| Word |
Definition |
| anthracite |
A hard metamorphic form of coal that burns cleanly and hot. |
| bedding plane |
A nearly flat surface separating two beds of sedimentary rock. Each bedding plane marks the end of one deposit and the beginning of another having different characteristics. |
| biochemical |
A type of chemical sediment that forms when material dissolved in water is precipitated by water-dwelling organisms. |
| breccia |
A sedimentary rock composed of angular fragments that were lithified. |
| cap rock |
A necessary part of an oil trap. It is impermeable and hence keeps upwardly mobile oil and gas from escaping at the surface. |
| cementation |
One way in which sedimentary rocks are lithified. As material precipitates from water that percolates through the sediment, open spaces are filled and particles are joined into a solid mass. |
| chemical sedimentary rock |
Sedimentary rock consisting of material that was precipitated from water by either inorganic or organic means. |
| chert |
A durable sedimentary rock formed of microcrystalline quartz. |
| clastic |
A sedimentary rock texture consisting of broken fragments of preexisting rock. |
| compaction |
A type of lithification in which the weight of overlying material compresses more deeply buried sediment. It is most important in fine-grained sedimentary rocks such as shale. |
| conglomerate |
A sedimentary rock composed of rounded gravel-sized particles. |
| cross-bedding |
Structure in which relatively thin layers are inclined at an angle to the main bedding. Formed by currents of wind or water. |
| detrital sedimentary rock |
Rocks that form from the accumulation of materials that originate and are transported as solid particles derived from both mechanical and chemical weathering. |
| diagenesis |
A collective term for all the chemical, physical, and biological changes that take place after sediments are deposited and during and after lithification. |
| dolostone |
A chemical sedimentary rock formed from dolomite, a calcium-magnesium carbonate mineral. |
| evaporite |
A sedimentary rock formed of material deposited from solution by evaporation of water. |
| facies |
A portion of rock unit that possesses a distinctive set of characteristics that distinguishes it from other parts of the same unit. |
| fissility |
The property of splitting easily into thin layers along closely spaced, parallel surfaces, such as bedding planes in shale. |
| fossil fuel |
General term for any hydrocarbon that may be used as a fuel, including coal, oil, natural gas, bitumen from tar sands, and shale oil. |
| graded bed |
A sediment layer characterized by a decrease in sediment size from bottom to top. |
| limestone |
A chemical sedimentary rock composed chiefly of calcite. Limestone can form by inorganic means or from biochemical processes. |
| lithification |
The process, generally by cementation and/or compaction, of converting sediments to solid rock. |
| nonclastic |
A term for the texture of sedimentary rocks in which the minerals form a pattern of interlocking crystals. |
| oil trap |
A geologic structure that allows for significant amounts of oil and gas to accumulate. |
| organic sedimentary rock |
Sedimentary rock composed of organic carbon from the remains of plants that died and accumulated on the floor of a swamp. Coal is the primary example. |
| reservoir rock |
The porous, permeable portion of an oil trap that yields oil and gas. |
| ripple mark |
Small waves of sand that develop on the surface of a sediment layer by the action of moving water or air. |
| salt flat |
A white crust on the ground that is produced when water evaporates and leaves behind its dissolved minerals. |
| sandstone |
An abundant, durable detrital sedimentary rock primarily composed of sand-sized grains. |
| sediment |
Unconsolidated particles created by the weathering and erosion of rock, by chemical precipitation from solution in water, or from the secretions of organisms, and transported by water, wind or glaciers. |
| shale |
The most common sedimentary rock, consisting of silt- and clay-sized particles. |
| sorting |
The degree of similarity in particle size in sediment or sedimentary rock. |
| strata (beds) |
Parallel layers of sedimentary rock. |
