KOKO HEAD 49 



conchoiclal tuff. This tuff is continuous around the south side of the 

 cone. At the southern base it is covered by black ashes. Large frag- 

 ments of compact ehrysolitic basalt are found close by, which have 

 probably come from openings, dike like, near the base of the cone. 

 Lines of these fragments extend across the space between the Kokos and 

 up the slope of the western head. Pieces a }^ard across rest upon the 

 tuff. Further examination will probably reveal the presence of dikes 

 like that on Kupikipikio. 



None of the secondary craters thus far discovered surpass the eastern 

 head in the clearness of the double quaquaversal dips. Between the 

 two Koko heads is a circular hole, 800 feet across, which looks like a 

 small crater. The beds dip away from it on all sides, and the walls are 

 stained by a white incrustation. 



The western Koko head is 9,000 feet long, 5,500 feet wide, including 

 the possible crater just mentioned. The eastern portion is a long hill, 

 from 200 to 300 feet high, with numerous blocks of limestone on its sur- 

 face. It is composed of tuff, capped by ash beds. 



Hanauma is a circular bay in the center, 2,500 feet long and 1,750 feet 

 wide, which seems to be the central crater, now entirely worn away on 

 the side toward the ocean, and the dips quaquaversal about it. The 

 highest point near the western end is called Kuamookane, 644 feet. The 

 dip here is toward Hanauma on the inside, but to the southwest toward 

 the outer side of the head on Kawaihoa. Brigham speaks of a small 

 crater, covered with grass, on the west side of Hanauma, and also of 

 blocks of lava on top of Kuumookane, which he suggests may have 

 been carried there by Hawaiians in ancient times for monumental pur- 

 poses. 



Both Koko heads are more or less covered by a deep red soil, showing 

 that a long time has elapsed since the craters have been active. For 3 

 miles the seaward sides of these heads are precipitous, because of the 

 action of the ocean. Interesting inscriptions and burial caves are re- 

 ported recently as found on the greater head. 



I was unable to visit the craters on the Kaneohe peninsula. They are 

 said to be composed of tuff. 



Black Ash 



The city and environs of Honolulu are widely covered by a coarse 

 black ash or sand of volcanic origin. It is so coarse and uniform that 

 it has been utilized for the removal of all sorts of sewage from the houses 

 to the sea. When the population was sparse this material rendered the 

 laying of cement pipes unnecessaiy. as it removed the waste matter in 

 a satisfactory manner. Now that the population has greatly increased, 



