Sedimentary Rocks
There are three classes of sedimentary rocks.
| CLASTIC |
rocks are the deposited eroded remains of earlier rocks |
| CHEMICAL |
rocks are formed from precipitation out of solution |
| ORGANIC |
rocks are formed from the deposited remains of living material |
Not in the table
| TYPE |
SEDIMENT |
CHARACTERISTICS |
| CLASTIC |
Conglomerate |
Cemented - large, rounded |
| Brecchia |
Cemented - coarse, angular |
| Gritstone |
Coarse |
| Sandstone |
Medium |
| Greensand |
Contains glauconite |
| Greywacke |
Deep ocean sediments |
| Siltstone |
Fine - high quartz content |
| Loess |
Fine - angular particles |
| Marl |
Fine - silt or clay with limestone cement |
| Shale |
Very fine - dense clay layered with detritus |
| Mudstone |
Very fine - clay cemented with iron or calcite |
| Clay |
Very fine - absorbent |
| CHEMICAL |
Limestone |
Calcium carbonate |
| Chalk |
Calcium carbonate, soft, microfossils |
| Tufa |
Calcium carbonate - formed in fresh water |
| Dolomite |
Calcium and magnesium carbonate |
| Ironstone |
Limestone or chert - high iron content - often Pre-Cambrian |
| Chert and Flint |
Chalk or limestone containing nodules of hard silicatious material |
| ORGANIC |
Peat |
Plant material |
| Lignite |
Carbonaceous - soft |
| Coal |
Carbonaceous - hard |
| Jet |
Carbonaceous |
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