Ordovician dating

03 Sep

In no way are they meant to imply there are no exceptions.For example, the principle of superposition is based, fundamentally, on gravity.In order for a layer of material to be deposited, something has to be beneath it to support it.Geochronologists do not claim that radiometric dating is foolproof (no scientific method is), but it does work reliably for most samples.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.

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.

A few principles were recognized and specified later.

Much of the Earth's geology consists of successional layers of different rock types, piled one on top of another.

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".

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.

They are applied by geologists in the same sense that a "null hypothesis" is in statistics -- not necessarily correct, just testable.