1．Tayama's field records by publication of papers

The book “Coral Reefs in the South Seas” was published by Tayama（1952 a, in Japanese）. It was the collected results of his scientific research on the coral reefs of the South Seas for more than ten years since 1932 as requested by the Hydro-graphic Office when he was an assistant professor at the Tohoku University. He was also a pioneer of Japanese marine geology in the early years of marine science.

This volume, contributed not only to those engaged in hydrographical business but also to the Marine Geological Society. He also wrote about the “North-West Pacific Ridge” in Bathymetric Chart No. 6901（Tayama, 1952b）. Regrettably, this paper was not referred to Dietz's paper in 1954.

Tayama's papers were almost all written in Japanese. The term “Emperor Seamounts” by Dietz to describe Tayama's North-West Pacific ridge instantly became popular around the world. It was revived by the sea-floor spreading hypothesis （Hess, 1962） and after it rapidly evolved into what is now called Plate Tectonics. Most of all, it is now well-known that the Emperor Seamounts problem has an important position in Pacific geology. If the eruption of Myojin-sho had not occurred, “Emperor Seamounts” would not have been born.

2． Backgrounds of submarine geology to seafloor spreading

The scientific study of oceanic islands began two centuries ago, but several new factors have made them more inviting objects of study. The results are as follows；

・1842：“The Structure and Distribution of Coral Reefs” by Darwin, one of the first scientists to learn the advantages of investigating oceanic islands.

・1932-1943：Tayama's scientific works research on the coral reefs and discovered the orientation and age sequence of the coral reefs of the South Seas.

・1946：“Drowned ancient islands of the Pacific basin” by Hess.

・1950s：The 1950s became a golden age of deep-sea exploration, and geologists once again addressed the questions about oceanic islands that had been raised a century before.

・1951：“Submarine geology of the Gulf of Alaska” by Menard and Dietz.

・1952：“Bathymetric Chart of the Adjacent Seas of Japan” （No. 6901）by the Hydrographic Office and “Coral Reefs in the South Seas” by Tayama.

・1953：“Foraminifera from Mid-Pacific flat-topped seamounts” by Hamilton.

・1954：“Marine geology of northwestern Pacific：Description of Japanese Bathymetric Chart 6901”by Dietz.

・1956：“Sunken islands of the Mid-Pacific mountains”by Hamilton.

・1960：“The rift in the ocean floor” by Heezen.

・1961：“Continent and ocean basin evolution by spreading of the sea floor” by Dietz.

・1962：“History of ocean basins” by Hess.

・1965-：After three years from birth of sea-floor spreading idea exchange to Plate Tectonics by J. Tuzo Wilson, and progressed to Plume Tectonics in 1990s.

The whole scientific world was aware of the remarkable age progression of the guyots and Pacific islands.

Professor Kitiro Tanaka developed the Relief Contour Method to emphasize topographic view on an orthographic map in the middle of the 20th century. The above method allows a cartographer to create contours with variation of line thickness representing brightness of ground surface caused by the incoming light from northern-westward in an altitude 45 degrees. Articles of the method include mathematical explanations for a cartographer to draw the contours producing a stereoscopic effect covering continuously over a map. The Relief Method was adopted to publish a bathymetric chart of adjacent seas of Japan in a scale of 1: 8,000,000 by Japan Hydrographic Department in 1952. The method is most suitable to describe topographic knowledge around Japan for people who have scientific interest in deep seas. Although it has not progressed to explain the mechanism of the vision of human eyes effected by the method, modified relief contour methods were coming up in the field of computer cartography since last quarter of the 20th century. If an improved visual recognition model for feeling of three-dimensionality were developed, more refined methods derive from the Tanaka's method would be applied to computer cartography.