地层学是地学的核心学科。了解岩石单元的排列顺序是了解感兴趣地区地质历史的关键。地球科学家的一项共同任务是寻找某一岩石单位的地层背景资料，例如它的年龄、性质及其在地层单位层次结构中的位置。
Stratigraphy is a core discipline of the geological sciences. Understanding the order in which units of rock were emplaced is the key to understanding the geological history of an area of interest. A common task for earth scientists is the search for stratigraphic background information on a certain rock unit, e.g. its age and properties and its position within the hierarchy of stratigraphic units.
