Two invented burial clocks
A and B decay with different half-lives while production is zero. Time is in arbitrary units.
Blue: A, half-life 1. Orange: B, half-life 2. The curves show fraction of each initial inventory, while the result reports absolute inventories.
Fictional nuclides with arbitrary half-lives. No burial age for actual isotopes is calculated. Continued production, shielding, erosion, inherited histories and repeated exposure are omitted.