BULLETIN OF TH'e GEOWgICAL SOCIETY OF AMERICA 

 VOL. 17, PP. 485-496, PLS. 64"66 OCTOBER 18, 1906 



MOHOKEA CALDERA 



BY C. H. HITCHCOCK 



(Presented by title before the Society December 29, 1905) 



CONTENTS 



Page 

 Definition and examples 485 



Location and peculiarities of Mohokea 486 



Mohokea compared with Haleakala 488 



Phases in the development of Hawaiian calderas 489 



Volcanic ash of Hawaii and its source 490 



Order of events in the history of Mohokea 492 



Eruptions of lava from the lower levels 494 



Hualalei 495 



Definition and Examples 



At the New York meeting* of the Society I gave some account of a 

 singular depression on the southwest slope of Manna Loa, calling it a 

 caldera. My information concerning it came primarily from descrip- 

 tions of the topography, given by Mr J. S. Emerson, of the Hawaiian 

 Trigonometrical Survey, which form 'the basis of the official map of 

 Hawaii published in 1901. Mr Emerson had read a paper on the subject 

 before the Social Science Association of Honolulu in October, 1895, 

 which was published in the American Journal of Science in December, 

 1902, under the title of "Some characteristics of Kau." During the past- 

 summer (1905) I have visited the locality, and now proceed to describe 

 the ascertained facts and to draw certain conclusions therefrom. 



A caldera is conceived by Captain C. E. Dutton, who proposed the 

 name, to be an immense depression "formed by the dropping of the 

 mountain crust which once covered a reservoir of lava." The pits of 



* Bull. Geol. Soc. Am., vol. 14, p. 8. 



XLI1I— Bull. Geol. Soc. Am., Vol. 17, 1905 (485) 



