Stratigraphic Column Explained

A stratigraphic column is a drawing by a geologist. The drawing depicts underground rocks or cliff wall rocks, showing their vertical sequence. This is used to interpret the relative sequence of geological past events.

It’s more like a diagram than a free hand drawing. When another geologist studies the drawing he knows what the rock formation looks like and he can understand the geology. Thus, he has the knowledge to speculate on the possibility of oil or natural gas deposits existing in said rock formation. Simplified stratigraphic columns are used to find oil deposits to drill.

Drawings of stratigrapic columns can also be used for engineering purposes. Engineers try to put the largest amount of information in the smallest space when making geologic maps. By drawing in engineering and hazardous identification concerns they can adaptthese columns to fit their needs.

The drawing of a specific area shows its major units of rock. The type of rocks the units are made of is also illustrated. It depicts this information by naming each unit and by what symbols are used to tell the rock type. The density is also shown.

This branch of geology is called stratigraphy. It’s the study of rock layers and layering. It involves two subfields: lithostratigraphy and biostratigraphy. Nicholas Steno started the theoretical basis for this subject in 1669. He wrote about fossils found in rock stratification. Later, William Smith created the first geologic map of  England. He worked on this during the 1790’s and the beginning of the 1800’s.

Lithostratigraphy studies the changes in the layering of rock types in a formation. Biostratigraphy studies the fossils in strata and relates the fossil content in different stratas from various rock formations that are far apart to each other endeavoring to correlate them in time the fossil fauna and flora compared must be of the same type.

There is another branch of stratigraphy called chronostratigraphy. This branch tries to comprehend the geologic history of rocks and regions. At first, geologic time was measured by the breaks in stratigraphic column. Scientists thought that world wide mountain building caused the breaks.

They thought that during this mountain building sedimentation did not occur, therefore the gaps formed.

They have realized that mountain building events aren’t necessarily universal. They have concluded that mountain building can occur in one continent during one interval of geologic time.

Geographic time shows the relationship between time and rocks. The normative stratigraphic column is the base of the geologic time scale.

There are four eras in a geologic time scale. Three of these eras are named for fossils found in the related strata. These eras are the Paleozoic, the Mesozoic, and the Cenozoic.

They refer to ancient life, medieval life and modern life. The oldest and fourth era normally lack diagnostic fossils, It’s called the Precambrian era.

Geologists divide these eras into periods of time. Rock deposits formed during a particular time period make up a system of rock.  

The periods are branched into epochs. Each rock system is branched into a series.