Dec., 1918] The Great Hot Mud Flow 141 



a hundred feet above sea level. From the east side of the divide 

 the mud flow slopes gently down around the foot, first of Mt. 

 Katmai and then of Knife Peak, till it joins the main valley 

 below the Broken Mountains. 



It is clear that, so far as its gravitational relations are 

 concerned, the mud flow could be accounted for by assuming 

 two points of extrusion at these two summits, but the evidence 

 furnishes no reason for excluding the participation of other 

 vents at any point along the line of the flow. Around Nova- 

 rupta the mud flow has the appearance of being extraordinarily 

 massive, as though a great quantity of it had welled up from 

 that vent. But the appearance of Katmai Pass gives the 

 contrary impression, for there the depth of the flow is slight and 

 there is nothing to indicate that there was ever any great 

 accumulation at that point. Inasmuch as there is clear evi- 

 dence of fumarole action since the eruption, on both sides of 

 the Pass, it appears more probable that the mud in this vicinity 

 welled out of a number of fissures at different levels, rather than 

 from a single large vent at the summit. 



There is no evidence of any of the specific vents from which 

 the mud may have come. If, as is supposed, they were merely 

 fissures in the floor of the Valley, lying below the level of the 

 flow, one would not expect to find them any more than he can 

 locate the unseen springs which feed many a lake. They may 

 be the same as some of the fissures from which the Smokes of 

 the Valley are at present issuing, or they may be stopped up 

 with their own product, the present volcanoes coming from new 

 fissures opened since the mud flow. 



NO EVIDENCE THAT IT ORIGINATED IN EXPLOSIVE ACTION. 



Since the mud resembles a fragmental product, it might be 

 supposed that it originated in explosive action, but, however 

 this may be, there is no evidence of explosions violent enough 

 to have thrown it out against the mountains round about, for, 

 as already pointed out, it is confined to the Valley. So far as 

 there is evidence of its origin, therefore, the indications are that 

 it welled quietly up out of the bowels of the earth. 



It is clearly recognized that current theories of volcanic 

 action do not provide any means of explaining the formation 

 of any such mud flow as we have found in this Valley of Ten 



