Mt Jefferson Volcano | John Seach


Oregon, USA

44.692 N, 121.80 W
summit elevation 3199 m

Mt Jefferson is the second highest mountain in Oregon. It is a deeply eroded stratovolcano, which has been active for hundreds of thousands of years.

The largest eruption at the volcano occurred between 100,000 and 35,000 years ago, and produced ashfall as far as present day Arco in southeast Idaho.

The most recent eruption at Mt Jefferson was from a cinder cone on the flank of South Cinder Peak,  when lava flowed west into Lake Marion.

Even though Mt Jefferson volcano has not erupted recently, it is still considered active. Most of the upper slopes of the volcano are less then 100,000 years old.

Mt Jefferson Volcano Eruptions

950 AD?, 4500 BC