Dietz (English spelling) Robert Sinclair Dietz

American geologist and oceanographer. One of the proponents of the ocean floor spreading theory. Born in Westfield, New Jersey. Earned his degree from the University of Illinois in 1941, and studied under the famous marine geologist Francis Parker Shepard (1897-1985). His research interests include the topography and geology of the ocean floor around continents and the deep sea, as well as ocean slicks. In 1953 (Showa 28), he studied at the University of Tokyo as a Fulbright researcher, and also conducted research at the Hydrographic Department of the Japan Coast Guard. During this time, he studied the underwater propagation of the Myojinsho explosion, which was the cause of the disaster of the Daigo Kaiyo Maru, and is also famous for naming each of the seamounts in the Northwest Pacific Seamount Chain (the Emperor Seamount Chain) after the successive emperors of Japan, such as "Jinmu," "Suizei," "Annei," etc. In 1961, he proposed the sea-floor spreading theory, which states that new ocean floors in the oceans are being created by diverging crusts along mid-ocean ridges. The term "sea-floor spreading" is said to be coined by him. He is one of the proponents of this theory, along with Hess and Hazen. He has served as a professor of geology at Arizona State University since 1977.

[Masao Hanzawa]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

アメリカの地質学者、海洋学者。海洋底拡大説の提唱者の一人。ニュー・ジャージー州ウェストフィールドに生まれる。イリノイ大学で学位を取得（1941）し、有名な海洋地質学者シェパードFrancis Parker Shepard（1897―1985）に師事した。大陸周辺、深海の海底地形や地質、海のスリックslick（海面の縞(しま)模様のこと）などに関する研究がある。1953年（昭和28）、フルブライト研究者として東京大学に留学し、海上保安庁水路部においても研究を行った。このとき第五海洋丸遭難の原因となった明神礁(みょうじんしょう)爆発音の海中における伝播(でんぱ)を研究し、さらに北西太平洋海山列（天皇海山列）の個々の海山に「神武(じんむ)」「綏靖(すいぜい)」「安寧(あんねい)」……と歴代天皇の名をつけたので有名。1961年、大洋の新しい海洋底は中央海嶺(かいれい)に沿う地殻の発散によってつくられつつあるという海洋底拡大説を唱えた。とくに「海洋底拡大」sea-floor spreadingは彼の造語といわれる。ヘス、ヘーゼンとともに、この理論提唱者の一人である。1977年よりアリゾナ州立大学の地質学教授を務めた。

［半澤正男］

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