* assume that radiometric decay rates have remained constant and are unaffected by environmental changes.<ref>This assumption is known to be false. Tests of [[radiometric dating]] methods have often shown that they do not agree with known ages of rocks that have been seen to form from volcanic eruptions in recent and historic times, and there are also examples of [[radiometric dating]] methods not agreeing with each other.</ref> | * assume that radiometric decay rates have remained constant and are unaffected by environmental changes.<ref>This assumption is known to be false. Tests of [[radiometric dating]] methods have often shown that they do not agree with known ages of rocks that have been seen to form from volcanic eruptions in recent and historic times, and there are also examples of [[radiometric dating]] methods not agreeing with each other.</ref> |