Inconsistent newspaper accounts reported by witnesses from 1850 to 1851 described seeing " fire thrown to a terrible height " and " burning lava running down the sides " in the area of Cinder Cone . As late as 1859 , a witness reported seeing fire in the sky from a distance , attributing it to an eruption . Early geologists and volcanologists who studied the Cinder Cone concluded the last eruption occurred between 1675 and 1700 . After the 1980 eruption of Mount St. Helens , the United States Geological Survey ( USGS ) began reassessing the potential risk of other active volcanic areas in the Cascade Range . Further study of Cinder Cone estimated the last eruption occurred between 1630 and 1670 . Recent tree-ring analysis has placed the date at 1666
1980 eruption
1980 eruption of Mount St. Helens
Lassen Volcanic National Park