Principle of relative dating
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.
To get to that point, there is also a historical discussion and description of non-radiometric dating methods.However, note that because of the "principle of cross-cutting relationships", careful examination of the contact between the cave infill and the surrounding rock will reveal the true relative age relationships, as will the "principle of inclusion" if fragments of the surrounding rock are found within the infill.Cave deposits also often have distinctive structures of their own (e.g., spelothems like stalactites and stalagmites), so it is not likely that someone could mistake them for a successional sequence of rock units. Each of them is a testable hypothesis about the relationships between rock units and their characteristics.The same principle is also used in relative dating of sedimentary rocks.It must be noted, however, that this premise holds water only if the inclusions are really made of matter that is foreign to the rock that contains them. Igneous Rocks: A Classification and Glossary of Terms: Recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks, 2nd Edition.