SOURCES OF HAWAIIAN VOLCANIC ASH 491 



cause the spongy nature of this ash will allow the access of air to support 

 the combustion. 



It is often dangerous to traverse the forests above the plantations on 

 horseback, because the animals unexpectedly plunge into unseen deep 

 holes and break their legs. Surveyors find it impracticable to carry sup- 

 plies to their workmen by direct routes over these soils and necessarily 

 make wide detours. 



In traveling from Kilauea southwesterly through Kau this ash first 

 appears in small isolated areas 4 miles from the volcano, and then in- 

 creases in amount and importance, and is more noticeable about the 

 "Halfway House." Between this and Pahala certain piles of it, as at 

 the level of 1,800 feet, resemble terraces. It is the material supporting 

 the Pahala sugar plantations. It has been covered at various places in 

 Kau by flows of pahoehoe. An isolated hill of this sort near the tram- 

 way a mile or more northeast from Punaluu harbor is conspicuous. As 

 a rule, the lands near the sealevel have either lost this ash by rain erosion 

 or it is covered by the later lava flows. Most of the peaks in the Mohokea 

 area are capped by the ash, though it is recognized most abundantly near 

 the southeast margin. 



The promontory called Kahuku point, South Cape, and Ka Lae is like- 

 wise covered by this ash, and has attained the thickness of 10 feet, sepa- 

 rated into two parts by a thin seam of earth. The late eruptions of 1868 

 and 1887 destroyed the continuity of this deposit between Kahuku and 

 Kona. 



Mr Emerson has discussed the problem of the source of the aerial erup- 

 tion, and the writer has referred to the same question in a paper on the 

 volcanic phenomena in Hawaii.* 



King Umr's road is referred to as giving evidence of the presence of 

 those ashes for three and a half centuries. He occupied a tract of land 

 between Mauna Loa and Hualalei, where some of the edifices constructed 

 by him were figured by Admiral Wilkes and are still to be seen. The 

 road ran north and south, parallel to the shore of Kona, 7 or 8 miles 

 distant, to a natural amphitheater on the southern slope of Puu o Keo- 

 keo, where immense crowds of Hawaiians gathered to witness the cock 

 fights. The pens still stand as they were in Unifs day. The road over 

 this ash is said to be only two or three feet wide. If a mule traversing 

 this path deviated but a few feet on either side he would sink down to his 

 girth and flounder helplessly. If a shower of pumice or lapilli had fallen 

 since the days of Umi, the road and the pens would have been swept away 

 or covered up. Hence we must regard the ash deposit as the latest forma- 

 tion of the neighborhood, though still several centuries old. 



* Bull. Geol. Soc. Am., vol. 12, p. 83. 



