Note 27--Morphostratigraphic Units in Pleistocene Stratigraphy: STRATIGRAPHIC COMMISSION

A morphostratigraphic unit is a body of rock that is identified primarily from the surface form it displays; it may or may not be distinctive lithologically from contiguous units; and it may or may not transgress time throughout its extent. It may or may not represent a climatic episode that can be traced widely, as for a geologic-climate unit. Morphostratigraphic units in glaciated areas are moraines, outwash aprons, and associated forms, whereas the term also can be applied to alluvial terrace deposits, alluvial fans, lake plains, beach ridges, pediment veneers, and other such deposits. These units serve a need long apparent to those working in the bordering fields of geomorphology and stratigraphy, and furnish a formal category that permits many surficial deposits to be treated as legitimate stratigraphic entities while allowing the full use of geomorphic criteria.