| in generating rocks | 5 | location |
| years ago | 4 | temporal |
| from plant material | 3 | other |
| crude oil → be → formed | 14 |
| crude oil → be formed → million | 4 |
| negative | neutral | positive |
| 0.289 | 0.685 | 0.026 |
| Raw frequency | 18 |
| Normalized frequency | 0.381 |
| Modifier score | 0.500 |
| Perplexity | 146.737 |