VOLCANIC ACTIVITY OF LASSEN PEAK 305 



of being gradually liberaU'd during the six months, been freed during a 

 few minutes, the results would undoubtedly have been comparable to 

 those at Bandai-San. The point, however, is that the difference is 

 qualitative merely and that the nature and magnitude of the eruptions 

 of Lassen Peak fully justify classing them as volcanic. 



A study of the tabular summary of the eruptions gives little upon 

 which to base an oi3inion as to whether the future will bring a fresh 

 lava flow or whether there is being formed a new solfataric basin. The 

 longest period of quiescence was from July 18 to August 10, twenty- 

 three days. The eruptions in November, so far as observations have 

 been made, do not differ materially from those in June. The fact that 

 Soupan Hot Springs, Morgan Hot Springs and those in Hot Springs 

 Valley are situated in valleys at so much lower levels than the new 

 crater, and are apparently unconnected with Lassen, suggests the idea 

 that the recent activity was due to a column of lava working its way 

 upward along the core of the main peak and that this lava may yet issue 

 as a surface flow. It is confessed, however, that the idea is based more 

 on hope than on any scientific data. A visit in July to Bumpass' Hell 

 showed a crater-like depression filled with hot springs, boiling mud pots, 

 and solfataras, yet it is situated on the crc-st of a high ridge, some two 

 or three thousand feet above Hot Springs V^alley and Morgan Hot 

 Springs. The longest diameter of the oval depression is about a quarter 

 of a mile and the height of walls and general appearance are similar 

 to those of the old crater on Lassen Peak. There was no indication 

 that fresh lava flows had ever issued from the crater of Bumpass' Hell ; 

 on the contrary, there was strong suggestion that the depression had 

 developed in the old lava by a process the initial stages of which must 

 have strongly resembled the present condition of Lassen Peak. 



If the writer were to offer any forecast it would be that the changes 

 going on at the top of Lassen seem likely to form a solfataric basin of 

 the" same general character as that of Bumpass' Hell. However, wdiile 

 there is volcanic life there is a possibility of renewed lava flows. j\Iean- 

 time the physiographer has an opportunity of seeing within the United 

 States, at least one phase of volcanic activity and that on a mountain 

 recently occupied by alpine glaciers and standing in a great lava flow 

 studded with minor volcanic cones, many of them almost untouched by 

 erosion — the whole offering a most inviting field for scientific in- 

 vestigation. 



VOL. LXXXVI. — 21. 



