Sedimentary sections are subdivided by a variety of surfaces that envelope & enclose discrete geometric bodies of sediment. The partings with the greatest frequency are those in shales but bedding planes are the commonest of these surfaces to catch the geologists eye and are used by sequence stratigraphers to interpret the origin of the sedimentary section.
Brookfield (1977) was one of the first to recognize the importance of hierarchical order to the boundaries seen in sedimentary rocks. He applied this concept to the Stokes (1968) surface boundaries that occur in aeolian sediments. He classified these as: