Stratigraphic column

A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest rocks on the bottom and the youngest on top.

In areas that are more geologically complex, such as those that contain intrusive rocks, faults, and/or metamorphism, stratigraphic columns can still indicate the relative locations of these units with respect to one another. However, in these cases, the stratigraphic column must either be a structural column, in which the units are stacked with respect to how they are observed in the field to have been moved by the faults, or a time column, in which the units are stacked in the order in which they were formed.

Stratigraphy is a branch of geology that concerns the order and relative position of geologic strata and their relationship to the geologic time scale. The relative time sequencing requires the analysis of the order and position of layers of archaeological remains and the structure of a particular set of strata.

The columns can include igneous and metamorphic rocks, however, sedimentary rocks are important geologically because of Classical Laws of Geology and how they relate to the accumulation of sediments and the formation of sedimentary environments. Lithology is a study of bedrock that occurs at a specific location. The strata may contain fossils which aid in determining how old they are and geologist's understanding of sequence and timing. Geologists group together similar lithologies, and call these larger sedimentary sequence formations. There are rules on how formations are named, related to where they are located and what rock type(s) are present. All sedimentary formations shall receive distinctive designations. The most desirable names are binomial, the first part being geographic and the other lithologic. If the rock type is the same, then the formation may be called the "Lyons Sandstone," or the "Benton Shale." When there are several different lithologies within the formation, a more general terminology is used, such as the "Morrison Formation," which contains siltstone, sandstone, and limestone. “For regional studies, geologists will study the stratigraphy of as many separate areas as they can, prepare a stratigraphic column for each, and combine them in an attempt to understand the regional geologic history of the area”.^[1]