In Japan, studies and researches of the earth started in the late 19th Century after the opening of the doors to the western countries. Japanese had to learn most geological concepts discovered in the western countries. A few concepts such as tsunami, Wadati-Benioff zone and Brunhes-Matuyama reversal have been given Japanese or partly Japanese names. From the late 20 Century, the International Union of Geological Sciences (IUGS) tried to brush up the new geologic time scale based on the development of plate tectonics, especially the history of earth's magnetic field. In the Quaternary Era, IUGS invited type locality of new Epoch. Japanese geologists proposed Chibanian, type locality of which is in the Boso Peninsula, near Tokyo. At the type locality, the strata thickly continued without break, because plate tectonics of Japanese Islands made rapid stratification of Quaternary sediments. It was very unique around the world. The Chibanian section includes good tuff kye layers, abundant microfossils and good evidences of the change of the Earth's magnetic field. It is currently estimated to span the time between 0.770 Ma and 0.126 Ma (770-126 ka). The beginning of the Chibanian is the Brunhes-Matuyama reversal, in which the Earth's magnetic field last underwent reversal. Chibanian ends with the onset of the Eemian interglacial period. The Chibanian name was officially ratified in January 2020. The Japanese Government has designated Chibanian section as a natural monument.