I’ve been meaning to read Soundings, Hali Felt’s biography of Marie Tharp, since it came out in 2012. Since then I’ve seen a flurry of articles, interviews, videos and other tributes concerning Tharp, whose reputation, which grew during her lifetime, continues to grow in the 12 years since her death in 2006 at the age of 86.

The bare bones of Tharp’s story are therefore fairly well known: while mapping the floor of the Atlantic Ocean, she discovered the presence of the Mid-Atlantic Ridge—and, more specifically, its rift valley, providing tangible evidence of continental drift. Because continental drift was at that point considered to be a crackpot theory, it took some doing for Tharp’s discovery to be accepted; and when it was her contributions were to some extent minimized.

While Felt’s book is positioned as a biography, its strength is in the details of that pivotal discovery: how and where it was made, and by whom, and in what context. Tharp’s work was not done in a vacuum, and how and why she was where she was is important. Felt sets the stage for us: not only does she take us through Tharp’s early childhood and rather variegated education and her arrival in 1948 at the Lamont Observatory, she gives us a short history of that Observatory, of the theory of continental drift, of her colleagues—notably her lifelong collaborator (and possibly life partner) Bruce Heezen and Observatory director (and sometime antagonist) Maurice Ewing. More than anything else, Soundings provides context for Tharp’s discovery: by the time we’re done, we know how important it was, and why. We’ve been well briefed.

Physiographic Diagram: Atlantic Ocean

Felt is less successful in building a portrait of Tharp herself. Some areas of her non-work life—her childhood, family and college education, for example—are extremely well covered, but other areas have considerable gaps, particularly those involving her personal life. The nature of Tharp’s relationship with Heezen is only hinted at, as is an early, unsuccessful marriage to someone else. Her later life, supported by a motley gang of eccentrics called Tharpophiles, is also incompletely covered. The elisions, however unintended, are frustrating. I suspect the author was a prisoner of her source material, which in places she follows very closely; I would have liked it if more had been done to fill in the gaps.

Soundings was published in hardcover by Henry Holt in 2012. It’s available in paperback and ebook from Picador.

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Author: Jonathan Crowe

Jonathan Crowe blogs about maps at The Map Room. His essays and reviews have been published by AE, Calafia, The New York Review of Science Fiction, the Ottawa Citizen, Strange Horizons and He lives in Shawville, Quebec.