May 26, 1916] 



SCIENCE 



731 



Professor R. S. Holway, who was one of 

 the first observers to ascend the mountain 

 after the eruption, saw it on May 27, five 

 days after the eruption, and states that 

 "hissing steam was escaping from many 

 cracks and crevices and the shimmering air 

 above all telling of the hot rocks below." 



J. M. Howell's party visited the summit 

 May 30, eight days after the eruption, and 

 Mr. Spaulding reports that 



the heat from the upheaved mass was intense. 

 The air above it shimmered with heat waves like 

 the desert on a boiling summer day. 



That the new lava in the lid at the time 

 of its eruption was so hot at least in spots 

 as to be luminous appears evident and it is 

 probable that the temperature to produce 

 luminosity, say 600° to 1,000° C. would at 

 the same time give to the slowly rising lava 

 such a degree of viscosity as to enable it to 

 adjust itself to its surroundings and over- 

 flow the crater rim. 



Although the lava lid in places appears 

 to be a mass of tumbled rock fragments yet 

 there are large portions of it essentially con- 

 tinuous, as if forced up in viscous condi- 

 tion and broken later as a result of the cool- 

 ing, flowing and subsidence of the mass 

 within the crater. The postmaster at 

 Manton reports that a change was noticed 

 on the summit of the mountain for a few 

 days previous to May 19. A black wedge- 

 shaped mass of lava appeared in the middle 

 of the new crater, getting higher every day, 

 and finally in plain view spilling over 

 through the notch on the west slope. 



Many volcanic bombs were ejected by ex- 

 plosive eruptions during the effusion of the 

 new lava. They range up to five feet or 

 more in diameter and are most abundant at 

 the foot of the steeper portion of the north- 

 west slope. Many of them have a peculiar 

 compact crust with a cracked surface like 

 bread crust, suggesting the name "bread 

 crust bombs, ' ' and they are regarded as the 



luminous ejecta seen in connection with 

 several eruptions by observers from differ- 

 ent points of view. No other portion of the 

 erupted magma afforded such impressive 

 evidence of fusion as the bread-crusted 

 bombs. 



Although the extrusion of the new lava 

 and the formation of the lava lid was the 

 main feature of the great eruptions in May, 

 it was far surpassed in interest and wonder 

 by the remarkable horizontal eruption of 

 the hot blast that devastated Lost and Hat 

 Creeks. 



On the night of May 19, it appears that 

 the body of superheated gases which accu- 

 mulated beneath the lid, forcing it up, 

 escaped from under the edge with terrific 

 force down the deep snow-covered northeast 

 slope of Lassen Peak toward Lost Creek and 

 Hat Creek. The snow was instantly eon- 

 verted into water, and the mighty onrush 

 of water and blast of hot gases swept every- 

 thing before it for more than- ten miles 

 along Lost Creek, forming a devastated belt 

 from a few hundred yards to a mile in 

 width. Meadows were buried beneath finer 

 debris and occasional large boulders broken 

 off from the edge of the lava lid far above. 

 Trees three feet in diameter were broken 

 off or uprooted and the country scoured as 

 by a mighty sand blast. The fine green 

 leaves of the pine trees left standing along 

 the borders of the blast were killed by the 

 heat and turned brown. Locally, on favor- 

 able slopes, the heat was so great that the 

 green leaves were charred. Not only those 

 of the pine, but also those .of the Manzanita, 

 several acres of which, at a distance, had 

 the general appearance of an area swept by 

 a forest fire. In fact it is stated by Mr. 

 Fred Seaborn, of the Forest Service, who 

 was in that region a few days later, that 

 two fires were actually kindled by the 

 eruption. 



This reminds one of the hot blast from 



