Accordingly, the collection intensities as defined by Research Libraries' Group (RLG) are listed below for each major grouping of call numbers. As with RLG, Level 1 refers to basic minimal coverage, Level 2 refers to basic and current information suitable for the layperson or basic undergraduate courses, Level 3 refers to instructional support adequate for most graduate research, Level 4 refers to advanced technical research support that is both current and historical, Level 5 refers to a comprehensive level of support where "the aim, if not the achievement, is exhaustiveness". (p. 16, Manual for the North American Inventory of Research Library Collections, Jan., 1985 edition). Please note that bibliographers in other subject areas may collect materials on these same topics at different intensity levels.
| LC Class | Subject | Collection Intensity |
| GB | Geomorphology, Water, Glaciology | 4 |
| GC | Oceanography | 3 |
| HD 9500 | Mining Production | 2 |
| QE | Geology | |
| 1 | Series - varied subjects | 3 |
| 3-23 | History, Biography | 2 |
| 25-31 | Textbooks | 2 |
| 33 | Statistics | 3 |
| 39 | Marine Geology | 3 |
| 40-61 | Computer Modeling | 3 |
| 65-70 | Arctic | 2-3 |
| 71-79 | US by region | 3 |
| 81-182 | US by state | 2 |
| Exceptions: | ||
| 125-126 Michigan | 5 | |
| 106-106 Illinois | 4 | |
| 109-110 Indiana | 4 | |
| 127-128 Minnesota | 4 | |
| 151-152 Ohio | 4 | |
| 179-180 Wisconsin | 4 | |
| 185-189 | Canada | 3 |
| 200-258 | Mexico, Central and South America | 2 |
| 260-318 | Europe, Asia | 2 |
| 320-339 | Africa | 3 |
| 340-350 | Australia, Pacific, Antarctica | 2 |
| 351-399 | Mineralogy | 3 |
| 420-499 | Petrology | 3 |
| 500-507 | Dynamic and Isotope Geology | 3 |
| 508-514 | Geochronology - Plate Tectonics | 3 |
| 515-517 | Geochemistry | 3 |
| 520-539 | Volcanoes & Geothermics | 3 |
| 540-545 | Earthquakes & Seismology | 2 |
| 565-566 | Coral Reefs | 2 |
| 571-599 | Sedimentology & Glacial Processes | 4 |
| 601-625 | Structural Geology | 4 |
| 651-699 | Stratigraphy | 4 |
| 700-999 | Paleontology | 3 |
| S 591-596 | Soil Geochemistry & Weathering | 3 |
| TD 196-898 | Groundwater/Environmental Eng. | 3 |
| TN 1-80 | Mining, Coal & Petroleum | 3 |
| TN 860-890 | Oil & Gas | 2 |
| TN 900 | Salts, Clays, etc | 2 |