What is the difference between relative dating and radiometric dating
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).A common form of criticism is to cite geologically complicated situations where the application of radiometric dating is very challenging.
For example, wave ripples have their pointed crests on the "up" side, and more rounded troughs on the "down" side.
They are the "initial working hypotheses" to be tested further by data.
Using these principles, it is possible to construct an interpretation of the sequence of events for any geological situation, even on other planets (e.g., a crater impact can cut into an older, pre-existing surface, or craters may overlap, revealing their relative ages).
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.
They are applied by geologists in the same sense that a "null hypothesis" is in statistics -- not necessarily correct, just testable.