NOTES ON THE igi6 ERUPTION OF MAUN A LOA 485 



end and around the major cones (see the photograph, Plate VI, d), 

 while slag lumps were more characteristically found about the 

 spatter cones and along the northern part of the rift course. 



Also there was suggestion that the ejection of slag lumps con- 

 tinued after the action of pumice ejection was over, but no proof 

 of this could be elicited. 



DISTANT OBSERVATION OF THE UPPER SOURCE 



The upper source of the 1916 eruption, where the outbursts of 

 fumes occurred on May 19, has not yet been visited, so far as the 

 writer is aware. This is a place on the great mountain dome very 

 remote from trails, and travel with horses over the barren, untracked 

 lava is both difficult and dangerous. This source lay between 

 13 and 15 miles from our camp — a distance altogether too great to 

 cover on foot in the short time at our disposal over going so rough 

 as that prevailing within and along the rift belt. 



However, this region could be seen plainly through the clear 

 mountain air from the old cone at the head of the lower rift, at a 

 distance of a little over 9 miles. With binoculars magnifying 

 eight diameters some of its characteristics could be made out. It 

 lay within, and was much elongated parallel to, the axis of the 

 major rift zone. It extended from near the edge of the summit 

 plateau down the somewhat steep upper slope nearly to the great 

 flat which lies north of Puu o Keokeo. It appeared to have a 

 moderate breadth, say a quarter of a mile. Fumes were clinging, 

 or slowly rising, along its axis, probably from a system of fissures 

 (see the photographs, Plate VI, a and b). In two places, appar- 

 ently not far apart, about two-thirds of the way up its course, 

 definite columns of rising fumes could be made out frequently. 

 On one occasion, in the late forenoon of July 3, one of these columns 

 was estimated to reach upward 500 feet before it spread out and 

 dissipated. 



At all times when it was clearly visible the surface of this source 

 area, on both sides of the line of fumes, appeared of very light 

 color, even whitish. It could not be determined whether this was 

 due to the sheen of new pahoehoe, to efflorescence of sulphur or 



