Difference between relative dating and radioactive dating
In either case, the inclusions had to be present before they could be included in the younger rock, therefore, the inclusions represent fragments of an older rock.
This principle is often useful for distinguishing between a lava flow and a sill.
Thus, we can deduce that the mudstone and shale are older than the rhyolite dike.
Thus, if the strata are later uplifted and then cut by a canyon, we know that the same strata would be expected to occur on both sides of the canyon.Principle of Inclusions If we find a rock fragment enclosed within another rock, we say the fragment is an inclusion.If the enclosing rock is an igneous rock, the inclusions are called xenoliths.Thus, in a sequence of layers that have not been overturned by a later deformational event, the oldest layer will be on the bottom and the youngest layer on top.This is the same principle used to determine relative age in the trash pits discussed previously.