Marie Tharp, studying echo soundings, discovers that the Mid-Atlantic Ridge conceals a long rift valley, which turns out to be part of a hidden volcanic rent that girds the global deep.
This underwater mountain range is now called the Mid-Atlantic Ridge, and it was one ... more startling was the central valley ...
Sailing aboard his research vessel, the Calypso, he purposely crossed the mid-Atlantic Ridge and lowered an underwater movie ...