Between the Permo-Carboniferous glaciation and the Quaternary glaciation, the climate had three characteristics:1. Throughout the world the average annual temperature was higher than that of today at the same latitude.2. The temperature range between high and low latitudes was smaller than that of today.3. The average annual temperature range was also smaller than that of today. Prom the Permo-Carboniferous glaciation to the Jurassic the climate throughoutthe world gradually turned warmer and the above mentioned two temperature ranges became shortened gradually; but from the Jurassic to the present day the climate turned again cooler gradually and the temperature ranges gradually enlarged, although such changes were marked by a number of fluctuations.A lot of theories of the Ice Ages have been proposed to explain these unusually marked climatic changes, but all of them are very insecurely founded. The climatic changes of the earth could be explained best by the variation in the obliquity of the earth’s ecliptic(ε).Planets of the solar system very greatly among themselves in the obliquity of ecliptic. The obliquity of the earth has probably changed greatly during its evolution. The computed values have shown that:1. When the obliquity is 10°, the corresponding average annual temperature, the temperature range between high and low latitudes and the average annual temperature range throughout the world are in agreement with the Jurassic climatic conditions. Hence an obliquity of 10° is inferred for the earth during the Jurassic.2. When the obliquity Changes from 23° to 10°, the corresponding climatic conditions would be like those existing from the Permo-Carboniferous glaciation to the Jurassic.3. When the obliquity changes from 10° to 23°, the corresponding climatic conditions would resemble those occurring from the Jurassic to the present day.In the earth’s history there were at least two types of variation in the obliquity of the earth’s ecliptic.1. The obliquity reached a maximum amplitude of 10° to 15° within an average period of 200 to 300 m.y.2. The obliquity fluctuated with a small amplitude of 2° to 3° within an average period of 410,000 years. The overlapping of the great and the small fluctuations represents the law of the variation of the obliquity in the earth’s history. It is the great fluctuation that had caused the alternation of Glaeiation and Nonglaciation. It is the small fluctuation that had caused the alternation of the Glacial period and the Interglacial period during the Quaternary glaciation. I am convinced that the variation of the earth’s obliquity has been the most important, though not the exclusive, cause of the climatic changes, i.e. the Ice Ages.
. 1979, 关于冰期成因问题的探讨. 地质科学, 14(3): 252-263.
. ON THE CAUSES OF ICE AGES[J]. Chinese Journal of Geology, 1979, 14(3): 252-263.