The
law of superposition is an axiom that forms one of the bases of the sciences of
geology,
archaeology, and other fields dealing with geological
stratigraphy. In its plainest form, it states that in undeformed stratigraphic sequences, the oldest
strata will be at the bottom of the sequence. This is important to
stratigraphic dating, which assumes that the law of superposition holds true and that an object cannot be older than the materials of which it is composed. The law was first proposed in the 17th century by the Danish scientist
Nicolas Steno.