GEOL 21062 Lecture Notes - Lecture 20: Arthur Holmes, Phanerozoic, Absolute Dating
31 Jan 2020
School
Department
Course
Professor
Document Summary
Geological timescales provide a framework for deciphering the history of the earth. The geological time is measured in relative time and absolute time. The international stratigraphic divisions and their correlation in the global record. Only the phanerozoic can be subdivided based on stratigraphy and the global correlation of appearance or disappearance of fossils (biostratigraphy). In contrast, the precambrian (proterozoic and archean) are formally classified chronometrically (i. e. in terms of absolute radiometric dates). The absolute timescale is subdivided into eons, eras, periods, epochs and stages. Absolute dating: radiometric age data and astronomical cycles. Calibration of the stratigraphic to the linear time scale is a matter of discovery and estimation. Show figure of gradstein of arthur holmes and explain the importance of error in geological studies. Show figure 1. 5 and explain that the calibration is ongoing and changes can be quite significant. Essentially you have to learn in this class the relative time scales and we hand out a version.
