ERSC 3P12 Lecture Notes - Lecture 1: William Thomson, 1St Baron Kelvin, James Ussher, Henri Becquerel
20 May 2016
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Etymology: stratum, layer, latin; graphia, to write about or document, greek. The adjective stratigraphical used as early as 1817 by william smith. Strictly, the branch of geology dealing with the study of the nature, distribution, and relations of the stratified rocks of the earth"s crust. Since all rocks are to some degree stratified, stratigraphy has come to cover all classes of rocks and sediments sedimentary, igneous, metamorphic; consolidated, unconsolidated. Lithostratigraphic (rock) units can be correlated over distance based on their lithologic similarity, and yet be diachronous. Chronostratigraphic (time-rock) units represent a specific interval of geologic time. Defined using criteria that are synchronous (ash beds, magnetostratigraphic polarity changes etc. Geochronologic (time) units intervals of geologic time represented by chronostratigraphic units. Consider an hour glass, inverted so sand flows through it in a given time (one hour). The duration of the sand flow represents an hour, but the sand itself cannot be said to be an hour.
