The Lava Plain of the North 



103 



The latest volcanic eruption in the Lassen Peak region, and 

 possibly the latest in the United States south of Alaska, oc- 

 curred at the Cinder Cone, 10 miles northeast of Lassen Peak, 



Photo by R. H. Finch. Courtesy Univ. of Calif. 



FIG. 30. Bumpass Hell, looking west. 



about 200 years ago. Some of the trees killed at that time are 

 still standing. The lava, though very viscous, spread more than 

 a mile from the vent. The lava formed a dam across a small 

 stream in southwestern Lassen County and thus Snag Lake came 

 to be. This lake contains stumps of trees drowned at the time 

 the lake was formed. 



One hundred twenty volcanic vents in the Lassen Peak 

 region have contributed the great mass of lava of which the 

 Lassen Peak Ridge and plateau have been built up, chimneys 

 through which issued from earth's interior countless tons of 

 molten rock. A conical hill or mountain has been built up 

 around each vent or chimney. Some of the eruptions were on 



