| A | B |
|---|
| Deposition | laying down of rock-forming material by water, wind, ice or gravity |
| Sedimentary rocks | rocks that form at or near the earth's surface at relatively low temperatures and pressures by mechanical and chemical processes |
| Clast | Mineral and rock fragments produced by mechanical weathering of rock |
| Chemical sedimentary rocks | Chemical sediment that precipitates from solution form rocks. |
| Thickness of sedimentary bed | Typically 1 - 100 cm |
| Clastic rocks are classified by | Grain size, grain composition, texture. |
| Shale | consits of particles less than 0.001 mm |
| Siltstone | Made of particles 0.001 - 0.1mm |
| Sandstone | Made of clast 0.1 - 2mm |
| Breccia | Made of clast > 2mm with angular edges |
| Conglomerate | made of clast >2mm with rounded edges |
| Most abundant types of sedimentary rocks | Mudrocks made of silt and clay |
| Transportation | The movement of sediments to their eventual site of deposition influences sediment in two important ways. |
| Rounding | As particle hit and scrape against each other, the edges and corners are ground away |
| Sorting | This is the process that separates grains according to size, density, and/or shape. |
| Deposition | This refers to the accumulation of sediment |
| Lithification | Also known as diagenesis is the physical, chemical or biological processes that turn sediment into sedimentary rock |
| Compaction | Involves packing together of sediment grains through burial |
| Desiccation | Involves the loss of water from sediment pore spaces. |
| Cementation | Occurs where chemicals precipitate from sediment pore fluids and bind sediment particles together |
| Most common cements | Calcite (CaCO3) and quartz (SiO2) |
| Recrystallization | Occurs when factors such as pressure, temperature and fluid phase changes surrounding the grains induces the mineral crystal structures to change and, as a result, lithify |
| Crystallization | Characterizes chemical sediments, and primarily involves formation of interlocking crystals |
| Solution | This is a process that dissolves minerals. |
| Authigensis | This is the process that forms new minerals |
| Bioturbation | This refers to physical and biological activities that occur on the sediment surface and causes it to be mixed. |
| Two main types of chemical sedimentary rocks | Inorganic and biochemical |
| Inorganic chemical sedimentary rocks | These originate from dissolved material that is precipitated inorganically. |
| Biochemical sedimentary rocks | These originate from dissolved material that is precipitated through the activities of organisms. |
| Biochemical Limestones | Limestone of biochemical origin is the result of shell forming organisms |
| Bedded chert | Forms from accumulations of microscopic marine organisms that secrete silica shells around their bodies. |
| Peat | Partially decomposed plant material that accumulates in swamps |
| Travertine | A freshwater limestone |
| Chalk | A powdery accumulation of microscopic plant and animal shells |
| Laminated bedding | Closely spaced parallel bedding. |
| Cross bedding | non-horizontal bedding caused by wind or water currents |
| Graded-bedding | Represents a progressive decrease in grain size upward through a bed, and can be used as a top of bed indicator. Grading can be caused by rapid deposition from water currents. |
| Ripple marks | Small waves on the surface of sediment caused by water or wind currents |
| Mud cracks | Polygonal cracks caused by contraction of mud as it dries |
| Geodes | Generally occur in limestone and shale, are roughly spherical hollow structures formed when a deposit of silica surrounds a pocket of water in sediment |
