268 8.' Powers — Notes on Hawaiian Petrology. 



lines of cones were seen farther up on the Mauna Loa 

 mountain side. 



The Kilauean pit craters will form another interesting 

 field for investigation when trails are cut through the 

 jungle from the row of pit-craters stretching from 

 Kilauea, Keanakakoi, and Kilauea Iki through Alae Alee, 

 Makaopuhi, and Napau to the row of cones in Puna near 

 the 1840 flows. The transition between pit-crater and 

 cone may be found to be a cone like Puu Huluhulu or the 

 Cone Crater on the Kau Desert, with a large and deep 

 pit in the center. 



Although Eev. Titus Coan was living in Hilo at the 

 time of the 1840 flow, all the flows of that date were not 

 visited by him. Nor were they all visited by "Wilkes, 

 who arrived shortly after the flows ceased moving, if the 

 native traditions are to be believed. These traditions 

 speak of a flow not mapped by Wilkes, between Kei- 

 heiahuiu and Kehena, in Puna, which crossed the Hilo- 

 Kalapana road near Kalapana. The freshness of this 

 flow favors the tradition that it is 1840 in date. » 



Pillow lavas have never been observed on the Hawaiian 

 Islands, unless in a flow seen in cross section by Doctor 

 T. A. Jaggar and the writer between Waipio and Wai- 

 manu valleys on the shore of Hawaii. The small tongues 

 of pahoehoe lava which are so abundant at Kilauea are 

 very different from true pillows seen elsewhere in the 

 field. 15 Unfortunately the lavas which have run into the 

 sea cannot be examined to determine if pillows have been 

 formed by reaction with sea-water. 



Distribution of Rarer Types. 



Trachyte. — In the midst of the floods of olivine basalt 

 which have poured from the slopes of Hualalai and of 

 Mauna Loa, on Hawaii, around the north flank of the 

 former, Dr. Cross found in 1902 the first trachyte, so 

 described, noted on the Hawaiian Islands, 10 but Dr. E. S. 

 Dana had already described a rock of unusual character, 

 later shown to be trachyte, from Puu Launiopoko and 

 from Puu Paupau (Mt. Ball) on West Maui. 17 The next 



15 At Porcupine, Ontario, and near Victoria, Vancouver Island. Professor 

 J. V. Lewis, in a paper on the origin of pillow lavas (Bull. Geol. Soc. Amer., 

 vol. 25, pp. 591-654, 1914), classes these tongues of pahoehoe as pillows. 

 The best photographs published of the tongues are by I. Friedlaender, Ueber 

 die Kleinformen der vulkanischen Produkte, Zeit. f. Vulk., Bd. 1, Hft. 1, 2, 

 4; especially Heft. 4, p. 51, " Zungenf ormes Ende eines Pahoehoe-Strom. ' ' 



16 Jour. Geol., vol. 12, pp. 510-23, 1904. 



17 This Journal, (3), vol. 37, pp. 441-67, 1889. 



