50 C. If. HITCHCOCK — GEOLOGY OF OAHU 



there is a call for an improvement over this primitive method of drain- 

 age. Nevertheless, facts about the distribution of this ash will still be 

 of importance, as it will be years before all parts of the city can be 

 reached by the new sewers. 



The extreme northeastern limit of the black ash is at the base of the 

 Tantalus cone, where it is well exposed along the road for a quarter of a 

 mile. As much as 25 feet thickness of it is presented to view here. 

 Some of it is weathered, and there are numerous small nodules scattered 

 through it, varying in size from grains to a length of two inches. Some 

 parts seem to be consolidated lumps, both black and red. This mate- 

 rial lies at the southeast base of Tantalus, just as if it had been dis- 

 charged from the crater above. Following the road downward, these 

 ashes appear again, perhaps continuously, at the very southwest base of 

 the cone, rising 40 feet above the road. Here they cease, for the ridge 

 is only just wide enough for the road, and the loose material would have 

 been shed, as it fell from the air, like gravel from the steep roofs of a 

 house. The ash reappears above a reservoir, and, except at a spot about 

 1,000 feet high, it continues through the eucalyptus forest down to the 

 lowest great curve in the road on the spur of the mountain, about 500 

 feet above the sea. It is wanting between this curve and Punchbowl, 

 but it is continuous down to the Lunalilo house, on the eastern slope of 

 the spur. I did not observe any of this sand on the more western spur 

 from Tantalus. 



The spur running down to Kakea and Roundtop toward Makiki is 

 covered by this sand, to the obscuration of the underlying rock, nearly 

 all the way from Tantalus. A small pond east of Kakea, seemingly an 

 old crater, is sometimes spoken of as the source of the great flood of ash, 

 as it is continuous from it over the top of Kakea, 1,460 feet high, and all 

 the neighboring summits. All these hills have rounded slopes, as if they 

 had been deluged by showers of sand. It poured down the Manoa slope 

 as far as to the residence of Mrs S. N. Castle. Roundtop, 1,062 feet, is 

 overlaid by the same material, and everything is covered down to Wilder 

 avenue and beyond. The road from Punahou up to Manoa valley and 

 the north side of Rocky hill shows it nearly everywhere. From Oahu 

 college along the base of the hills sloping down from Tantalus and around 

 the base of Punchbowl the amount of this ash reaches its maximum 

 thickness. 



The following statements give the thickness of this material as found 

 in sinking artesian wells, none being mentioned east of Punahou. At 

 the Woodlawn dairy, corner of Bingham and Alexander streets, there 

 is 10 feet of soil, 20 of sandy clay underlain by 20 of black ash. At the 

 ice works, one mile west, there are 10 feet of ash under 4 feet of soil. 



