Nucleon is the elementary particle consisting of material, and defining the natures of immense variety of material. To study
on nucleons is not only an immortal subject in physics, but in
geoscience and other nature sciences. Nuclear geology prompted by Professor Hou Defeng opened up new research area in geoscience in China. The major ideas of nuclear geology generally are that the nuclear conversions in the Earth make the original elements and isotopes to be converted into the new substances in accordance with the some geochemical regularity, which is main cause for the geochemical compositions update;and change in the Earth. The processes of the nuclear conversions must accompany with release of energy, which is the main energy source of the Earth
evolution that include radioactive decay energy,nuclear fission energy and nuclear reaction energy. Only those nuclides which have half-life from 106 to 1010 years can play an important role in the Earth evolution,their decay energy could reach about 5.1×1020 23×1020cal/year. Nuclear fission can release either large amount of energy or neutrons, resulting in chain reaction,for example, neutron induced fission of 235U is the most important energy source among nuclear energies. Based on the processes of radioactive decay, radiogenic fission track, and the phenomena of crystal injures caused by the natural radiation,some radiometric dating methods have been established, such as 14C dating, TL and ESR dating etc. These dating methods can provide accurate time scales for study of the Earth evolution and paleoclimatic changes, isotopic fractionation effect has also been becoming the important bases for these studies. The application of oxygen isotope of deep sea sediment provide us an useful proxy indicating the paleoclimatic changes. Cosmogenic nuclides, such as 10Be, 26Al, 36Cl, can be used to date the erosion of earth surface, glaciation and deglaciation, the formation and exposure ages of geological bodies. Isotopic tracer has been widely applied on environmental monitoring and other research fields. Nuclear geology has become the symbol that link geoscience closely with other nature sciences and modern technique.