Jaggar— YolcanologiG Investigations at Kilauea. 1Y3 



meters) to depression 94 feet (29 meters) revealed shoals over 

 the whole southern arm of the lake (fi^. 9). In the midst of 

 these shoals was a circular sinkhole 60 feet (18 meters) in 

 diameter, which became the scene of a spectacular downpour- 

 ing of the liquid part of the melt, through a river-like channel 

 from the remainder of the lake, across the shoals. This revela- 

 tion of sinkholes, often with vortical whirling (fig. 3), is a 

 common feature of sudden subsidence. Eight minor pits were 

 revealed by the subsidence of February, 1917, four of them 



Fig. 3. 



Fig. 8. Feb. 2, 1915, 8.30 p. m. East joool of Halemaumau, dimensions 

 500 by 200 ft. (153 x 61 m.), from the S.E., looking down. Depression 440 

 ft. (134m.). Lake converted into whirlpool of subsidence over ''Old 

 Faithful" sinkhole, the supply torrent following a circuitous channel from a 

 northern conduit, and entering the sinking pool tangentially as a cascade 

 from the E. Blocks of crust on surface of torrent, " Old Faithful " burst- 

 ing in center of whirl. Photo Jaggar. 



known orifices of inflow for nine months previous, three at 

 known grottoes of downrush, and one a sinkhole under the 

 bottom of the lake. The downfiow holes were in general at 

 the opposite end of the pit from the inlet tubes. At times of 

 rapid rise, however, downfiow is not persistent in the same 

 holes, and the circulation becomes stagnant or reversed. More- 

 over, during rapid subsidence an inlet tube may become a sink- 

 hole (fig. 2)V 



There appears to be no escape from the conclusion, fully 

 borne out by the accounts of the older writers,^ that the lava 



*Dana Lake, New Lake, 1880 to 1890, Brigham, loc. cit., Hitchcock, 

 ''Hawaii and its Volcanoes," 1909. 



[Text continued on p. 183.^ 



