Oceanographers patrolling the mid-Atlantic in a miniature research submarine have stumbled onto a spectacular deep-sea garden of hot springs and towering spires they nicknamed the "Lost City." "If this were on land," Duke University geologist Jeff Karson said, "it would be a national park."The scientists spotted the formations on Dec. 4 more than 3,200 feet below the frigid, stormy Atlantic during a monthlong expedition to explore a submerged mountain.