Volcano.
Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is part of the Cascade Range. The mountain is well known for its catastrophic eruption in 1980 which dramatically changed its landscape.
Volcanic mountain.
People thought that Mount St. Helens was just a mountain until it had a volcanic eruption in 2004 when 400 meters of the top of the mountain blew off.
Mount St Helens is a composite cone (strato) volcano.
Volcano
Like most stratovolcanoes, Mount St Helens alternates between explosive and effusive eruptions.
Mount St. Helens, an active stratovolcano, is of the composite type.
There are many including Mount St Helens, Mount Rainier, Mount Fuji, and Mount Vesuvius.
It's an active stratovolcano
subduction
Mount St. Helens is a active volcano, in the Washington State.
Mount St. Helens was known as "Louwala-Clough" ("smoking mountain") by the Indians of the Northwest. Captain George Vancouver of the British Royal Navy named it Mount St. Helens in 1792, after his friend Alleyne Fitzherbert, 1st Baron St. Helens. Mount St. Helens is commonly misspelled in a half-dozen ways. For more background on the spelling and history of the volcano, see the link below.