The dominant bedrock lithologies can be selected by the "Rock Group A" item heading. The Rock Group A category contains 7 lithologic categories and a category for freshwater. Rock Group A can be further divided into more specific lithology groups, in the attribute Rock Group B. The Rock Group B category contains 18 lithologic categories and a category for freshwater. Below is an outline of all the major (A) and minor (B) rock groups.
| Rock group A value | Rock group B values |
|---|---|
| basin sedimentary | Mesozoic Basin sediments, Narragansett Basin sediments |
| calcpelite | calcpelite |
| carbonate rocks | carbonate rocks |
| granite | Avalon Granite, alkali granite, granite (other), Grenville granite, peraluminous granite, felsic volcanics |
| mafic rocks | basalt, mafic rocks, ultramafic rocks |
| metamorphic rocks | calcgranofels, pelitic rocks, sulfidic schists, metamorphic rocks (other) |
| unconsolidated sediments | unconsolidated sediments |
| water | water |
The rock group fields categorize the 37 lithochemical units into related groups with differing degrees of detail. Below is a listing of the lithochemical units in each rock group:
| Rock group A value | Lithogeochemical units |
|---|---|
| basin sedimentary: | 21c, 22u, 23u |
| calcpelite | 13u, 34c |
| carbonate rocks | 11u, 12u, 12g, 12gc, 12gs, 12s, 13u |
| granite | 61u, 61v, 62u, 62n |
| mafic rocks | 41u, 42u, 43u, 43s, 44u, 45u, 50u |
| metamorphic rocks undivided | 11u, 12u, 31u, 31c, 31gs, 31s, 32u, 32c, 2gc, 32s, 33u, 33c, 33cs, 33s, 34u, 34c, 34cs |
| unconsolidated sediments | 70u |
| water | -9999 (none) |
Rock Group B (Rock_GpB) with ID (R_GpB_ID) in parenthesis, and the lithogeochemical unit(s) (litho_code + lith_mod) contained in each category:
| Rock group B value | Lithogeochemical units |
|---|---|
| carbonate rocks (1) | 11u, 12u, 12gs, 12s |
| calcpelite (10) | 13u, 34c |
| calcgranofels (11) | 31c, 32c, 33c, 34c, 34cs |
| Mesozoic Basin sediments (20) | 21c, 22u, 23u |
| Narragansett Basin sediments (21) | 23u |
| metamorphic rocks, other (3) | 33c, 34u, 34c, 34cs, 34s |
| pelitic rocks (30) | 31u, 31c, 31gs, 32u, 32c, 32gc, 33u |
| sulfidic schists (31) | 31s, 32s, 33cs, 33s |
| mafic rocks (4) | 41u, 42u, 43u, 43s, 44u, 45u |
| basalt (41) | 41u |
| ultramafic rocks (5) | 50u |
| granite, other (6) | 61u, 62u, 62n |
| felsic volcanics (60) | 61v |
| Grenville granite (61) | 61u |
| Avalon granite (62) | 61u, 62u |
| peraluminous granite (63) | 61u |
| alkali granite (64) | 61u, 62u, 62n |
| unconsolidated sediments (70) | 70u |
| water (0) | -9999 |
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