732 



SCIENCE 



[N. S. Vol. XLIII. No. 1117 



Mount Pelee that destroyed St. Pierre. 

 Luckily in the Hat Creek region there were 

 only a few summer residents. Warned by 

 the noise of the approaching torrent, they 

 escaped to the hills. 



That no one was killed was simply a mat- 

 ter of good fortune on the part of the eleven 

 enthusiasts who early visited the region to 

 make a photographic record. Mr. B. F. 

 Loomis, the veteran photographer of Viola, 

 was among them. 



There were two hot blast eruptions into 

 the Hat Creek country ; one on the night of 

 May 19 and the other on the afternoon of 

 May 22. 



The Loomis party arrived on the scene 

 about noon, May 22, and spent several 

 hours photographing up to the head of Lost 

 Creek, making a record of what was accom- 

 plished by the first blast. They left soon 

 after 3 o 'clock and had scarcely reached the 

 west side of Chaos Crags when the most 

 violent eruption occurred, sending its 

 column of smoke to a height of more than 

 20,000 feet, as seen from the Sacramento 

 Valley, and a hot blast down the slope into 

 the Hat Creek country that would probably 

 have killed the whole party had the erup- 

 tion occurred a few hours earlier. 



At the time of the great outbreak a fis- 

 sure was opened running from the summit 

 northwest about 1,000 feet down the slope 

 toward Chaos Crags. Three vents were 

 opened on this fissure, and the greater por- 

 tion of the volcanic activity during the sum- 

 mer of 1915 was confined to this fissure. 

 G-. W. Olsen, who ascended Lassen Peak 

 October 19, 1915, reported the northwest 

 fissure quiet, but another one active a few 

 hundred feet east of it on the northern rim 

 of the lid. 



Fumaroles have developed at a number of 

 points on the north and west slopes of Las- 

 sen Peak within 800 feet of the summit, but 

 all the violent eruptions have occurred at or 



very near the summit. No fumaroles have 

 appeared on the south and east slopes, the 

 direction of easiest approach, where at lower 

 levels, 5,800 to 7,400 feet, fumaroles and 

 solfataras are such active features at Bum- 

 pass' Hell, the Devil's Kitchen, and Tar- 

 tarus or Boiling Lake. These solfataras 

 within three miles of Lassen Peak have been 

 active with but little change during the last 

 fifty years. They are on the strongest side 

 of Lassen Peak and have not been affected 

 by the eruptions at its summit, 4,000 feet 

 above them. 



The total mass of material transferred 

 from within the mountain to the surface by 

 the explosive and effusive eruptions during 

 the twenty-two months since the beginning 

 of volcanic activity at the summit of Lassen 

 Peak is very small as compared with the 

 results of volcanic eruptions generally, and 

 yet its small size and high point of activity 

 may be important factors in discovering its 

 cause. 



In any discussion as to the cause of the 

 recent eruptions a record of the facts as to 

 time and energy is fundamental. 



The Forest Service at Red Bluff, W. J. 

 Rushing in charge, furnished most of the 

 important data during the summer when 

 the rangers were in the field, but at other 

 times Miss Alice Dines, postmaster at Man- 

 ton, and G. W. Olsen at Chester, both liv- 

 ing in sight of the mountain, supplemented 

 the record. The eruptions have been tabu- 

 lated as to time, intensity and duration, and 

 the tabulation has a more or less evident 

 bearing as to the efficiency of certain causes 

 that may affect the eruptions. 



The variation as to time of day at which 

 eruptions occur is very irregular and one 

 time of day appears about as favorable as 

 another for eruption. Of the 220 eruptions 

 up to the end of January, 1916, 143 oc- 

 curred in the day time, while 77 occurred at 

 night, that is between 7 p.m. and 7 a.m. 



