Sedimentology

Article By:

Middleton, Gerald V. Department of Geology, McMaster University, Hamilton, Ontario, Canada.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.612350

The study of natural sediments, both lithified (sedimentary rocks) and unlithified, and of the processes by which they are formed. Branches of this discipline have been known as sedimentation or sedimentary petrology, or they have been included in stratigraphy. Sedimentology includes all those processes that give rise to sediment or modify it after deposition: weathering, which breaks up or dissolves preexisting rocks so that sediment may form from them; mechanical transportation; deposition; and diagenesis, which modifies sediment after deposition and burial within a sedimentary basin and converts it into sedimentary rock. Sediments deposited by mechanical processes (gravels, sands, muds) are known as clastic sediments, and those deposited predominantly by chemical or biological processes (limestones, dolomites, rock salt, chert) are known as chemical sediments. Figure 1 shows a diagram of the processes that are involved in the sedimentary cycle. See also: Stratigraphy; Weathering processes

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