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This chain eventually ends with the formation of a stable, nonradioactive daughter nuclide.
Each step in such a chain is characterized by a distinct half-life.
For more than a hundred years the best method of arranging its history was the use of fossils or biostratigraphy.
That only worked for sedimentary rocks, and only some of those.
For example, in 1991, two hikers discovered a mummified man, preserved for centuries in the ice on an alpine mountain.