414 W. T. BRIGHAM ON THE VOLCANIC PHENOMENA 



The lava of this eruption closely resembles that in the walls of Aliapaakai on Oahu, and 

 like that contains a very large proportion of chrysolite, in some places nearly one half, and 

 in quite large grains. No similar lava is found in Kilauea, but chrysolitic lava has issued in 

 several streams from Mauna Kea in ancient times, and also perhaps from Mauna Loa, if we 

 suppose the large deposits of this lava occasionally found along the coast near Hilo to have 

 proceeded from this mountain. 



In November of the same year, when visited by Prof. Dana, the lava had fallen three 

 hundred and forty feet below the black ledge, or nearly one thousand feet below the highest 

 wall, and only three pools of lava were in action. The Halemaumau was fifteen hundred 

 feet long and a thousand feet wide. The black ledge, three hundred and forty feet from the 

 bottom, was from one to three thousand feet wide, and extended completely around the 

 crater. No flames were visible, and there was but little noise. 1 



In December, and January 1841, Dr. Pickering describes several considerable 

 variations in the surface of the Halemaumau, a hundred feet or more. On the 

 17th of January, two of the pools discharged large quantities of lava over the bottom of 

 the crater. 2 



The next February, Mr. Coan writes as follows : "When within four or five rods 

 of the great lake, unaware of our near proximity to it, we saw directly before us a 

 vast area of what we had supposed to be solid lava moving off to the right and left. We 

 were at first a little startled, not knowing but all was about to float away beneath us, 

 especially as the lavas for a mile back were almost insupportably hot, and gases and 

 steam were escaping from numerous openings. On looking again, we perceived that the 

 whole surface of the lake was from six to fifteen feet above the level of the surrounding 

 lava, although at my last visit, it was from sixty to seventy feet below. Within six 

 feet of this embankment we could see nothing of the lake, and in order to examine 

 it we climbed the precipice some fifty feet. The explanation of this strange condition 

 of things, is this : When the liquid contents of the lake had risen to a level with the 

 brim, there was a constant and gradual boiling over of the viscid mass, but in quantities 

 too small to run off far. Consequently, it solidified on the margin, and thus formed the 

 high rim which confined the lavas. Twice, or at two points while we were there, the 

 liquid flood broke through the rim, and flowed off in a broad, deep channel which con- 

 tinued its flow until we left the volcano. The view was a new one, and thrilling beyond 

 description." 3 



In July, Mr. Coan saw the large lake overflow on every side, spreading over the 



whole southern end of the crater to the base of the black ledge on either side, and 



wholly concealing the outlines of the cauldron. Two deep fissures opened under the ledge 



on either side, nearly encircling that part of the crater, and one of these was two hundred 



feet deep. Soon these yawning gulfs were filled with the overflow of the Halemaumau, and 



in one place the lava "fell in a cascade of fifty feet, producing a scene of terrific sublimity." 



In a letter dated June 25th, 1846, Mr. Coan states that " the great lake is in- 



' tensely active most of the time. The repeated overflowings have elevated the 



central parts of the crater four or five hundred feet since 1840, so that some points are now 



more elevated than the black ledge." 



The Rev. C. S. Lyman visited Kilauea twice this year, and we find from his description 



1 Loc. cit. p. 171. 2 Narrative of the United States Exploring Expedition, vol. iv., p. 178. 3 Loc. cit. p. 178. 



