NOTES ON THE lQl6 ERUPTION OF MAUN A LOA 471 



nearly to the region where this grades into the great flat — a distance 

 of several miles (see the photographs, Plate VI, a and b). For the 

 most part the steam was clinging to the surface along the line of 

 fissure; but at one point (and possibly a second) it was rising 

 definitely in small volume. Unquestionably this eruption marks 

 a minor rejuvenation in 19 16 of the action of rifting through Loa, 

 and in this upper segment were the orifices, large and small, from 

 which came the outrush of fumes in the morning of May 19. The 

 place, or places, where steam appeared to be rising definitely was 

 well up the slope beyond its transition into the flat. The line of 

 fissuring marked by steam emanation possibly is interrupted, and 

 perhaps is offset en echelon. This could not be determined posi- 

 tively when seen from so considerable a distance. This fissure 

 leads down in line with the primary system of double semicones 

 which stretch across the flat along the rift zone from near Puu o 

 Keokeo. This line of new steam emanation was seen definitely at 

 all times when the upper slopes were in the field of vision. 



THE SOURCE OF FLOW 



The source of flow was found to be a freshly opened rift crack 

 or, more precisely, a long, narrow system of closely spaced parallel 

 cracks. This ran in a direction slightly oblique to that of the 

 broad rift zone, but confined well within the limits of it, for some 

 three miles or more, tending very slightly to the west of north 

 from Puu o Keokeo across the flat toward the summit. Its upper 

 limit was not reached on this reconnaissance. Out of these fresh 

 cracks gushed the molten lava which streamed away toward lands 

 in Kona, and toward Kahuku — the streams dividing at the northern 

 base of the group of old cinder cones at Puu o Keokeo. Only the 

 Kahuku branches were seen on this reconnaissance. 



OBSERVATIONS NEAR THE SOURCE 



Our bivouac for the night of May 30-31 was in the lee of an old 

 triple-peaked, double semicone in the south re-entrant, where its 

 parts straddle an ancient cinder-choked fissure. This cone was 

 elongated in the north-south course of this fissure. It had been 

 the source of an ancient eruption of pahoehoe. This station was 



