| Code | Description | Items |
|---|---|---|
| 550 | Earth sciences | 21 |
| 551 | Geology, hydrology, meteorology | 344 |
| 552 | Petrology | 2 |
| 553 | Economic geology | 43 |
| 554 | Earth sciences of Europe | 6 |
| 555 | Earth sciences of Asia | 0 |
| 556 | Earth sciences of Africa | 0 |
| 557 | Earth sciences of North America | 0 |
| 558 | Earth sciences of South America | 0 |
| 559 | Earth sciences of other areas | 2 |