218 J. I). Dana — History of the Changes in Kilauea. 



Kilauea is situated, like Hilo, in a region of almost daily- 

 mists or rains, and if approaching Hilo in the precipitation, as is 

 probable, over 100 inches of rain fall a year. Tables give over 

 200 inches some years for Hilo. The whole becomes subter- 

 ranean except what is lost by evaporation ; for, owing to the 

 cavernous and fissured rocks, there are no running streams 

 over the eastern or southeastern slopes of the island south of 

 the Wailuku river which comes down from the northwest to 

 Hilo. That which falls into the crater and on its borders gives 

 moisture to the many steaming fissures ; and sometimes it 

 makes a steaming area of the whole. But this part has very 

 little to do with the volcanic action. 



A part of the subterranean waters follow the underground 

 slopes seaward, as shown by copious springs in some places 

 near the shores ; and these also take no part ordinarily in the 

 A^olcanic work. But another part must descend by gravity 

 vertically, or nearly so, and keep on the descent far below the 

 sea level. It has been shown on a former page (p. 16) that 

 much the larger part of the eruptions have occurred in the 

 months from March to June, and this appears to indicate a 

 dependence of the action to some extent, on the abundance of 

 precipitation.* 



Moisture may be gathered also from all moist rocks along 

 the course of the conduit in the depths miles below the reach of 

 superficial waters, as suggested by different writers on vol- 

 canoes. But any dependence on the amount of precipitation 

 would show that this is not its chief source. 



Another source of water is the sea. But sea-water could 

 not ordinarily gain access to the conduit except at depths much 

 below the sea-level, on account of the abundance of subterra- 

 nean island waters pressing downward and outward. Further, 

 no one has yet reported evidence of the presence of marine 

 salts, or chlorides, beyond mere traces, among the saline pro- 

 ducts of Kilauea or Mount Loa after an eruption. 



A third source of moisture is the deep-seated region in or 

 beneath the crust whence the lavas come. Of this we know 

 nothing. The fact that the presence of such moisture below 

 would make this a dangerous earth to live on has been urged 

 against the idea of such a source. 



Since all ordinary action in Kilauea, and also in Mt. Loa, is 

 of the quiet non-seismic kind, the introduction of water into 

 the conduit must be an ordinary and a quiet process, not one 

 of sudden intrusion through fissures. Sudden intrusions may 



* This view with regard to the sources of the waters is sustained by several 

 writers. It is well presented, with explanations at length as to the water line in 

 the volcauic mountains, in a paper on " the Agency of Water in Volcanic Erup- 

 tions," by Prof. Joseph Prestwich, Proc. Roy. Soc, xli, 111. 



