Haiemawnau Lava Lake. 



345 



ence of which was indicated by a mill-race at the surface. 

 However this may be, the cause of the one is the cause of the 

 other, but the island grotto with its cascades falling free must 

 certainly represent the maximum grade of inter-circulation of 

 the lake lava. The cascades would continue to flow for several 

 hours when the action would cease with the rise of the inner 

 level to equilibrium with the rest of the lake, remaining thus 

 until again disturbed by gas action from within. 



Fig. 4. 



Fig. 4. Diagrammatic plan and East- West section of Lava Lake, show- 

 ing scheme of circulation. 



We are now in a position to take a general view of the entire 

 system of circulation as shown diagram matically in fig. 4. The 

 island and its cascade grotto are here omitted as having con- 

 stituted an altogether exceptional phenomenon and to avoid 

 complication, the downflowing phase and its mechanism being 

 represented by a spatter grotto in the east bank of the lake. 



The lava is shown issuing from under the western* bank 



* The west is here placed at the right, as the usual point of view at Hale- 

 mauman is from the north. See fig. 1. 



