-±02 Wood — Effects in Mokuaweoweo of the Eruption of 191Jf. 



axes also are slightly upturned so that cutting edges and spiked 

 points characterize the resultant surface. While in a certain 

 sense brittle, this new lava is hard and strong and these points 

 and edges are more than usually sharp. Hence the cutting and 

 rasping effect of this surface, on footwear for example, is more 

 destructive than is commonly the case, even on a-a. 



In different parts of the flow these blades vary from the size 

 of a steel pen to that of a table-knife blade, or even larger 

 over very small patches. They also exhibit differences of 

 individual form and arrangement depending somewhat on the 

 miniature physiographic development of the surface. For 

 example, on the surface in channels of rapid flow they stand 

 almost exactly parallel with the streaming and are long spiky 

 blades, or even spikes, slightly inclined up from the surface as 

 they point down-stream. On rounded, toe-lava projections 

 they are broad, short, very flat blades showing a tendency to 

 radiate in their axial arrangement from some central region of 

 the rounded surface. On broad warped surfaces they have 

 ordinary blade shapes with a slightly divergent arrangement 

 of their axes. The photograph, fig. 9, illustrates the general 

 character of this texture on an ordinary pahoehoe surface. 



These blades sometimes form the surface of thin crusts sep- 

 arated from the thick, dense layers below by a coarsely vesicu- 

 lated stratum from one to six inches thick. But again they 

 make the surface of layers from one to three feet thick, or 

 more, that are relatively dense throughout — in some places 

 very dense indeed for an effusive basalt. 



In nearly all places the surface of this new lava is blue-black 

 tobluish steel-gray in color, but there are numerous patches 

 where thin layers of surface oxides give it the color of gold, or 

 streaked arrangements of color with iris hues. 



North of the cone of 1903 and west of the rift of 1914, see 

 the map (tig. 13), practically all of the floor of 1915 is of lava 

 of this type, whether pahoehoe, or a-a, or an intermediate 

 block-pahoehoe (a sort due to fragmentation with piling while 

 still flowing). It was estimated that there is more pahoehoe 

 than a-a on this part of the floor, and nearly as much block- 

 pahoehoe as a-a. 



This region of the crater floor shows at least one rude, cres- 

 centic, rifting zone which appears to mark approximately the 

 position of the former cliff of the north lunate platform. No 

 differences of general level were observed on opposite sides of 

 this broken zone. Other less continuous, and in all ways less 

 sharply defined zones of rifting were seen nearer the center of 

 the crater. 



Though a few typical " schollendomes," or low, elliptical 

 domes riven along their crest, were seen, this region of the 

 floor is remarkably free from them. But it is characterized 



