Quaternary dating methods ppt
Keyed to the relative time scale are examples of index fossils, the forms of life which existed during limited periods of geologic time and thus are used as guides to the age of the rocks in which they are preserved.William "Strata" Smith, a civil engineer and surveyor, was well acquainted with areas in southern England where "limestone and shales are layered like slices of bread and butter." His hobby of collecting and cataloging fossil shells from these rocks led to the discovery that certain layers contained fossils unlike those in other layers.See more information about "Strata" Smith and his original geologic map of England.Information about Simon Winchester's delightful biography of Smith, The Map That Changed the World is available at Tree-Ring dating is based on the principle that the growth rings on certain species of trees reflect variations in seasonal and annual rainfall.
The Major Divisions of Geologic Time are shown here, arranged in chronological order with the oldest division at the bottom, the youngest at the top. Specifically, stratigraphy refers to the application of the Law of Superposition to soil and geological strata containing archaeological materials in order to determine the relative ages of layers.Hutton, a Scottish geologist, first proposed formally the fundamental principle used to classify rocks according to their relative ages.He concluded, after studying rocks at many outcrops, that each layer represented a specific interval of geologic time.For each dating or chronological method there is a link in the box at right to take you to that section of this page.There, you will find a brief description of the method, plus links to take you to other webpages with more extensive information.