Sedimentology

Sedimentology is the science that studies sediments—the solid particles derived from weathering and biological activity—and the processes that transport, deposit, and alter them at or near Earth's surface. The field aims to understand sedimentary rocks and the environments that produce them, ranging from rivers and beaches to deserts and deep oceans. Sediments originate by weathering and erosion, are transported by gravity, water, wind, or ice, and are deposited when energy conditions decrease. After burial, they may become lithified into sedimentary rocks through diagenesis, including compaction and cementation.

Sedimentary rocks are commonly classified by grain size and mineral composition. Clastic (siliciclastic) rocks include sandstone, siltstone, and shale; carbonate rocks include limestone and dolostone; chemical and biochemical rocks include evaporites and cherts. Depositional environments are inferred from sedimentary structures (bedding, cross-bedding, ripple marks, graded beds), fossils, and the mineralogical and textural composition of the sediments. Features such as mud cracks, ripple marks, and fossil assemblages can indicate arid, coastal, fluvial, deltaic, or deep-marine settings.

Field and laboratory methods combine stratigraphic analysis, facies interpretation, petrography, grain-size and mineralogical analyses, and geochemical or isotopic techniques. Applications include interpreting past climates and sea levels, reconstructing tectonic histories, and exploring natural resources such as hydrocarbons and groundwater, as well as assessing environmental and engineering concerns. The sedimentary record is inherently patchy and can be altered by diagenesis, which may complicate interpretation.