Isla de San Pablo

The largest of the Pribilof Islands, St. Paul contains numerous young cinder cones. It consists of a 110 km2 area of coalescing small basaltic-to-trachybasaltic shield volcanoes capped by cinder cones. The most widely exposed lava flows originated from vents in the Bogoslof Hill area in the center of the island and a row of cinder cones in the Rush Hill area on the west side. Subaerial activity began about 540,000 years ago and produced a basaltic lava platform. Later eruptions produced a series of monogenetic vents and two small shield volcanoes. Bogoslof Hill and Hutchinson Hill, forming isolated Northeast Point connected by a low narrow isthmus to the rest of the island, were formed during the Pleistocene. The youngest vent is the Fox Hill cinder cone on the western side of the island that produced a lava flow about 3,200 years ago that traveled into the sea at Southwest Point.