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



right are of basalt. Above the limestone there is some ash before reach- 

 ing the house. Figure 1, plate 62, shows a ledge of limestone in the 

 midst of the ash, while beyond are the basaltic fragments detached by 

 weathering from the boss. The locality is a field east from the house 

 shown in figure 2, plate 61. The ash was spoken of in my Oahu paper 

 (page 45) as being like the Diamond Head tuff. The tuff and the ash 

 merge into each other at Kupikipikio, and the latter is also extensively 

 spread along the road passing around the north side of Diamond head. 

 Both probably came from the Kupikipikio ejection. 



The limestone is 505 feet thick in the Campbell well on the seashore 

 at the southwest corner of Diamond head, beneath 270 feet of the tuff.* 

 It is thicker here than in any other of the wells of the Honolulu plain. 

 The limestones, earths, and upper basaltic masses lie entirely to the south- 

 west of Koolauloa. Wells sunk near the Makiki reservoir to the depth 

 of 200 feet or more upon this basalt failed to discover any limestone, 

 whence it is inferred that the Tertiary series, penetrated by nearly all 

 the artesian wells in the vicinity of Honolulu, represents a later age, 

 consisting of the coral reefs built upon the volcanics. 



The black Ash 



Considerable labor has been expended in determining the sources of 

 the black ash about Honolulu, and it was concluded that it came from 

 several craters, notably Punchbowl and Tantalus, as well as from Koko 

 head, Diamond head, and Makalapa. A better knowledge of the condi- 

 tions about Diamond head leads to the belief that the ash on its east- 

 ern side came from Kupikipikio. Since my earlier visit a good road 

 has been constructed around the Head, and it has been possible to exam- 

 ine all the rocks with greater care and precision. There are beds of this 

 ash cut by the road on the northeast and north sides of the Head, sloping 

 toward the east. A part of the material has changed its color from black 

 to reddish, due to weathering. It is generally much finer grained than 

 the ash about Honolulu. It has not been observed about Diamond head 

 elsewhere than on the Kupikipikio side, where it would have naturally 

 fallen if ejected from the latter opening, being carried by the prevailing 

 winds so as to fall upon the slope of the former. So also had the ma- 

 terial come from Diamond head we should expect to find some remnants 

 of it at least upon the leeward side. The position of Kupikipikio may 

 be better understood by noticing the dark promontory in the distance in 



* Op cit, p. 28, 



