Article
Article
Stratigraphy
Article By:
Christie-Blick, Nicholas Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York.
Last reviewed:December 2019
DOI:https://doi.org/10.1036/1097-8542.659000
A discipline involving the description and interpretation of layered sediments and rocks and especially their correlation and dating. Correlation is a procedure for determining the relative age of one deposit with respect to another. The term “dating” refers to any technique employed to obtain a numerical age, for example, by making use of the decay of radioactive isotopes found in some minerals in sedimentary rocks or, more commonly, in associated igneous rocks. To a large extent, layered rocks are ones that accumulated through sedimentary processes beneath the sea, within lakes, or by the action of rivers, the wind, or glaciers; but in places such deposits contain significant amounts of volcanic material emplaced as lava flows or as ash ejected from volcanoes during explosive eruptions. See also: Dating methods; Igneous rocks; Rock age determination; Sedimentary rocks
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