94 



Sierra Club Bulletin 



of storm a temporary break in the clouds showed Lassen in an active 

 state on the nineteenth. The eruption during the night of May 20 re- 

 sulted in the flood which swept down Hat Creek on the morning of May 

 21. The first telegraphed reports regarding this eruption told of molten 

 lava flowing down the mountain sides and of streams of mud ejected 

 from the crater itself, but the fact is now well established that the mat- 

 ter actually ejected from the crater consisted largely of rocks and ashes 

 and of very hot steam. 



This eruption was markedly dif¥erent from preceding eruptions in 

 that the column of steam and ash, instead of being projected upward as 

 usual, was directed obliquely down the slope of the mountain. Evidently 

 the throat of the crater had been choked by debris and from under the 

 edge of this lid the explosion forced the steam and highly heated rock 

 and ashes down upon the great mass of snow lying on the northeasterly 

 slope of the mountain ; the resultant rapid melting produced the sudden 

 flood which swept down Hat Creek on the morning of May 2i. The ac- 

 tual damage to the main farming which lies fully twenty miles to the 

 northward of Lassen Peak was greatly exaggerated in the early reports. 

 In fact in the lower valley it is highly probable that the value of the fer- 

 tilizing action of the mud more than compensated for the damage of the 

 flood. But at the foot of the mountain and along the headwaters of Hat 

 and Lost creeks no description nor photographs can adequately express 

 the feeling of desolation experienced when one sees the destruction of 

 the natural features of these valleys. The downward blast leveled the 

 forest as if it were no more than a grain field. That the trees were blown 

 down and not broken off by the flood which followed is shown by Plate 

 CLH, where trees leveled by the blast lie above the highest flood line. 

 The needles of the pine trees standing on the borders of the sharply de- 

 fined path of the blast were killed by the heat of the steam and ashes. 



Another feature of this eruption that has received but scant attention 

 is the narrow fan-shaped belt of rock fragments projected for miles 

 across the country in the direction of the Hat Creek blast. At Hat 

 Mountain fragments ranging in size from dust particles to pieces seven 

 inches long covered the snow on the old crater rim (Plate CLI). At 

 Cinder Cone they were found "as large as hen's eggs" and twenty miles 

 away about the size of ordinary marbles. At Eagle Lake, some forty 

 miles distant from Lassen, the lapilli were of the size of coarse sand. 



At the time of these eruptions the snow on Lassen Peak was so deep 

 that it was not until May 27 that the actual crater was finally reached. 

 In this first party were Mr. David Durst, from Susanville, and Mr. Wil- 

 liam G. Reed and the writer, from the University of California. Even 

 with the skilful guidance of Charley Yori, of Drakesbad, in picking a 

 path among the snowdrifts, which covered rocks and gullies alike, the 

 party was six hours on horseback making the six miles to the little pla- 

 teau at the southeast base of the final peak. 



Having in mind the new chasm which yawned in the middle of the 

 ancient crater, on climbing to the rim we were astounded to see an al- 



