Portland lies on top of an extinct volcanic field known as the Boring Lava Field , named after the nearby bedroom community of Boring . The Boring Lava Field has at least 32 cinder cones such as Mount Tabor , and its center lies in southeast Portland . Mount St. Helens , a highly active volcano northeast of the city in Washington state , is easily visible on clear days and is close enough to have dusted the city with volcanic ash after its eruption on May 18 , 1980 . The rocks of the Portland area range in age from late Eocene to more recent eras
eruption on May 18 , 1980 .
1980 eruption of Mount St. Helens
Portland, Oregon