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



The area covered by the debris may be provisionally stated 

 as approximating four square miles. Of the quantity of material 

 that fell away we are not in a position to make even a very 

 intelligent guess, since we know neither the original contours 

 of the cliff, nor can we tell how deeply the debris covers the 

 ground. From the statements of the thickness of other slides 

 given below, it appears conservative, however, to estimate the 

 average thickness as ten yards. On this basis the cubage of the 

 mass would be in the neighborhood of 120,000,000 yards. 



CONE STUDDED SURFACE BELIEVED TO BE CHARACTERISTIC OF 



VERY VIOLENT LANDSLIDES. 



No features of this great landslide are more striking, or 

 arouse more universal speculation as to their nature and sig- 

 nificance than the remarkable conical piles with which its sur- 

 face is so thickly studded. The general texts on physiography 

 in common use make no mention of such topographic forms. 

 As several of our most experienced geologists with whom I 

 have discussed the matter have assured me that nothing similar 

 has come within their experience, I am inclined to think that 

 they have not been adequately described previously. They are 

 not, however, unique, nor are they confined to this particular 

 landslide. 



From field study of other landslides of the Katmai District, 

 and from an examination of the literature, I am inclined to 

 the opinion that this curious type of cone studded topography 

 is not accidental, but is a characteristic feature of extremely 

 violent landslides generally. 



Noisy Mountain, in the second valley of Katmai River, 

 above the Canyon, had a slide in every way similar to the 

 present. There is a gouged out cliff beneath which is a great 

 tumbled mass of debris spread out over the valley floor, damming 

 the river and forming the upper Katmai Lake. This, too, is 

 thickly covered with the same regular cones. (See page 338). 



Falling Mountain at the margin of the Valley of Ten Thous- 

 and Smokes is a gouged out cliff in every way similar to the other 

 two. But in this case the enormous quantity of rock that 

 has obviously fallen away from the mountain is for the most 

 part covered up by subsequent deposits. Nevertheless, several 

 very perfect cones like those of the other slides protrude from 

 the deposits that fill the valley level full elsewhere. 



