In no way are they meant to imply there are no exceptions.For example, the principle of superposition is based, fundamentally, on gravity.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".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.
It can't float in mid-air, particularly if the material involved is sand, mud, or molten rock.A common form of criticism is to cite geologically complicated situations where the application of radiometric dating is very challenging.These are often characterised as the norm, rather than the exception.To get to that point, there is also a historical discussion and description of non-radiometric dating methods.The example used here contrasts sharply with the way conventional scientific dating methods are characterized by some critics (for example, refer to discussion in "Common Creationist Criticisms of Mainstream Dating Methods" in the Age of the Earth FAQ and Isochron Dating FAQ).Carbon-14 dating is especially popular with anthropoligists seeking to date the age of bones. Almost every biology lab will have a phosphate counter.Physicists have studied tritium decay seeking to understand fusion on the Sun.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.We have entered copper-64 (k = - 0.05331), potassium-42 (k = - 0.05776), and sodium-24 (k = - 0.03850) for 20 hours on the "Graph" menu as our default example. In 1947 the chemist Willard Frank Libby developed carbon-14 dating techniques leading to his Nobel Prize (1960). However, with few exceptions, the only radioisotopes found in the natural world are those with long half-lives ranging from millions to billions of years.