Stratigraphy is the modern day concept of studying about the layers (strata) which were deposited with time. Depending on how the layers are deposited on the ground archaeologists study the history and civilisation of people who lived during that era. The concept of stratigraphy is based on a law called the law of superposition where it is said that the layers which were deposited at the bottom are said to be older when compared to the layers which are deposited on top, unless it was not disturbed by a natural process or if its sequence has not changed.
There are several types of stratigraphy, and we have listed out some of them for you:
Geochronology is the radiometric stratigraphy where rocks are studied and based on the rocks, the time sequence of geological events of the history of the earth is determined. Geochronology widely developed during the 20th century.
The polarity reversal study of the Earth’s magnetic study field by Rutten in the year 1959 gave birth to Magnetostratigraphy. In the year 1964, it is said that the magnetic polarity reversals were also found in marine deposits.
In the year 1979, ICS had published its first edition of the Stratigraphic Guide which was mainly released to promote the agreement of the various principles that are stated in Stratigraphy. In the year 1983, a new version of the stratigraphic code was proposed by the American commission and this expanded its scope. In the year 1987, the standard stratigraphic classification was accepted, and it was updated in the year 1994. An abridged version of the book was also published, and it was put on the website of International Commission on Stratigraphy.
By the word itself, we will be able to guess the meaning of this particular type. The term Facies Stratigraphy comes from Latin which means face or appearance. The combined paleontological and lithological characteristics were introduced in the year 1838 named Amanz Gressly. He made most of his studies on the mount Jura.
The term Chemostratigraphy or chemical stratigraphy is the study of the variations of chemicals on the sedimentary rock sequence. The field has quite young and has come into the picture only from the 1980s. Different chemical signatures can be used to calculate the age of the rocks and the deposits.
Sequence Stratigraphy is mostly related to geology where the deposits are divided into various units and scales, and they are studied. The method focuses on mapping the strata based on the surfaces which happen to have timelines like flooding surfaces. This method is kind of an alternative to the lithographic approach where the similarities of the rock units are discussed than its time significance.