| Rock or Sediment Type | Porosity | Permeability |
|---|---|---|
| Gravel | Very high | Very high |
| Coarse- to medium-grained sand | High | High |
| Fine-grained sand and silt | Moderate | Moderate to low |
| Sandstone, moderately cemented | Moderate to low | Low |
| Fractured shale or metamorphic rock | Low | Very low |
| Unfractured shale | Very low | Very low |