St Helens, MountSt Hel‧ens, Mount /sənt ˈhelənz $ seɪnt-/ 
a volcano in Washington State in the northwestern US, which erupted (erupt ) in 1980 after a quiet period of over a hundred years, sending out ash (=powder produced when something has been burnt) and lava (=hot liquid rock) over a wide area. The large amount of ash in the air affected the weather in many northern parts of the world for some time.
a volcano in Washington State in the northwestern US, which erupted (erupt ) in 1980 after a quiet period of over a hundred years, sending out ash (=powder produced when something has been burnt) and lava (=hot liquid rock) over a wide area. The large amount of ash in the air affected the weather in many northern parts of the world for some time.