Circular reasoning of carbon dating
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).
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.
There are situations where it potentially fails -- for example, in cave deposits.
In this situation, the cave contents are younger than both the bedrock below the cave and the suspended roof above.
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.
For example, wave ripples have their pointed crests on the "up" side, and more rounded troughs on the "down" side.his document discusses the way radiometric dating and stratigraphic principles are used to establish the conventional geological time scale.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.To get to that point, there is also a historical discussion and description of non-radiometric dating methods.