1962 Volume 35 Issue 2 Pages 67-76
The peri-glacial landform of Japan at low level, such as a few hundred meters above S. L., was built during the latest Ice Age, This landform is clearly distinguished, by its gentle slope, from the V-shaped valley of the recent development. The boundary line between these two regions is shown on the Fig. 8.
Two factors were concerned for this line, i. e., snow fall and tempereture. A part of the line, which runs from north to south, is the boundary between snow fall area to the west, and dry area to the east. The line, which runs from west to east, is determined by the gradual increase of temperature towards south.
Supposing that the pressure pattern of winter in the latest Ice Age was not substantially different from that of today, we may assume, that the snow fall pattern was almost same as today. So we can reconstruct the climatic division at that time, using climatic evidences obtained above.
The thick line on the Fig. 9 is the boundary dividing Japanese climates into two provinces, Pacific Coast type and Japan Sea Coast type. The area of Japan Sea Coast type on the Fig. 9 was a little smaller than that of today, which shows the supply of water vapour for the snow from the Sea of Japan was less than it is today.
Considering the eustatic change of sea level and other possible factors, the author concludes that the Sea of Japan was not frozen during the latest Ice-Age exept its northernmost part. The frozen area is shown on the Fig. 10.