOTC LINES IN THE HAWAIIAN ISLANDS ^ 



BY SIDNEY POWERS 



{Presented before the Society December 30, 1915) 



CONTENTS 



Page 



Introduction 501 



Spacing of volcanoes 501 



Normal faulting 508 



Summary 514 



Intkoduction 



During the past eighty years the Hawaiian Islands have been visited by 

 various geologists, few of whom saw all the islands of the group or re- 

 mained on the islands for any considerable length of time. Certain of 

 the tectonic features of the islands have received only scant attention, 

 while others have never been examined. It is the purpose of this paper 

 to call attention to those features which have not been described as well 

 as to offer suggestions concerning those previously noted. Various the- 

 ories which have been proposed to account for the alignment of the vol- 

 canoes, both active and extinct, and for their age relations, are reviewed 

 in the light of a recent reconnaissance on every island of the group. 



Spacing oe Volcanoes 



A notable alignment and spacing of the volcanoes in the island groups 

 of the Pacific was noted at an early date by Dana in the Hawaiian Islands 

 and by Darwin in the Galapagos. Many similar lines have since been 

 noted, as in Java, and many suggestions have been made concerning the 

 origin and significance of the phenomena. 



On the Hawaiian Islands the long extinct volcano which built the island 

 of Kauai on one end of the inhabited chain of islands and the active 

 Mauna Loa and Kilauea on the other end led Dana to point out that the 

 volcanoes had arisen along a rent in the floor of the Pacific Ocean, and to 

 suggest that the order of activity had been : Kauai, western Oahu, west- 

 ern Maui, eastern Oahu, northwestern Hawaii, southwestern Maui, and 



1 Manuscript received by the Secretary of the Society October 3, 1916. 



(501) 



