Motonori Matuyama
Life. Matuyama was born at Uyeda (now Usa) in Japan, the son of a Zen abbot, Tengai Sumiye. In 1910 he was adopted by the Matsuyama (松山) family, and he married their daughter, Matsuye Matsuyama. About 1926, in conformity with a then new convention of transliteration, he altered the romanization of his adoptive family name. Matuyama was educated at the University of Hiroshima and Kyoto Imperial University, where he was appointed to a lectureship in 1913. After spending the period 1919–21 at the University of Chicago working with Thomas C. Chamberlin studying ice, he returned to Japan and  was made professor of theoretical geology at Kyoto Imperial University in 1922. He conducted a gravity survey of Japan during the period 1927–32, extending this to also cover Korea and Manchuria, and studied marine gravity using the Vening–Meinesz pendulum apparatus in a submarine. While rocks had earlier been found with polarities opposite to the present field and the hypothesis advanced that the field had reversed in the past, Matuyama was the first to conduct a disciplined study of the hypothesis. In 1926 he began collecting basalt specimens in Manchuria and Japan, and in 1929 published a paper showing that  there was a clear correlation between the polarity and the stratigraphic position. He remarked that the Earth's field had been reversed in the early Pleistocene age and older, and that it had later changed to the present polarity. This reversed polarity, particularly as shown by the rocks of the ocean floor, provided crucial evidence for the sea floor spreading hypothesis of Harry H. Hess. Matuyama served the Kyoto Imperial University as dean of the Faculty of Science from June 1936 until December 1937; he retired from teaching in 1944 and was made professor emeritus in 1946. In May 1949 , Matuyama was appointed the founding president of Yamaguchi University (N.B. the University transliterated his family name as Matsuyama). In 1950 he was elected a fellow of the Japan Academy. Legacy. The transition, about 0.78 Ma, to "normal" polarity (i.e., that of the present Earth's field) is the "Brunhes-Matuyama" or "Matuyama-Brunhes" reversal. At the 1973 Burg Wartenstein Symposium, it was recommended that “The beginning of the Middle Pleistocene should be so defined as to either coincide with or be closely linked to the boundary between the Matuyama Reversed Epoch and the Brunhes Normal Epoch of paleomagnetic chronology”. This  was finalized in 2020, when the Executive Committee of the International Union of Geological Sciences officially ratified the Global Boundary Stratotype Section and Point (GSSP) defining the base of the Chibanian Stage and Middle Pleistocene Subseries at the Chiba section, Japan, using the "Matuyama-Brunhes reversal" as a marker. The boundary, about 2.58 Ma, between the "Gauss Normal Chron" and the "Matuyama Reversed Chron" is known as the "Gauss-Matuyama reversal". Matsuyama Rocks, in Crystal Sound, Antarctica, are named in his honour and his work on ice crystals.