Jaggar — Activity of Mauna Loa. 639 



material of consolidation of tills eruption of 1914 will probably 

 prove to be in part a light limu or what Dana called " thread-lace 

 scoria." Such material, often sherry-colored and with iridescent 

 surfaces, the writer collected about hot cracksnear Mokuaweoweo 

 in 1912, this being presumably the summit product of the 1903- 

 1907 activities. There is much limu occurring as small lapilli 

 about the summit area, showing that this material was blown 

 about during recent eruptions, and the central cones in the 

 crater, built in 1903, are largely of pumiceons material. 



The occurrence of gas-impelled and gas-heated fountains of 

 lava foam as the initial manifestation of a rising lava column 

 at the summit of Mauna Loa, 10,000 feet higher than the vent 

 of Kilauea, is more compatible with the possibility of a subter- 

 ranean connection between the conduits of the two volcanoes 

 than would be the case if the Mauna Loa fountains were jets 

 of heavy melt without any sign of gas or flame. It may well 

 be that with the expansion, escape and oxidation of the gases 

 rising as bubbles through the lava, a subterranean cooling and 

 congealing effect determines for the time being the duration 

 of the preliminary phase. There follows a term of accumulation 

 accompanied by some change of state which is less frothy and 

 the final lava flow relieves the accumulated stress and ushers 

 in a repose period. 



The question of sympathy with Kilauea must still be 

 considered an open one. In the long and large, the activities 

 of Kilauea have shown tendency to alternate with the eruptive 

 periods of Mauna Loa, this being especially striking since 1887. 

 The repose period 1908-1913 of Mauna Loa was a time of 

 rise, culmination aud fall in Kilauea. In 1913-1911 Kilauea 

 lava subsided to smoky depths for a year and then came the 

 Mauna Loa outbreak. With this outbreak, however, the 

 Kilauea column gradually rose to a relatively low culmination 

 coincident with the month of Mauna Loa activity and there- 

 after it subsided, but has slightly revived with the solstice of 

 June, 1915. The writer inclines to the belief that future 

 research will demonstrate a complicated sympathy of alter- 

 nation between the two volcanoes dependent upon gas release 

 at one vent impoverishing the other. But the response is not 

 instantaneous and phenomena of what may be called back-kick 

 are to be looked for. Something of this kind may explain the 

 rise of Kilauea in 1914-15, if that rise proves to be temporary. 



Volcano Observatory, Hawaii. 



