<P> The law of included fragments is a method of relative dating in geology . Essentially, this law states that clasts in a rock are older than the rock itself . One example of this is a xenolith, which is a fragment of country rock that fell into passing magma as a result of stoping . Another example is a derived fossil, which is a fossil that has been eroded from an older bed and redeposited into a younger one . </P> <P> This is a restatement of Charles Lyell's original principle of inclusions and components from his 1830 to 1833 multi-volume Principles of Geology, which states that, with sedimentary rocks, if inclusions (or clasts) are found in a formation, then the inclusions must be older than the formation that contains them . For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer . A similar situation with igneous rocks occurs when xenoliths are found . These foreign bodies are picked up as magma or lava flows, and are incorporated, later to cool in the matrix . As a result, xenoliths are older than the rock which contains them . </P>

The law of included fragments states which of the following