Relative dating of fossils and rocks

We discuss the 7 principles of stratigraphy first and then see how these apply to fossils.Principle of Uniformitarianism The principle of Uniformitarianism was postulated by James Hutton (1726-1797) who examined rocks in Scotland and noted that features like mudcracks, ripple marks, graded bedding, etc.Archbishop James Ussher of Armagh, Ireland, 1654, added up generations from the Old Testament and determined that Earth formed on October 23, 4004 BCE.The goal of this lecture is come to come to a scientific understanding of geologic time and the age of the Earth.radiometric dating gives the absolute age of rocks fossils etc. by using these the age of the fossils could be found.besides these two the rock strata are correlated to find out the relative age.Relative time can not determine the actual year a material was deposited or how long deposition lasted; it simply tell us which events came first.This process lead to a system of time containing eons, eras, periods, and epochs all determined by their position in the rock record.

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Principles of Stratigraphy Stratigraphy is the study of strata (sedimentary layers) in the Earth's crust.How do we know this and how do we know the ages of other events in Earth history?Prior to the late 17th century, geologic time was thought to be the same as historical time.Principle of Superposition Because of Earth's gravity, deposition of sediment will occur depositing older layers first followed by successively younger layers.Thus, in a sequence of layers that have not been overturned by a later deformational event, the oldest layer will be on the bottom and the youngest layer on top.

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