"344 The Ohio Journal of Science [Vol. XX, No. 8, 



place when the motion ceased. The conical form is, of course, 

 merely due to the subsequent rattling down of the shattered 

 fragments to form slopes standing at the angle of repose for such 

 materials. 



The thin layer of debris spread evenly over the ground 

 represents, on this view, the more fluid material, the lubricating 

 matrix, which bound together the more solid portions of the 

 slide sufficiently to permit the whole to act as a homogeneous 

 mass expending its energy as a unit, rather than as a bunch of 

 separate rocks, each dependent on its own individual momentum 

 to overcome the friction that opposed its movement. 



Whether this hypothesis has any basis in fact or not could 

 probably be determined only by observation of such a slide in 

 action, but one further circumstance was observed which lends 

 it some probability, namely, this: Some of the cones are 

 composed of the same sort of material throughout. When 

 that material is lava bowlders, the fact is not particularly 

 striking, but one finds occasionally a cone composed exclusively 

 of broken up sandstone. Since there is in the slide, taken as a 

 whole, only a very small percentage of sandstone, a good sized 

 mound of it seems to be most reasonabl}^ interpreted as the 

 remains of a single large block which though thoroughly broken 

 up, was not scattered by its journey down the valley. (See 

 page 352.) 



THE SURPRISING LIQUIDITY OF THE SLIDE. 



In almost every feature of this remarkable mass that one 

 •examines, he sees clear evidence of a liquidity that is nothing 

 short of astounding in view of the materials of which it is com- 

 posed. From whatever aspect one considers the phenomenon 

 thoughtfully, his speculations are sure to be brought back to the 

 problem of accounting for this surprising behavior. 



If the slide had been composed entirely of soft material like 

 much of that at the terminus, its liquidity would be easy of 

 ■comprehension. For in the spring of the year, when the erup- 

 tion and in all probability the slide also occurred, such material 

 becomes thoroughly saturated with snow water and is so nearly 

 liquid that nothing but an initial impulse is needed to send it 

 rolling off the hillside at any time. In climbing the mountain 

 directly above the slide we found considerable ground where 

 we sank nearly to our knees during the period when the snow 

 was going off. Much of the material of the terminal portion of 



