S. Powers — Volcanic Domes in the Pacific. 269 



An open dome was next formed over Halemaumau and it 

 remained in place from 1872 until 1886. After the catastrophe 

 of 1S6S which drained the lava lake, Halemaumau became 

 active in 1871 and 1872. In October of the latter year the 

 crater had become an immense dome on whose summit were 

 two lava lakes. The descriptions of this dome are imperfect, 

 but it seems probable that the shores of the single lake of March, 

 1872, were elevated by the force of liquid lava below them. 

 Four lakes developed on the dome and the tilted beds surround- 

 ing the lakes changed in height and form with the variations 

 in level of the lakes. In 1880 the dome was regular in form 

 with a number of crags elevated above the top of the dome. 

 With the emptying of the crater in 1886 the remaining portions 

 of the dome, 200 feet in height, collapsed. 



A deep pit with the form of an inverted cone remained after 

 the collapse of March, 1886, but four months later lava 

 returned and the center of the pit had become a steep cone 

 of talus blocks rising 140 feet and partly surrounded by a lava 

 lake. The cone rose with the lava beneath until, by October, 

 1S66, it became a rim of lava blocks 1000 feet in diameter 

 and 250 to 450 feet in height with a central depression. The 

 basin immediately surrounding the cone rose with it by bodily 

 uplift and by flooding 13 so that the cone appeared conspicuously 

 above the walls of the basin. By July, 1888, the walls of the 

 basin had been eliminated and the summit of the cone was 

 158 feet higher than two years previously. The cone persisted 

 until the collapse of 1891. 



The ability of molten basalt to raise a dome over Halemau- 

 mau in 1848, to elevate the floor of the crater adjacent to the 

 open lava lake in 1872. and to elevate a mass of talus into 

 the form of a cone in 1886, is confirmed by an uplift in 1894. 

 On March 21, the entire surface of the brimming lake appeared 

 to be intensely active and agitated. "Suddenly on the north 

 side stones, lava, and 'dust' were thrown high into the air 

 with spouting columns of fire and in the space of less than four 

 minutes the north bank of the lake was tilted to a height of 

 100 feet or more, leaving an abrupt wall over the lake with a 

 steep and broken slope toward the north." 14 The uplifted area 

 was 800 feet long by 400 feet wide. 



One month after the uplift on the edge of Halemaumau the 

 hill began to sink and by July 11 it had leached the level of 



13 Measurements by F. S. Dodge, cited by J. D. Dana, Characteristics of 

 volcanoes, New York, pp. 109-10. 1891. 



14 An observation by Mr. W. E. Castle, cited bv W. T. Brigham, op. cit., 

 pp. 185-G. 



