Consists of works, correspondence, photographs, documents, seismological charts, slides, and printed matter of Harry Hammond Hess. The collection contains papers, articles, reports, lecture notes, on-site field notes, and notebooks of Hess, and professional correspondence with colleagues in academe, the U.S. government, geological organizations, and scientific societies. Much of the collection includes correspondence, memoranda, reports, and printed matter related to his work with the National Academy of Sciences' Space Science Board, which advises the National Aeronautics and Space Administration on scientific matters, and the academy-sponsored Project MOHOLE, which had the objective of drilling a hole through "Moho," the Mohorovicic seismic discontinuity separating the mantle of the earth from its crust. The collection also contains work Hess did for the Office of Naval Research of the Navy Department, including material relating to his theory of continental drift, as well as charts, graphs, reports, photographs, maps, and slides of geological sites pertaining to the Princeton Caribbean Research Project, organized and directed by him, which explored every aspect of Caribbean geology.