Soundings: The Story of the Remarkable Woman Who Mapped the Ocean Floor
by Hali Felt
Henry Holt: 2012 ($30)

Felt's own mother was a freelance magazine illustrator who loved drawing maps. That, the author explains, may be what drew Felt to the story of Marie Tharp, a geologist and cartographer who helped to prove the theory of continental drift. Tharp worked at Columbia University with a team that measured the depth of the ocean by recording sonar pings from ships. She turned the data her colleagues brought back from expeditions at sea into the first detailed maps of the mid-oceanic rift system, which bolstered the idea that the earth's surface was made up of tectonic plates.