Absolute dating techniques
It is not about the theory behind radiometric dating methods, it is about their , and it therefore assumes the reader has some familiarity with the technique already (refer to "Other Sources" for more information).
As an example of how they are used, radiometric dates from geologically simple, fossiliferous Cretaceous rocks in western North America are compared to the geological time scale.
The most common rocks observed in this form are sedimentary rocks (derived from what were formerly sediments), and extrusive igneous rocks (e.g., lavas, volcanic ash, and other formerly molten rocks extruded onto the Earth's surface).
The layers of rock are known as "strata", and the study of their succession is known as "stratigraphy".
In no way are they meant to imply there are no exceptions.
For example, the principle of superposition is based, fundamentally, on gravity.
Fundamental to stratigraphy are a set of simple principles, based on elementary geometry, empirical observation of the way these rocks are deposited today, and gravity.
Most of these principles were formally proposed by Nicolaus Steno (Niels Steensen, Danish), in 1669, although some have an even older heritage that extends as far back as the authors of the Bible.
An early summary of them is found in Charles Lyell's .It is these highly consistent and reliable samples, rather than the tricky ones, that have to be falsified for "young Earth" theories to have any scientific plausibility, not to mention the need to falsify huge amounts of evidence from other techniques.This document is partly based on a prior posting composed in reply to Ted Holden.After all, textbooks, media, and museums glibly present ages of millions of years as fact.Yet few people know how radiometric dating works or bother to ask what assumptions drive the conclusions. This figure wasn’t established by radiometric dating of the earth itself. Radiohalos shouldn’t exist, according to conventional wisdom!