Findings reported from the first ever detailed exploration of the Gakkel Ridge—the northernmost segment of the worldwide mid-ocean ridge system that snakes for 1,100 miles (1,800 kilometers) beneath the Arctic Ocean—underscore the waiting discoveries on the frontiers of Earth science. For decades scientists longingly eyed the Gakkel Ridge. But since it lies beneath a cover of sea ice, access to it has been limited. Apart from a single submarine study, much of what was known about the undersea region's geology was extrapolated from studies of other, more accessible, ocean ridges. [snip]But based on rock samples dredged from the ocean floor...