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The Atlantis Massif or Seamount is bounded to the east by the slow-spreadingMid-Atlantic Ridge, and to the south by the Atlantis Fracture Zone. It rises14,000 feet from the seafloor and is a bit larger than the Cascade Volcano Mt.Rainier. It was formed by faulting rather than volcanic activity. The Lost Cityvent field is located near the top on crust that is 1.5 million year old.