EAS201 Chapter Notes - Chapter 10: Geologic Time Scale, Erosion Surface, Exponential Decay
19 Apr 2016
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Unstable isotopes break down (decay: n p + e, lose 2(n+p) Rate is predictable: enables measurement of geological time. Time for half of the parent atoms of an isotope to decay into its daughter. Need to know: half-life or decay constant of the isotope, original amount of: Daughter isotope in the sample: final amount of parent or daughter isotope in the sample. Mineral grains must have formed at the same time as the rock. Stratigraphy: the branch of geology concerned with the order and relative position of strata and their relationship to the geological time scale. The analysis of the order and position of layers of archaeological remains. The structure of a particular set of strata. Few rocks contain materials that can be dated isotopically. For sedimentary strata: relative ages, order of strata, correlation. Principle of superposition: sedimentary strata are initially horizontal, in an undisturbed succession, higher rocks are younger. Correlation was used to develop a geological time scale.
