A new field, Quantum Geophysics, is expected in the interdisciplinary field between geoscience and the physics of defects. An interdisciplinary research program of electron spin resonance (ESR) dating that detects cumulative radiation effects in natural minerals (CaCO3, SiO2 and CaSO4· H2O) and fossils has progressed considerably in these two decades. The principles and applications of ESR dating to various fields of earth sciences are described with models of defects produced by natural radiation in cave deposits, fossil shells and corals, bones, geological fault gouge (clays), volcanic ash and geothermal silica. The growth curve of defect formation in nature and in a laboratory by additive irradiation has been calculated and the age equation is given. The age can be determined directly without estimating the equivalent dose (ED).