472 C. H. HITCHCOCK GEOLOGY OF DIAMOND HEAD, OAHU 



have issued from the cone, but there is a figure showing how the tufa in 

 one locality has been altered by contact with a heated stream of basalt 

 flowing out of it. One can recognize the actual conditions in the view 

 taken of the cone from Koko head, there being the central cone, the sur- 

 rounding limestone, and the later basaltic flow from Kupikipikio. 



Views of C. E. Dutton 



Captain Dutton writes as follows about Diamond head :* 



"It is composed of cinders and tuff, and is in fact an immense cinder cone. 

 Within it is a very large crater, more than a mile across. Its rim is a sharp 

 edge which forms a complete circle, and though higher in some portions than in 

 others, it is nowhere broken down. . . . The outer flanks of the cone are 

 scored upon all sides with little ravines, which give it the aspect often pre- 

 sented by the fronts of the Bad Lands cliffs of Dakota or of the plateau 

 country. The cone is situated close to the sea which washes the foot of its 

 southern slope. As we pass around the flank we find a mass of strata com- 

 posed of consolidated coral sand, which is strongly cross-bedded. The highest 

 visible exposure of this 'coral rock' is about 200 feet above the sea. That it 

 formed once a wave-washed beach just beneath the surface of the ocean is 

 self-evident." 



He then speaks of its age as very much more recent than that of the 

 mountains of the Koolau range, and also mentions its similarity to 

 Punchbowl and Koko head. 



Notes on the Tertiary Geology of Oahil by W. H. Dall 



These notes were appended to my paper on the geology of Oahu cited 

 above. Doctor Dall examined the lower slopes on the south and east sides 

 of the Head, not ascending it more than 100 feet. "The conclusion to 

 which I came/' said he (page 58), "was that the whole mass of Diamond 

 head had been slowly deposited in comparatively shallow water and grad- 

 ually elevated without being subjected to notable flexure. The ejection 

 of material at first must have been intermittent, with long quiescent 

 periods to enable the shore to have been repopulated with mollusks and 

 corals. The later layers may have been more frequently ejected, as indi- 

 cated by the absence of perfect fossils, or of any fossils, by the thinner 

 calcareous and the heavier tuffaceous layers." 



Also on page 60 : 



"To sum up, it is concluded that the reef -rock of Pearl Harbor and Diamond 

 Head limestones are of late Tertiary age, which may correspond to the Plio- 

 cene of west American shores, or even be somewhat earlier, and in the local- 



* Fourth Annual Report of the U. S. Geol. Survey, 1884, pp. 217-218. 



