Mixed Sedimentary Rock

a sedimentary rock consisting of several components differing either in particle size or chemical and mineralogical composition or origin. Mixed clastic rocks include clayey sands, sandy clays, and aleurite clays. Mixed calcareous rocks include dolomitic limestones (10–50 percent dolomite, the rest CaCO₃) and limestone dolomites (10–50 percent CaCO₃, the rest dolomite). When clastic and calcareous materials are intermixed with pure sands and limestones, intermediate mixed rocks form, such as calcareous sandstones and sandy limestones. When clayey and calcareous materials are intermixed, calcareous clays (10–30 percent CaCO₃), marls (30–70 percent CaCO₃), clayey limestones (70–90 percent CaCO₃), and other rocks form. They are intermediate between clays and pure limestones. Mixed sedimentary rocks are very common.