| Geological Formations | Resistivities (Ω∙m) |
| Quaternary covering |
|
| Dry sands | 1000 to 20,000 |
| Lateritic sands and sandstones | 1000 to 100,000 |
| Sands and clayey sandstones | 100 to 1000 |
| Continental terminal (Ct) |
|
| Clayey sands and sandstones | 100 to 1500 |
| Sandy clays and sandstone clays | 20 to 500 |
| Clays | 5 to 100 |
| Brackish waters | 1 to 5 |
| Paleocene |
|
| Marls, marly clays, marl-limestones | 2 to 60 |
| Continental “hamadien” (Ch) |
|
| Clayey sands and sandstones | 100 to 5000 |
| Sandy clays and sandstone clays | 20 to 500 |
| Precambrian Base |
|
| Granite | 3000 to 60,000 |