312 Branner — Geology of the Hawaiian Idands. 



became active after the excavation of the Niiuaiui A'^alley that 

 leads down to the city of Honohihi, and also after the removal 

 of the northern half of the volcanic cone of which these moun- 

 tains are the remnant, the cinders having; fallen upon the steep 

 — ahnost vertical — face of the bluffs on both sides of the Pali. 

 The road down the north face of the mountain cuts these tuff 

 beds at many places. 



The eminence in the JS'uuanu Yalley on the west side of the 

 road and less than half way from the Pali to Honolulu is also a 

 crater. This crater, also mentioned by Mr. Bishop, is likewise 

 necessarily newer than the Nuuanu Valley in which it is situ- 

 ated. I should add here that I quite agree with Mr. Bishop 

 and with Major Dutton that subaerial erosion is quite compe- 

 tent to explain the more rapid wearing away of the north side 

 of the Pali. 



A small crater next to Kokohead. — The most interesting of 

 the small craters examined on Oahu is one at the east base of 



10 



Sections exposed on the east side of Kokohead showing old gullies filled 



with tuff. 



the great Kokohead crater at the east end of the island. Its 

 chief interest is in the great quantity of coral blown out and 

 now mingled with its tuffs, and in its age relation to the Koko- 

 head crater. The Kokohead crater is newer than the basalt of 

 the great mountain ranges, for its tuffs overlap the basalt at the 

 west base of Kokohead. The small crater at the east base of 

 Kokohead did not come into existence until Kokohead had 

 ceased to be active and its sides had been deeply scored by 

 erosion. This is shown by the fact that gulches on the east 

 face of Kokohead were filled by the coral-laden materials blown 

 from the smaller crater. These latei' materials extend half way 

 up to the summit of Kokohead. The accompanying section is 

 made from a photograph of one of these refilled gulches. This 

 line of separation between the two series of tuffs is clearly 

 visible at many places. Aside from the structural relations the 

 two series are readily distinguishable by the great amount of 

 coral and other calcareous materials in the newer while none is 

 recognizable in the older series. 



