R. A. Daly — Problems of the Pacific Islands. 165 



The Kilauea vent in southeastern Hawaii has suggested an 

 answer to those questions. At that most instructive of all vol- 

 canoes there is a lake of molten, surging basaltic rock. 

 (Plate III.) The lake is the top of a liquid column extending 

 deep into the earth ; its glowing surface has been almost con- 

 tinuously visible since 1907. Wonderful beyond words is the 

 night view of the exquisitely colored, incandescent billows of 

 molten basalt, as they thrash about the lake. The waves 

 breaking on the lake shore, the ever-varied streaming of the 

 lava, and its periodic, fountain-like uprushes are the effects of 

 the discharge of gas from the earth's interior. Its most 

 important effect, however, appears to be a rapid, convective 

 overturning of the lava, whereby the gas-freed and therefore 

 heavy lava sinks, while fresh, hot lava rushes up to take its 

 place. Such, in brief, is the hypothesis offered in partial ex- 

 planation of the continuance of activity at Kilauea and it may 

 apply generally. During its years of activity the Samoan 

 volcano, Matavann, behaved much like Kilauea. It is a great 

 pity that detailed comparative stncly of these two volcanoes 

 was not made in the field ; a unique opportunity has been 

 lost. 



Kilauea has further suggested that a volcano is a true fur- 

 nace, heat being actually generated near the vent through 

 chemical reactions among the constituents of the lava. 

 Through their quantitative analysis of the conditions at the 

 lava lake, Day and Shepherd, of the Geophysical Laboratory 

 at Washington, have confirmed this hypothesis. 



How far the maintenance of heat supply at active craters is 

 due to convective overturn, to blowpiping by free-moving 

 gases, or to chemical generation in the lava columns, is a com- 

 plex and supremely difficult question. According to present 

 knowledge, Kilauea promises a solution sooner than any other 

 vent. Yet, not only should the existing observatory in Hawaii 

 be supported ; its scientific product should be strengthened and 

 enriched by close, prolonged observation at the other active 

 volcanoes of the Pacific. 



Not less insistent is the question of periodicity, a universal 

 phenomenon in all great volcanoes of the cone-and-crater type. 

 Why is each intermittent, alternately active and dormant ? 

 At times the activity of the Kilauean crater is restricted to a 

 quiet emission of gas and vapor from a small hole in a floor of 

 solid lava. For about eight years the crater of the lofty 

 Mauna Loa, twenty miles from Kilauea, was similarly sleep- 

 ing; until, on the 25th of last November, its molten lavas 

 again appeared, throwing up glowing fountains of liquid 

 basalt, 100 to 300 feet in height. The cause of the intermit- 

 tency of action for volcanoes in general has been suspected at 



