The twin lava domes of the Pitons rise above Soufriere Bay on St. Lucia, forming one of the scenic highlights of the West Indies. Petit Piton (left) and Gros Piton (right) are the eroded plugs of 250,000-year-old dacitic lava domes preceding formation of the 3.5 x 5 km Qualibou caldera about 32-39,000 years ago. The only known Holocene activity at Qualibou was a minor phreatic eruption in the Sulfur Springs thermal area in 1766 CE that ejected a thin ash layer over a wide area.

Photo by Lee Siebert, 1991 (Smithsonian Institution).

This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.

Qualibou