U-t James D. Dana on the 



lavas has evidently been going on, as after previous eruptions, 

 although out of sight, deep beneath the solid rock that forms 

 the bottom of Kilauea ; and they have again reached a height 

 that enables them to be distinguished. The mode of progress 

 and of eruption may therefore correspond throughout with 

 the views presented by the author in his Exploring Expedition, 

 Geological Report, and American Journal, vol. ix., 347. Yet 

 it is also possible that the fires of Kilauea are dying out, and 

 that thus the change of condition is to be explained. 



Although the discharges at the summit of MaunaLoa pro- 

 duce no oscillations in the lavas of Kilauea, it may still be 

 possible that the increased activity at the summit, and the di- 

 minished action of the flank crater, during the past few years. 

 may be connected with the same changes below. These 

 changes may consist in some variations in the distribution 

 of the heat, or, more probably, in a variation of size or direc- 

 tion in the openings or channels that serve to supply the 

 water which feeds the fires. 



5. If Kilauea were to become extinct in its present con- 

 dition, no evidence would exist of its former depth, or of the 

 black ledge or shelf which has been so remarkable a feature 

 in this crater. The present depth does not exceed 600 feet 

 — 400 feet less than after the eruption of 1840.* Moreover, 

 as the precipitous rocky walls are wholly free from scoriae 

 and all other signs of recent fires (looking much like bluffs 

 of ordinary stratified rock), there is no evidence as to the 

 great eruptions that have taken place, and only signs of a 

 sort of Solfatara action, without flows of lava over the bot- 

 tom of the confined area. These facts bear on the conclu- 

 sions that might be deduced from the existing features of 

 extinct volcanoes. 



6. Mr Coan speaks of the lavas as flowing from an orifice 

 in a broad stream down the mountain. It is probable that 

 fissures opening to the fires below were continued at intervals 

 along the course of the eruption, and that these afforded 

 accessions to the fiery flood. Such was the case in 1840, 

 and the three tufa hills at Nanawale, on the sea-coast, mark 



■•' : The centra] portions of ihe crater are much more raised than the lateral, 

 :■ them the depth cannot exceed 500 feet. 



