keywords: helens lava crater dome stone
text: Mount St. Helens''Fin' May Be Splitting The stone "fin" on the new lava lobe inside the crater at Mount St. Helens seems to be starting to split. The fin, which is about 200 feet tall and 300 feet wide, is building on the new lava dome, which is about 1,600 feet in diameter and 400 feet high.