<P> Although the Dott classification scheme is widely used by sedimentologists, common names like greywacke, arkose, and quartz sandstone are still widely used by non-specialists and in popular literature . </P> <P> Mudrocks are sedimentary rocks composed of at least 50% silt - and clay - sized particles . These relatively fine - grained particles are commonly transported by turbulent flow in water or air, and deposited as the flow calms and the particles settle out of suspension . </P> <P> Most authors presently use the term "mudrock" to refer to all rocks composed dominantly of mud . Mudrocks can be divided into siltstones, composed dominantly of silt - sized particles; mudstones with subequal mixture of silt - and clay - sized particles; and claystones, composed mostly of clay - sized particles . Most authors use "shale" as a term for a fissile mudrock (regardless of grain size) although some older literature uses the term "shale" as a synonym for mudrock . </P> <P> Biochemical sedimentary rocks are created when organisms use materials dissolved in air or water to build their tissue . Examples include: </P>

What is the most common type of sedimentary rock