Complex sentence: A 15 m high lava spine grew from the Mount St. Helens lava dome in Washington, United States in 1981.The Castle in southwestern British Columbia, is considered to be a lava spine similar to those near Mount Pelée.
Split into simpler sentences: A 15 m high lava spine grew from the Mount St. Helens lava dome in Washington, United States in 1981. There also was a volcano spine on Mount Pelee in Martinque.The Castle in southwestern British Columbia, is considered to be a lava spine similar to those near Mount Pelée.