Below you will find a table sourced from the book "The Age of the Earth" (Table 8.3) that provides strong evidence against a recent or young age of the Earth. You'll see that nuclides with half-lives less than 80 Ma that are not produced by natural processes cannot be found in nature. Since all of these can be produced through nucleosynthesis the reasonable explanation is that these nuclides have simply decayed over the 4.5 billion years that the Earth has existed.
| Nuclide | Half-life (years) | Found in Nature |
|---|---|---|
| 50V | 6 x 10^15 | yes |
| 144Nd | 2.4 x 10^15 | yes |
| 174Hf | 2.0 x 10^15 | yes |
| 192Pt | ~1 x 10^15 | yes |
| 115In | 6 x 10^14 | yes |
| 152Gd | 1.1 x 10^14 | yes |
| 123Te | 1.2 x 10^13 | yes |
| 190Pt | 6.9 x 10^11 | yes |
| 138La | 1.12 x 10^11 | yes |
| 147Sm | 1.06 x 10^11 | yes |
| 87Rb | 4.88 x 10^10 | yes |
| 187Re | 4.3 x 10^10 | yes |
| 176Lu | 3.5 x 10^10 | yes |
| 232Th | 1.40 x 10^10 | yes |
| 238U | 4.47 x 10^9 | yes |
| 40K | 1.25 x 10^9 | yes |
| 235U | 7.02 x 10^8 | yes |
| 244Pu | 8.2 x 10^7 | yes |
| 146Sm | 7 x 10^7 | no |
| 205Pb | 3.0 x 10^7 | no |
| 236U | 2.39 x 10^7 | yes - but continually produced by natural processes or man |
| 129I | 1.7 x 10^7 | yes - but continually produced by natural processes or man |
| 247Cm | 1.6 x 10^7 | no |
| 182Hf | 9 x 10^6 | no |
| 107Pd | ~7 x 10^6 | yes - but continually produced by natural processes or man |
| 135Cs | 3.0 x 10^6 | no |
| 97Tc | 2.6 x 10^6 | no |
| 237Np | 2.14 x 10^6 | yes - but continually produced by natural processes or man |
| 150Gd | 2.1 x 10^6 | no |
| 10Be | 1.6 x 10^6 | yes - but continually produced by natural processes or man |
| 93Zr | 1.5 x 10^6 | no |
| 98Tc | 1.5 x 10^6 | no |
| 154Dy | ~1 x 10^6 | no |
