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Hess circulated seafloor spreading in 1960, drawing on Tharp’s mapping.

The Claim

In 1960, American geophysicist Harry H. Hess proposed the seafloor spreading theory using evidence from Marie Tharp's seafloor maps.

Verified by Lenz ·

The Short Version

The historical record supports this account. Reliable references say Hess developed and circulated the seafloor-spreading hypothesis in 1960, then formally published it in 1962. Reputable summaries also link his reasoning to Marie Tharp’s seafloor mapping, especially evidence from the mid-ocean ridge and rift valley, although her maps were not his only input.

Caveats

  • Some references reserve 1962 for Hess’s formal publication; 1960 usually refers to proposal or circulation of the idea.
  • Tharp’s seafloor maps were important evidence, but Hess also relied on other oceanographic observations.
  • Institutional sources such as USGS, Britannica, Smithsonian, and PBS are stronger than social-media or crowd-edited references.

The Receipts

  1. Marie Tharp: Mapping the Ocean Floor

    Library of Congress Blogs

  2. Harry Hammond Hess: Spreading the seafloor

    U.S. Geological Survey

  3. How the Ocean Floor Helped Seal the Deal for Plate Tectonics

    Smithsonian Ocean

  4. Plate tectonics - Hess's Model, Seafloor Spreading, Continental Drift

    Encyclopaedia Britannica

  5. Marie Tharp, 86; Pioneering Maps Altered Views on Seafloor Geology

    Los Angeles Times

  6. Seafloor spreading | Evidence & Process

    Encyclopaedia Britannica

  7. Developing the theory

    U.S. Geological Survey

  8. About Marie Tharp | Mapping the Ocean Floor and Plate Tectonics

    Britannica

  9. People and Discoveries: Hess proposes sea-floor spreading

    PBS

  10. Marie Tharp’s Adventures in Mapping the Seafloor, In Her Own Words

    Lamont-Doherty Earth Observatory

+ 16 more sources — see the full list on Lenz

Filed Under

Harry H. HessMarie TharpSeafloor Spreading Theory