The product of the decay is called the daughter isotope. If the amount of radiation to which an object is exposed remains constant, the amount of electrons trapped in the imperfections in the crystal structure of the material will be proportional to the age of the material. The Earth's magnetic field has reversed many times during its history. Some degree of dating objects by their position in the sequence can be made with known datable elements of the archaeological record or other assumed datable contexts deduced by a regressive form of relative dating which in turn can fix events represented by contexts to some range in time. In the example, 14 C is the parent and 14 N is the daughter.
They form when living things die and are buried by sediment.
The rate of decay for many radioactive isotopes has been measured and does not change over time. Deino, A. Quaternary Dating Methods. The arrows show the typical flow pattern of the ice: Sometimes this method doesn't work, either because the layers weren't deposited horizontally to begin with, or because they have been overturned.