Las rocas sedimentarias son rocas que se forman por acumulación de sedimentos, los cuales son partículas de diversos tamaños que son transportadas por el agua, el hielo o el viento, y son sometidas a procesos físicos y químicos (diagénesis), que dan lugar a materiales consolidados. Las rocas sedimentarias pueden formarse a las orillas de los ríos, en el fondo de barrancos, valles, lagos, mares, y en las desembocaduras de los ríos. Se hallan dispuestas formando capas o estratos. Existen procesos geológicos externos que actúan sobre las rocas preexistentes, estos agentes las meteorizan, transportan y depositan en diferentes lugares dependiendo del transporte (agua, viento, hielo). De igual manera, distintos organismos animales o vegetales pueden contribuir a la formación de rocas sedimentarias (fósiles). Las rocas sedimentarias pueden existir hasta una profundidad de diez kilómetros en la corteza terrestre. Estas rocas pueden presentarse sueltas o consolidadas, es decir, que han sido unidas a otras por procesos posteriores a la sedimentación, conocidos como diagénesis. Las rocas sedimentarias cubren más del 75 % de la superficie terrestre, formando una cobertura sedimentaria que se encuentra sobre rocas ígneas y, en menor medida, en metamórficas. Sin embargo su volumen total es pequeño cuando se comparan sobre todo con las rocas ígneas, que no solo forman la mayor parte de la corteza, sino la totalidad del manto.

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Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle in place. The particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, the sediment was formed by weathering and erosion from the source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers, which are called agents of denudation. Sedimentation may also occur as minerals precipitate from water solution or shells of aquatic creatures settle out of suspension. The sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust. Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding. The study of sedimentary rocks and rock strata provides information about the subsurface that is useful for civil engineering, for example in the construction of roads, houses, tunnels, canals or other structures. Sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores. The study of the sequence of sedimentary rock strata is the main source for an understanding of the Earth's history, including palaeogeography, paleoclimatology and the history of life. The scientific discipline that studies the properties and origin of sedimentary rocks is called sedimentology. Sedimentology is part of both geology and physical geography and overlaps partly with other disciplines in the Earth sciences, such as pedology, geomorphology, geochemistry and structural geology. Sedimentary rocks have also been found on Mars.

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