层理是沉积岩中最普遍的原生构造，包括层面以及由岩层内部的成分、粒度、结构、胶结物和颜色等特征在剖面上的突变或渐变所显现出来的一种成层性。Bedding is the most common primary structure in sedimentary rocks, including bedding surface and the stratification reflected by gradual or sudden changes of rock characteristics such as composition, particle size, structure, cement and color reflected in the profile of the strata. 沉积岩层理可根据岩石的成分、结构、色调变化去识别。The bedding of sedimentary rock can be recognized by the changes of rock composition, structure and color.