lO ninctor's Report for nji6. 



being completely .scorched. Looking acro.ss the flow the scorching 

 of foliage on the lee .side did not appear to be very much greater than 

 on the windward side. Practically all vegetation on the windward 

 side of the flow at a distance of two feet and often less survived. 

 Minor effects on vegetation were the plowing up of sods by great 

 angular blocks of rock pushed forward by the flow ; and the effect 

 of either steani or gases escaping through underground passages 

 along the edge of the flow, which in one case observed caused the 

 destruction of a large koa tree at a considerable distance away from 

 the lava stream. It is hardly necessary to mention that all vege- 

 tation in the course of flowing lava was annihilated. I observed 

 nothing which suggested the effect of poisonous gases, withering 

 being caused by heat, as was indicated by the relative position of 

 scorched and green foliage. Weather conditions during the period 

 of the flow were not particularly favorable for the development of 

 forest fires, and I was not able to ascertain if an}' took place. 



"Along a crack extending from the source of the eruption, 

 which is above Puu o Keokeo, toward the summit of Mauna L,oa, 

 I observed blighting of vegetation which I believe was caused by the 

 emission of poisonous gases. While not impossible that this was 

 caused b}' frost, the relative appearance of the damage done to 

 different bushes bore a decided relation to the distance from the 

 crack. At an estimated distance of three hundred feet on the lee 

 side of this crack bushes of Dodoncea viscosa had blighted leaves; 

 while closer in leaves of Vaccinuiyn pcndiilifloruni and Coprosvia 

 ernodeoides were blighted. The foliage of Cyatliodes Tainciameiae 

 which is needle-like was not affected, but buds of plants rather 

 close to the crack were blighted. In all cases the blighting was 

 slight and the plants probably quickly recovered. 



"At the source of the eruption there is a small area oi pa/ioc- 

 hoe lava ; many of the characteristic cracks of this fresh lava had 

 a whitish discoloration or an otherwise different appearance in 

 color from the rest of the lava, due to the action of escaping gases 

 on the rock surface. This fact is especially mentioned here be- 

 cause it probably bears an important relation to the future invasion 

 of plants. The chemical nature of the surface of the cracks must 

 be somewhat different from the surface rock of ^iXh^r pa/iochoc or 

 aa. I have noticed this surface discoloration in the cracks of all 



old pahochoe flows, but was never quite sure whether it was purel>- 



[202] 



